After mulling it over I decided to completely re-do the funny car cage area of the chassis, including the lower crossmember in that area. This way I can make sure
the cage covers the full helmet in case they ever change that rule, and I can design it so that the seat can slide back if a taller person ever needs to drive it.
At the same time I am taking some weight out but adding strength by designing the chassis portions to function like a truss.
Next step was to remove the cage bars that passed through the rear window so I could pull the cab all the way off:
Here you can see the portions of the cage as I cut them out. I started making cuts with a Sawzall (even using genuine Milwaukie Made in USA blades), but I
completely dulled a blade in just two cuts on this 4130 tubing! It seemed to cut harder near the welds, presumably due to some hardening that took place during the
welding process. Remaining tubes are being cut either with the plasma cutter or abraisive cutoff wheel in an angle grinder.
Of course nothing is ever easy on this project, and my trusty old Black & Decker Industrial series grinder I have had since 1988 was a casualty. I went to use the
stop pin to remove the cutoff wheel to change it out, and it was so wedged on that I broke the cast aluminum head of the grinder. I did my best to salvage it,
building a custom tool to hold the shaft so I could get the cutting wheel arbor off. I machined flats into the shaft so I could remove wheels without using the
now-destroyed stop pin. Unfortunately there was also a tooth missing in the right angle drive, so it makes a little bit more noise than before! I picked up a nice
older Milwaukee grinder off of Craigslist, and moved the B&D grinder to backup duty.
After getting tired of taking hot metal sparks in the face while cutting, I picked up a clear face shield and mounted an LED headlamp to it. I also tried using
Rain-X anti-fog on it, but it tended to scratch the lens. After a little bit of internet research I ordered some C-Clear anti-fog gel, something that is made for
use with plastic shields. When I race the truck in NHRA competition in Top Sportsman, I’ll have to use the helmet’s face shield even though I am in an enclosed
vehicle, so I figured I should have some good anti-fog stuff around! This stuff is great, it stops all fogging and leaves a nice clear lens. In my cold garage the
condensation eventually wears this stuff out, but I just need a quick swipe with more of the gel to take care of it.
I spent an afternoon at a chassis builder, bending up the new cage bars.
As I looked at the remaining tubes to be added (44 of them not counting small gussets), I decided to attempt to pick the best “grouping” of the tubes when cutting
them from a mix of straight tube sections removed from the chassis, and new tubes of varying lengths (and finally from 20′ lengths while trying to get the best yield
without waste). Even though there is a large tubing supplier here in town, their prices on smaller 4130 tubes is out of line, and therefore cheaper from an online
source (AircraftSpruce.com) even with oversized UPS shipping. As I was home sick anyway, I spent a few hours sorting this out for the best yield. Just picked up a
(hopefully final) shipment from the local supplier, and also received my package of smaller diameter tubes from AircraftSpruce. Every tube has a specific cut
pattern now for optimum yield. I just used an Excel spreadsheet to do all of that.
Next step – to free up a tube used elsewhere, I started notching the new tube to fit snugly with no gaps against the adjoining tubes. I will be doing a LOT of this
in the next couple of weeks! The big chassis shops usually use a dedicated “notcher” that positions the tube precisely then cuts it with a hardened hole saw. I
went with the redneck approach and carved the contour with a chop saw, holding the tube at the appropriate angle. Kids, don’t try this at home! With practice I was
able to get pretty good at it, but I also have a few scars from doing this when building my gasser chassis many years ago!
With the old layout the main hoop did not tie directly to the outermost frame rails, so I would have needed extra tubes running there, forming a joint that is not as
strong as it could be, and with some stress concentrations.
I removed the old main hoop and the right side roof/pillar bar, leaving almost nothing of the original chassis (and even more of that in the photo will be removed by
the time this is completed). I left a lot of the floor in place so I had something to stand on when welding towards the top!
Now a quick tip – when using a tubing notcher, be damn sure that A) the tubing is well secured, and B) the hole saw shaft support is close to the saw itself, so flex
does not allow it to move significantly. Here is a shot of me violating both of those rules, trying to cut at an angle the notcher would not otherwise work on:
And this was the result:
Yup, those teeth did not survive the rocking of the hole saw!
I am on my 3rd hole saw, the 1st 2 lasted about 4 notches total. The 3rd one is still going strong after about 16 notches. I also use wax cutting lubricant instead
of cutting oil, it seems to stay in place better.
As you can see in this photo, sometimes you have to get a little redneck in supporting the workpiece while working alone.
The redneck steps also include holding the main hoop with a ratchet strap while I tack welded it into place.
Next up was notching and welding in the new roof-pillar bar on the passenger side.
The door bars were next, which run from the main hoop at shoulder level down to the pillar bars down at the floor. These were relatively simple to notch, especially
once I figured out some of the idiosyncracies of my new notching tool.
This photo was taken while mocking up with the old main hoop, so it shows another angle of the old main hoop.
You can see here where I added a bend to give me a little more space with the driver’s side door bar. I figure space between the cage and the door is wasted space,
I’d rather have that space to be more comfortable, and to allow me to leave more space for the engine and trans towards the center of the truck.
Here is the passenger door bar installed:
The X-bars in the door opening (lower rear to upper front) are divided up at the intersection with the door bars. This was a little tricky to notch, as the angles
were beyond the capabilities of the notching tool. I did them by hand with grinding tools, a time consuming and frustrating task!
Duct tape is your friend when gravity doesn’t help hold bars in place for welding!
I notched the top portions of these bars, but did not tack weld them yet since I would be climbing in and out of the cab area for all of the funny car cage
When I laid out my tubes for the funny car cage, I made the mistake of not mocking up the driver’s seat properly, and had to revise the tubes accordingly. The main
hoop angles in quite a bit towards the top, to follow the contour of the cab, and the tube that runs behind and to the left of my helmet ends up intersecting in the
bend of the main hoop instead of at the top/horizontal portion. This ended up being a major pain to notch the tube, as it had a weird angle and was also tying in to
where the pillar bar intersected. After MANY hours and a few cuss words, I finally got it notched and tack welded into place.
Since this bar effectively blocked off access to a couple of other joints, I had to finish weld those joints first. Most chassis builders will tack the whole
chassis together then work their way around slowly doing the finish welding (to avoid having the weld draw pulling the chassis out of square). Working in small
sections you can avoid heating up the joint to the point of causing this, but it is a lot more time consuming!
Working in these tight spaces required using the short end cap on the TIG torch, which in turn required breaking the electrodes off fairly short. I made it a point
to be even more careful of not contaminating my electrode, because the “shorty” electrodes are a pain to sharpen!
As I get more tubing in place, it becomes important to figure out the order that the next tubes will go in. For example, if you have two parallel tubes which will
have another tube tying them together in the perpendicular direction, with the perpendicular tube properly notched you can’t just insert it into place! If it is a
snug fit you can’t slide it in and rotate it perpendicular. I have tried to “think ahead” and not paint myself into a proverbial corner, but managed to do it on one
pair of tubes. If you look at the parallel tubes in the photo above, I needed to get a cross-tube between them!
This was also a VERY important tube, as it’s the one my harness will wrap around securing me into the car. The seat-back brace will also tie into this tube. I
decided to make this tube larger and thicker than the minimum requirements because of this. I did NOT want to have any gaps in the mating joints, so I needed to
spread the vertical tubes out and insert a properly fitted cross tube.
Building a chassis is inherently a redneck exercise, given the use of ratchet straps, duct tape and welders, and stuff is usually sitting with the wheels off and
blocked in the air!
I’m getting closer to having the necessary tubes for the SFI certification of the chassis. I really want to get it certified before I reinstall the body and start
doing the tinwork, both for the ease of inspecting it and in case I overlooked a tube!
Next up I will be adding the remaining tubes for the FC cage area, then the new bent dash bar, then a roof x-brace, then the floor with its crossmembes and x-braces.
After that about 10 small gussets go in. Even though they are just short pieces of tubing, they take every bit as long to notch and install as a longer piece!
With those parts in I can get the chassis certified.
I’ve also obtained most of the remaining components for the build, except for the engine rotating assembly. I’ll take some photos of those parts and post them in an
I know, it’s been forever since I posted an update here. The theme of this post is two steps forward, about 4 steps back, then finally getting back to where I was!
I finished up the Funny Car cage area that I was working on at the last entry, and also added the “kidney bar” that runs next to the driver.
Searching the internet for a different piece of information I came across a post from someone on the SFI update committee, saying that they are planning to change
the spec to require the dash bar to intersect the pillar bars at virtually the same location as the door X-bars. There is no limit on the distance in the
specification, but in the “top secret decoder ring” handbook they give to chassis inspectors, they mention something like a maximum gap of 3x the diameter of the
largest tube in the junction. This would have allowed me a 4.875″ gap which I was planning to take advantage of, moving my dash bar as high as possible to clear the
high pressure turbo.
I had already removed the old dash bar and welded in a replacement in this location:
My chassis would get the certification 1st time out, but once the rule changes I would need to replace that tube for the next recertification (3 years later). I’d
rather do it now and be good, so I switched to a bent dash bar to get the turbo clearance I needed:
When it was time for the ISSPRO Pacific Coast Diesel Nationals I went ahead and mounted the cab & doors, so we could have something in our booth to attract
attention. Fortunately this portion of the chassis is light enough to just slide off the jig:
I started out carrying the thing “Fred Flintsone Style”, but ended up tying it to a hand-truck with a ratchet strap.
I had previously gotten written approval for how I wanted to build some portions of the cage, trying to meet the letter of the SFI spec even where it was difficult
due to the shape of a truck versus the car chassis that the rules reflect. I didn’t like the way I had to build it to meet the rules, but at least it met the letter
of the rules (and I was adding some supplemental gussets to make me comfortable with the design). Unfortunately once they saw it in person and photos, they didn’t
like the way it laid out either. That whole issue brought my progress to a screeching halt! We went back and forth discussing alternatives, and it went all the way
up to the head of NHRA’s technical department, before we finally agreed on a design and has their written approval.
The key areas were the base of the main hoop. I planned to add some vertical gussets, but leave the required diagonal and “kidney bar” tubes continuous and make my
gussets interrupted by those tubes (since the gussets aren’t required by the spec). They came back and wanted me to do full diameter gussets that were not
interrupted (which is the best thing for strength but technically violated the spec).
I was torn about whether to completely tear that whole area out and start over, or to try to “graft” the new tubes into place as well as I could. Since one tube
(the kidney bar) was moving locations and getting shorter, I figured I would just remove it and replace it. Since the diagonals were already fully welded and in a
position that would be difficult to grind and smooth when removing the old pieces, I decided to try to leave them and cut holes for the new gussets to pass through
Here is the passenger side after using the plasma cutter to rough in the cuts. I learned after these cuts that my electrode was worn on the cutter, which kept me
from making very clean cuts.
I used a short piece of tubing to check if I had notched enough for clearance, as the tube above kept me from easily dropping the actual length tube into place.
I had to use a ratchet strap to flex the diagonal out of the way to allow dropping the new bar into place.
The driver’s side was even more difficult since the door bar is bent outward (giving me more elbow room), which puts all these parts at slight angles.
Here’s a little detail you need to do when welding on a short section of tubing – a hole to allow the air in the tube to expand into one of the longer tubes.
Without this, as you finish the last section of weld bead it may “blowout” from the air in the tube heating up. Been there, done that!
The new path for the kidney bar put it at a sharp angle with the tube it connected to, which precluded using my notcher to cut the required “fishmouth” shape, but a
large carbide burr in an electric die grinder worked wonders for quickly shaping it.
With the replacement of the kidney bar, I was FINALLY back to the stage I was at on the project back in August!
While waiting for the NHRA decision I had plenty to keep me busy, between racing my Vega and working on my daughter’s Junior Dragster.
Both of those endeavors provided success and mechanical failures! My daughter won her first event in her Jr:
I won a few events in the Vega, including a big bracket race that was complete with a big trophy and giant check. This race had some of the best bracket racers in
the NW, I felt really fortunate to come out on top!
Unfortunately some bad things came along with the good. At a bracket race up in Bremerton I had a piston break towards the top end, and blasted out the sides of the
block and oil pan. Despite having an engine diaper, the thing still locked up solid and sprayed a bunch of water and oil onto the tires. Fortunately Bremerton is
built on a backup runway, and the guardrails are waaaaay off to the side, so I had plenty of room to do a 145+ mph slalom trying to bring it to a stop.
Back at the trailer I could see this was going to be expensive, as a huge crack was apparent in the cylinder head:
It appears that the #1 piston broke, and the rod and pin then flailed around and busted up everything in their path.
I was concerned since the very next race was the Race of Champions at the ET finals (which I was fortunate enough to qualify for the 2nd year in a row). I had a
cracked cylinder wall at last year’s RoC, and the car was smoking like crazy but I was winning rounds (got down to 5 cars left). I ended up buying a complete spare
engine from a friend of a friend (ironically a few miles from the track I broke at, but of course a few days later so I had to make the trip twice). I didn’t
realize it at the time, but it appears I damaged the front pump on the transmission when the engine let loose, so the first pass at the RoC I ended up pumping all 10
quarts of ATF under the tires at the top end of the race track, and got to do another 145+ mph slalom (and miraculously kept it shiny side up and off the walls). A
bunch of friends pitched in and we rebuilt my trans in the pits, and I was able to go a bunch of rounds on the Sunday race at the ET finals. I also went a bunch of
rounds in my truck in a cash bash during the RoC (made it to the semis).
With my daughter’s Jr, we had kept the engine slowed down with a restrictor plate on the intake. The engine was capable of mid-10′s in the 1/8-mile, but as an 8 and
9 year old she was restricted to 12.90 and slower. I had picked up a couple of 8.90 engines, but learned that we needed a much better clutch to handle the
additional power (and the good ones are built to order and take several weeks during the racing season). We went to the 1st race after her 10th birthday, planning
to open up the old engine and let her run some 10′s. Unfortunately the engine had other plans, as it broke a connecting rod right after firing it up to warm it up!
The worst part was seeing the disappointment on her face when she realized we weren’t going to be racing that day.
Now that I have a much better idea of how long each task takes in the chassis build, I was able to create a project plan to help organize the remaining tasks and
estimate a completion date. It now looks like I should get this whole thing done sometime in mid-June, just in time for the ISSPRO Pacific Coast Diesel Nationals!
One thing I forgot to add to the last update: I hadn’t driven the MBRP Dirtymax in a while as I was working on this truck, but the opportunity came up to drive it
at the last 2 events of 2012. We ended up winning the World Championship in NHRDA Pro Stock!
The coolest thing is that over 40 million viewers tuned in to watch the event on Fox Sports Net! While that’s great for the sport, I have to remember that it’s
probably a small fraction of the people who watch Honey Boo Boo (and no, I never have)…
A couple more sponsorship-related items:
Would you please “Like” our ISSPRO facebook page? It will help show the bosses that sponsoring this truck is a good thing! http://www.facebook.com/IssproInc
We are happy to announce that Mahle has signed on as an Associate Sponsor, and we will be running Mahle pistons in the truck. Don’t tell them, but even without
sponsorship help I would have gotten their pistons anyway
After all that excitement it was back to the garage! As I started finish-welding some of the junctions of several tubes, I found that I had to extend the TIG
torch’s electrode so far out that I didn’t get good shielding gas coverage. I had planned to pick up a “gas lens” for the torch, which is something that focuses the
flow into a nice even column of gas. I ended up getting a specific version of the gas lens called a CK Gas Saver, which is designed to work well at reduced argon
flow rates (saving some money in the process). It was also cool that its cup for the shielding gas is a clear pyrex-type glass, giving better visibility of the arc
I tried it out and it was awesome! Unfortunately it was also breakable, and I set the torch down on the jig to grab more filler rod, and it slid off and broke! I
ordered some spare parts and got it back together. This thing would have already paid for itself in reduced gas costs, had I started using it at the start of the
project. Heck, it is worth it in reduced blood pressure from trying to make some of those long-reach welds work!!!
Next up I installed the “X” braces across the roof of the cage. The corner mounting points resulted in some weird complex angles, so the tube end fitting was
difficult and cumbersome (but then again what HASN’T been on this build???).
One item on tube fitting that is worth mentioning: when you use a notcher to cut the contour in the mating tube, the farthest forward edges end up downright sharp.
As I discovered early on, if you don’t “blunt” those edges with a grinder, you end up with a very thin section when you weld, and if the weld puddle is at the edge
of the tubing you will end up with a hole as the thin section melts away. By blunting the edges you move the weld location to where the tubing is full thickness.
I decided to go ahead and flip the chassis over and get at all the weld spots I had skipped to this point. Once I add the front of the chassis it will be a lot
harder to flip and maneuver in my little garage!
I removed a diagonal from the firewall area, as that section will be extended to give me more room for the pedals. It was nice to have my plasma cutter working well
again, having replaced a worn out electrode!
With that diagonal out of the way, I found that the section of the original floor had a twist to it, and needed a little “persuasion” to get it flat:
I added a new crossmember and alignment tabs for holding the front frame rails into the jig.
One of the things I am trying to do is come up with quicker ways of doing some of the repeated tasks in this build. One of those tasks is cutting small strips or
plates of metal, either for the jig or for brackets on the chassis. When I built my gasser chassis many years ago I borrowed a Whitney shear and punch from my
family business, which allows me to make short work of many of those tasks. I went ahead and found used versions of the same tools on ebay to use for this build.
As I started laying out the details of the floor area, I decided it was worth it to lay it out in CAD so I had a better starting point for the measurements and
angles of the tubes I was going to be cutting and notching. I was hoping to do this in a solid CAD model, but I hadn’t touched a solid/3D CAD program in MANY years!
I had been using a freeware 2D program for the last several years to do simple stuff like laying out the rear frame of my small block Vega, and designing the
parachute mount for my big block Vega. I found a decent solid modeling program with a free demo, but was still learning it and decided to just get it done in the 2D
program I was familiar with:
I discovered that the freeware version didn’t allow angular dimensioning, but the “Pro” version was only $37.50, and I’ve gotten waaay more utility out of their
package than that over the years!
As with the prior spreadsheet I had used to organize the tubes I needed, this would help me optimize the cuts so I could get the most usable tubing out of the
lengths I had. Plus it was something to do while thawing my toes on the really cold mornings of working on this chassis! The drawing would also help me figure out
which tubes had to go in a specific order, to avoid “painting myself into a corner” like I did in the funny car cage area. With the larger diameter tubes that make
up the main floor bars, the ratchet strap trick might not work!
Armed with the CAD drawing I was able to locate and sand down all of the spots on the main tubes where there would be welds (much easier while I could tip up the
chassis), then started cutting and notching the tubes for the main floor pieces.
Yes, it looks like it’s snowing or smoky in my garage from all the crap in the air from the metal prep work. After seeing that photo I decided to go back to using a
respirator when doing that type of work!
Another thing you learn quickly about TIG welding is that the tubing needs to be REALLY clean both inside and out at every joint. When I started this work I was
only cleaning as much as I used to do with MIG welding on mild steel, and the result was a weld puddle that snapped, crackled and popped like Rice Crispies on
steroids. Now I use lots of carb cleaner to degrease, then a sanding disc on an angle grinder, plus a sanding roll on a die grinder to clean up the inside, then a
final cleaning with carb cleaner. I make sure to NEVER use brake-cleaner, as some blends include chemicals that will turn into poisonous gas when exposed to heat.
I have now received written “blessing” from the NHRA on the photos of the previously disputed areas, as well as my CAD drawings of the remaining fabrication before
the chassis certification (which should happen in just over a week when the certification tech comes to our local track). It’s tough to get a lot of work done while
still spending “quality time” with my daughter (and she’s going through a “girlie girl” phase where she doesn’t want to get dirty in the garage), so I’ve been mostly
working after 9:30 pm and between 4:00 am and 6:30 am. I do my best to always keep the doors closed when doing something noisy, but my neighbors probably still hate
At my last update I had finished the roof structure of the cage, next up was the floor.
I decided to build a generous “footbox” area, allowing me to have the pedals forward of the main firewall area. I wanted to be able to use brake pedals with a very
long stroke, to allow me a lot of leverage to create very high brake pressure. This is to hold the truck while building boost before bumping into the staging beams
and engaging the transmission brake. I also needed extra width on this footbox since I planned to use two separate braking systems on the truck, both for
functionality and redundancy in case of a failure. One system will be pretty much a typical race car braking system, with one master cylinder actuating a pair of
calipers on the front wheels and one pair on the rear wheels. My secondary system will consist of a second master cylinder, with a separate pedal positioned right
next to the other one, and it will actuate a second set of rear wheel calipers, with these ones equipped with brake pads with very aggressive cold temperature
friction. I will be able to center my foot over both pedals while building boost, then just use the “regular” pedal when slowing down after a pass, and if something
fails in the main braking system I can use the secondary system to slow down. I was hoping to run a system like this, but until a few months ago the NHRA had banned
secondary braking systems (yeah, I know, it seems ridiculous to ban a backup safety item).
Since I would have my feet beyond the “protection” of the main cage, I needed an additional tube that far forward:
As I started on the various braces across the floor, I ended up with a sharper angle than could be cut with my notcher. To make things even more difficult, I
decided to offset these tubes so the tops were flush with the larger main floor tubes.
I would be duplicating the same angle 8 different times, so I knew there was a better way to do this than trial and error. I ended up hand-shaping the first one,
then making a paper template for it:
I used the template to draw the contour on the tube, then used my plasma cutter to rough cut the shape and a die grinder with a carbide burr to do the finishing.
For the spots with the mirror image of that contour I just turned the paper pattern inside out.
Another mini-challenge was a spot where I needed to notch both ends of a very short piece of tubing, and it was too short to be retained by the notcher clamp. I just
stuck a smaller tube inside it, and a short section of the same diameter tube as a spacer, and clamped the whole mess in the notcher:
As I placed the floor diagonals I was bound and determined to weld things gradually and slowly to avoid warping the chassis again (starting with all of the pieces
tacked in, then moving around and welding small sections in different areas, stopping frequently to let things cool).
I decided to spend some of that cool-down time unpacking the Fab9 rearend housing from Chris Alston’s Chassisworks. I had previously noted that they packed the
entire box full of spray foam, meaning I literally had to dig out chunks of spray foam to get the rearend out:
It was a fun but messy time for me and my daughter. We made a huge mess and filled up 3 garbage bags with the spray foam chunks!!!
One “gray” area in the spec was whether or not I needed an additional helmet bar on the side of the funny car cage (as my helmet would not fit through the opening,
but it came close). I decided to err on the side of safety and add that bar:
It was also time to start adding a bunch of little gusssets as required by the spec:
While welding these areas and “skip welding” around I found myself having to put my torch hand onto areas where I had recently welded. I have seen advertisements
for a device called a “TIG Finger” to protect that finger while dragging it along. I recognized the material as being the same as spark plug boot heat shields. My
diesel friends might be asking what a spark plug is, but it is a contraption necesssary for gasoline engines to run I had a set of those heat shields tucked into
the trailer, so I grabbed one and kept welding:
After finish welding all of those tubes I decided to mock up the engine & trans in the chassis, to figure out their positions and how much clearance I would need:
I ended up deciding to move it back 2″ more than I had in these photos, to match up with my prior calculations for front end weight percentage. It will be
interesting to see the final product and if the numbers match up with the theoretical values in my design!
As I was welding the angled floor bars together I found it hard to get decent shielding gas coverage when I had to extend the electrode well past the torch cup. I
came across an online tip that worked well here – adding aluminum foil as a gas shield to create a little “pocket” of gas. It also helped to remember that Argon is
more dense than air and will “fall” from the torch.
My progress was briefly interrupted by some necessary work on my gasser race car. I had a starter hang up near the end of last season, which chewed up a brand new
This necessitated a quick engine removal and replacement. The mid-plate flexplate shield prevents me from removing the flexplate without removing the engine. I had
a busy time as I headed home from work with the engine still hanging from the engine hoist, but managed to get to the track in time to race and even win a few
I also had to completely revamp the drivetrain of my daughter’s Jr Dragster. She turned 10 just as the tracks were shutting down for the winter. As an 8 & 9 year
old she was restricted to 12.90 1/8-mile ET, but they make a huge jump to 8.90 ETs when they turn 10. The original engine should have gone about a 10.50 with the
restrictor plate removed. We found an end of year race running Jrs and headed out of town for it. I had just fired up the Jr to warm it up, and the throttle seemed
a little bit lazy to respond. I went to rev it up a few hundred RPM and had the connecting rod blast through the block!
I had previously bought an 8.90 engine for the car, and had a decent clutch on order. As I discovered, our ancient chassis meant that none of the “off the shelf”
parts would be a simple bolt-up. I had to fabricate a lot of the mounting brackets, to achieve the proper belt tension and engine angle.
After all that I switched back to working on the race truck. I actually liked the distraction to give me a chance to mull over the 4-link mounting brackets, as this
is one of the most important sections of the chassis. I decided to use lengths of threaded rod to space the brackets out perfectly. I even sorted through an entire
box of nuts to find the ones with the closest measurements to stack together and automatically hit my desired gap in the brackets.
I clamped the whole mess together and spent a BUNCH of time making sure everything was aligned perfectly, then tack welded it and proceeded to weld it in place a
little bit at a time!
I decided to let gravity augment my welding skills while adding reinforcing plates to the 4-link brackets:
It would have been a better appearing weld if I could have done it in a single pass, but there would have been way too much weld draw, leaving the brackets crooked
in the chassis.
One of the SFI rules requires that you have an official “builder” identification plate on the chassis. I was able to bring it to work and have it done on a CNC
At that point in time there was a National Open event where the whole NHRA tech crew would be in attendance, so I headed up there to race my Vega and to get this
chassis (hopefully) certified. The cert tech spent a while looking over the prior correspondence between me and the division tech director, then looked over my
chassis. We had the whole big issue of trying to meet the letter of the specification but accommodate a stronger design for my main hoop tying into my main
crossmember. The tech looked it over and asked why I didn’t just put a bend in each end of the main crossmember and move the junction point to where I needed it.
Crap!!! Why didn’t I think of that!!! That change would have saved me a bunch of time and headaches, but it is water under the bridge at this point! After MANY
hours and hassles I finally got my chassis certification!
After realizing how often I was refilling the 83 CF argon bottles while welding all this stuff, I traded up to a 150 CF bottle (which barely costs more than the 83′s
I kept my second bottle as the smaller 83 CF one, I only use it to finish up if I run dry on the big bottle, and I’ll keep it in the trailer when we head to out of
As I started working on the remaining design aspects of the chassis (strut mounts, rear frame including shock, anti-roll-bar and parachute mounts), the need for a 3D
CAD model seemed more critical then ever. After being disappointed with lower cost commercial packages I came across the latest version of Freecad, an open source
software package (and FREE!). I tried the then-current version when I started this project, but it had way too many unfinished features. This one really impressed
me. It still has a few glitches but works really well otherwise. Here is my model (with some items represented in rough form, like the strut top mounts are just as
cylinders, and the engine only shows the balancer and mid-mount plate). I also left out sections that are already done and don’t really need any more design work
(top of cage, floor diagonals).
I suppose things were seeming like they were going too well, so something had to happen!
We headed up to Canda for the BD Diesel event at Mission Raceway. It was a chance for my daughter to get in two separate races in her Jr, and it was also a big
bracket race that I would run my Vega in (as well as my dually in Sportsman ET). I was excited for Caitlyn as we finally had all the issues ironed out in her car,
it was running VERY consistently and she was cutting killer lights. One issue she has with unfamiliar tracks is seeing where the 1/8-mile finish line is. At our
home track they only run 1/8 mile for the weekly bracket program, so that finish line is well marked with a big white stripe, and no more cones past the finish line.
At other tracks you are lucky if there is any stripe at all, and there are cones at the 1000′, 1254′ and 1320′ marks. To compound matters they expect the Jrs at
this track to make a U-turn on the track in order to make the return road. I took her down to the return road area before we ran, and she said she had a good look
at it. On her 1st time run we derailed the chain (the tensioner had vibrated loose on the long tow there). On the next pass she cut a good light and make a perfect
pass, but stayed in the throttle way past the finish line, then tried to turn into the “switchback” return road entrance before deciding to try to go back onto the
track (which is what I always told her to do if she misses the turnoff). She ended up hitting the wall at a 45° angle, smashed up the car pretty well and gave
herself a mild concussion and severe leg bruise.
The left front wheel was mangled and torn from the chassis (hanging on by the now-bent steering linkage), the rear axle broke on the impact sending the left rear
tire hundreds of feet away in the motocross track, and the cage got flattened from the impact. The front section of the chassis is also pretty bent.
A good friend of mine (Dan Soran) builds race cars and has done a complete Jr for his sons to race, as well as a bunch of updates on area Jrs. He had previously
suggested that we borrow their car and run it, as it is a nice state-of-the-art chassis (and ours is quite outdated), and it would be a chance for exposure for him
to sell it. I decided to take him up on that, and also spent a few hours bending up tubes for rebuilding our car, as well as some tubes for the brake assembly for
the race truck. I was originally planning to take my dually, but since it is a 800+ mile round trip I decided to see if I could successfully tow with my TDI Jetta.
It towed great once I took the slop out of the hitch receiver. Nothing like getting 38+ mpg while towing!
As we get closer to the annual ISSPRO Pacific Coast Diesel Nationals (June 29th in Woodburn, OR), it is painfully obvious I won’t have my truck running for it. I
will have it on display though, hopefully rolling on its own rather than on a hand-truck like last year! Please come out and join us for this event. It will be
quite an event, with the $6500 purse for Super-Street, plus the sled pulls, and a big “Top Comp” fast gasser race to fill in the time between the diesel passes. Of
course the complimentary ISSPRO BBQ will be back as well. Hope to see you there!
First off I would like to thank everyone who came out to the ISSPRO Pacific Coast Diesel Nationals! Despite sweltering heat we had an awesome turnout of fans and
racers, and got to see some awesome racing and sled pulling. We fed the most people yet at our BBQ (despite this being the 1st year of not running gassers at the
same time). They did have a gasser “Top Comp” shootout with a limited field, just to serve as filler between the diesel classes. I hoped the big purse would bring
even more Super-Street trucks out of the woodwork, but I know a few teams had problems and couldn’t make the race, while others broke at the event before
eliminations! I was forunate enough to come out with a runner-up again in Sportsman ET, regaining the lead in National points by a single round! I was also foolish
enough to tackle singing the National Anthem for the event, doing it acapella and with almost no sleep!
Between that event and other recent events, I have been pleasantly surprised by how many people (many of them not directly involved in the diesel performance
industry) approached me to say they are following this build (and a few of you gave me some well-deserved grief for the length of time since my last update)!
Back to the race truck!
Next step was to build the lower control arm mounts. These were at strange angles in 3D space, and despite creating them in my 3D CAD model I decided to hand-fit
them to minimze gaps. I carefully built jig “extensions” which positioned tubes in the same location as the strut control arms will be.
After that I made cardboard mockups of the brackets to test-fit the shapes on the tubing. You know those annoying subscription cards that come falling out of your
new Diesel Power magazine as soon as you open it? I finally figured out a use for them in this step!
After the first piece I actually switched over to used gift cards as my test mockup models for the brackets, as they were a little less flimsy than the subscription
cards. Once I had the shape nailed down I traced it onto a piece of 3/16″ thick 4130 plate (previously sheared into appropriate width strips on my dad’s big
ironworker press), then rough cut the shape using my plasma cutter. After drilling the holes and finish shaping with a carbide burr or grinding wheel, I had my
I carefully tack-welded these in, then skip-welded (short beads in alternating locations) while still anchored in the jig.
Next up it became evident that I really needed to get some better paint on this thing for the upcoming ISSPRO event. I started going over the cab and checking out
various imperfections and cracks. I was surprised to find many voids in the original fiberglass surface, where they left a large air pocket when laying it into the
A few of those were significant and also showed up as cracks, needing some repair work. I used an old trick of laying a sheet of plastic (like from a heavy plastic
bag) over the repair to smooth it out while it cured. This helped me force the resin into the recesses from the voids in the surface.
I also found cracks in a really cheezy patch job, where they had filled in from prior roll cage rear bars.
I patched these and filled in with resin and mat, knowing that my rear bars will be at a different width anyway.
The driver’s A-pillar on the cab turned out to be really bad, with huge voids in it that turned into a complete break.
I had to use a piece of flat stock to reinforce that area, and fully glassed-in the piece as part of the repair.
Next up was shortening the bed from 7′ to 6′, to match my shorter wheelbase, After trying a couple of methods, the cleanest cut was with a cutoff wheel in an angle
I also had to remove all traces of old stickers from the panels, this was quite a chore requiring a heat gun, scraping, a couple of chemicals, and maybe a cuss word
At this point I hauled the whole mess over to the ISSPRO factory and set up shop outside the paint booth. We have a professional-quality paint booth for spraying
industrial coatings, so it was nice to not have to do this in my garage!
I shot several coats of primer and sanded between coats.
After the primer and finish sanding I was ready to shoot some color and clear.
I assembled things (including getting the grille in upside down for this photo) and hauled them out to the track for display at our race. As of 1:00 Saturday
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You really have to get these notches perfect to get good welds with minimal filler.
Then sometimes it is difficult to hold the bar in place while you double check everything:
I finally welded in the first new bar! So far it had been all about cutting other bars out and bending the new ones, so this was a milestone in the build.
Unfortunately I chose this time to try to teach my daughter about TIG welding, and discovered that when combined with too much amperage and too large of a TIG
electrode, if you turn your head for a moment it’s possible to blow a pretty big hole in the tube!
I got to patch that hole next…
I needed to add that bar so I could remove the original bar just below it, then cleaning up and reusing that bar in another location in the chassis.
My next “milestone” is to finish enough of the cage to get the SFI 25.2 chassis certification. I have always been spoiled with the region’s certification technician
only about 10 miles away, but he had to retire due to medical reasons. On March 25 a tech is coming in from out of town to do multiple certifications at the local
track, so I will have some late nights for the next several days trying to make that!
I forgot to add to the last update, I was fortunate enough to get some professional coverage courtesy of an article on Dragzine.com:
Now for more updates:
As I started this build I had been using a cheapo Harbor Freight auto-darkening welding helmet. After getting “flashed” with non-darkened light several times I
decided to find a better helmet. I picked up a nice Speedglas unit off of ebay. As usual, nothing works as planned. Ebay had some sort of error that was telling
the seller that I hadn’t paid, even though I paid immediately via Paypal. After weeks of dealing with this I finally got the dang helmet. It worked much better,
but still would give me an occasional flash when rollcage tubes blocked the sensors.
I found a really nice Snap-On helmet on Craigslist with 4 sensors, so far it has worked the best.
I liked the Speedglas one the best for comfort and breathability (it has a neat vent system), but as long as I am climbing around rollcage bars that block one or
more sensors then I’ll use the Snap-On. With a bunch of welding in awkward positions I have not been flashed yet with that one!
I took the tube I removed from the chassis previously (it was the dash bar), and proceeded to clean up the welds on it, weld a few holes shut, then notched it for
its new location. Like the last tube, this goes in a spot with a compound set of angles into a bend of another tube (where the cross section of the mating tube is no
longer a perfect circle). As a result even a notcher would not have worked, so I just did a trial and error process of grinding and fitting!
Welding this one in was a little easier since I wasn’t trying to teach my daughter at the same time!
After that I was able to start removing the whole rear portion of the chassis, one tube at a time.
I needed my steering wheel for mocking up the driver position, which ended up being a separate distraction. One of my minor hassles was trying to use a 6-hole
steering wheel with a 5-hole SFI-certified quick release. I could not find a wheel I liked in 5-hole, but found the perfect one in 6-hole.
Fortunately Grant makes and adapter ring, but like most things on a race truck it needed to be modified in order to work. They assumed you would have nuts sticking
up on the “face” of the wheel when using a 6-hole wheel on a 5-hole mount.
I prefer to have rounded button-head capscrews from the “face” side, so I drilled, tapped, and added threaded inserts to allow this.
As I plan out the remaining parts of the chassis (front and rear suspensions), I needed to finish unpacking the many boxes of parts from Chris Alston’s Chassisworks.
The components are all packed ludicrously well, including boxes that are taped up like crazy AFTER adding dozens of box staples to the flaps. I swear I have spent
more time opening boxes than welding at this point!
Here is the aluminum double-adjustable front strut body:
Aluminum front hubs
Wilwood 4-piston forged aluminum calipers
Slotted brake rotors
I took advantage of the Summit Racing 15% discount sale for New Years, and picked up a bunch of “smaller” items:
Front wheels (Weld Pro Star 15 x 3.5)
Front tires (Moroso DS-2, 26 x 4.5 x 15)
Onboard fire suppression system (Safecraft 5 lb Halon system) – my friend Shawn Ellerton should probably get one of these!
Electric shift solenoid (Shiftnoid)
I like the idea of shifting myself, but it may be too much to deal with during a pass.
Combination mid-plate and flexplate SFI shield from TCI. I actually sent this one back, as it had an SFI tag date of Oct 2011. I have heard (and seen the evidence)
that SFI allows at least 2 month “post dating” of tags from the manufacturer, so this one has been sitting around a while. As it will need replacing or recertifying
based on its manufacture date, I wanted a newer date on mine. I don’t care so much if it’s December or February, as long as it falls in the “off season” for
recertification, but the new one (which arrived in February) has an April 2012 manufacturing date on it!
Delay box (Biondo Elite 500), which will be used to control the transmission shifting and lockup.
Airaid Air Filter (specifically picked this since they are an NHRDA contingency sponsor):
And how about a little Strange? No, not the kind Charlie Sheen is always talking about, I mean Strange Engineering, who made the full floater axle kit.
Then again Charlie would like hearing about Strange times 4, and I’ve got four of these beauties going on the rear axle:
I’m going to plumb both pairs of calipers separately, and rig up a solenoid valve to allow blocking flow to one of the sets. That way I can run agressive pads on
one pair to help with spooling, but won’t have to worry about premature lockup when stopping after a run. At least that’s how it will work in theory!
Here are the hub/rotor assemblies:
Here is one of the “spindles” before it was shipped off to Chassisworks to be welded in to the Fab9 rearend they are building for me. Hoping to see that in the next
week or so!
Funny thing about the floater, it’s undeniable that a floater is the safest type of rear axle for a drag vehicle. They were required by NHRA for anything capable of
210 mph or higher, and I had it on some inside info that the rule was being “looked at” for revision. We figured that any revision would make the rule more strict,
like lowering the limit to 200 or even 180 mph, so I ordered my parts to build a floater for this truck. Then the rule change came out and they raised the limit to
240 mph! Oh well, at least I know my rear tires aren’t going to come off even with a broken axle!
After several weeks of delays, my other LB7 crank showed up (the seller had a few things come up). He wrapped it in layers of cardboard and bubble wrap:
Despite that packaging, Fedex managed to still mangle the tone ring, but as I understand it I’ll be using the one from the LBZ anyway.
The crank itself was in beautiful condition, the journals are smooth as glass.
With all this shopping, I thought my gasser might get jealous. There was a sale on Valvoline VR1 racing oil at all the Autozone stores, so I cleared out every store
on my way home one night.
This is in addition to one more case that went into the trailer! With a change to E85 in the gasser I want to keep an eye on the oil and probably change it more
With the aforementioned March 25 chassis inspection event coming up, I really started busting my butt on the chassis fab area, working on it every night and early
morning. In my recent Summit orders they have included either a Summit hat or a sample bottle of 5-hour Energy. Can you guess which one was used with this build?
I removed the rest of the original Funny Car cage:
Then I removed the rear frame section completely
Also removed the original “#1″ bar, the main rear crossmember that positions the rear suspension (arguably the most important bar in the chassis):
This needed to be replaced since it needed to be one solid piece without any splices, but had a splice in it. I checked and found that the original bar was VERY
crooked in the chassis. This thing would have launched crooked and dog-tracked after the launch!
I welded on “doublers” for the new 4-link brackets, something Chassisworks recommends for blown Pro Mod type chassis.
I squared the chassis up in the jig and welded in a new #1 bar, along with a passenger-side door sill bar (original was undersized).
At that point I noticed yet ANOTHER original weld that did not go all the way around a tube.
I cut out the original door bars
Of these, the main (from shoulder to foot) one on the passenger side was too small, and the driver’s side one needed a bend to give me some elbow room. The X-brace
parts were way too small, and did not properly connect to the main bars (they overlapped with a tiny weld between, rather than notching and fully welding).
I started notching the new main door bars to prepare them for welding:
At this point it looked like I might almost get all the bars done in time for the certification. However, I decided to wire brush off the paint in all of the areas
where I would be doing some welding. That was when things came to a screeching halt, as I wire-brushed through a layer of bondo under the paint. After removing the
paint this is what I found:
In two different critical spots someone had done an unreinforced butt weld, then went to great lengths to conceal it with grinding, bondo and paint.
As if there weren’t already so many things wrong with this chassis, but this is downright criminal to put something together like this then go to great lengths to
conceal it. The main hoop would not have been legal to splice at all in this area, but the pillar bar would have been okay with a properly inserted splice. The way
it was done it would have been very unsafe in a wreck. It looks like the original builder just didn’t have any long enough pieces of tubing left, so he just spliced
and bondoed away. I swear if I ever meet the guy who built this chassis originally, there will be a few harsh words! I still can’t believe a human being would let
something out of his shop like that, knowing that someone is expecting it to protect them in the event of an accident. I feel the same way about the safety
equipment manufacturer who approved a change to standard (flammable) thread in fire suits to save money, and more than one racer was badly burned as a consequence.
Do these people have no conscience???
Fortunately I had not welded in any of the newest tubes, so the biggest loss in time was prepping these bars after removing the original attaching bars. I ordered
more lengths of tubing, and will be bending up a new pillar bar and main hoop (with better routing to be both stronger and lighter).
NOTE: Due to the limitations on the number of photos I can post on many forums, I will post a more detailed version with more photos on the
[URL="http://www.isspro.com/blog"]newly updated ISSPRO Website:[/URL]
Please check it out over there!
Sorry for the lull in updates. Usually the gatherings of my extended family occur at my dad’s house, but he was on a 3-month cruise with my aunt and uncle, so it
fell to me to host those kind of gatherings. I hadn’t done much housekeeping since hurting my back in December, as any “spare” time was spent on the race truck. I
had LOTS of housecleaning to do before the Easter gathering. After that I went into prep mode for a child custody hearing. My attorney lets me do most of the prep
work for trial so it costs me less money, but it means a significant amount of time. Immediately after that was our family Mother’s Day gathering. Somewhere in
there I de-winterized my gasser race car and my daughter’s Jr Dragster, as we finally got in a local race without raining out.
We traveled down to Redding, CA for the Jefferson State Diesel Nationals, where I went to the 3rd round in my dually, and lost with a decent light while running on
my dial-in, as the other guy had an even better light and ran on HIS dial-in!
Two weeks later we headed to Mission, BC for the BD Diesel Nationals. That race was a little less successful, as I red-lit by 0.008, and managed to do it to someone
who forgot to put his truck in 4×4 and cut a 0.476 light and ran 2+ seconds off his dial-in. It was a little less painful to lose the good race in Redding!
In my Vega I have been sorting out some issues, after doing some datalogging I figured out that one source of inconsistency was my torque converter.
After replacing it with a custom built unit from Hughes Performance, I won two races in a row, then took 2nd in the consolation bracket the next week (went out first
round of the regular class when the other guy had a 0.008 light and ran 0.010 off his dial, while I cut a horrible light partially due to sun glare). Note to self -
when everyone is lining up in the right lane, walk around the corner and see if the sun is glaring in the eyes of the left lane racers!
I updated the rendering of the truck to represent the altered wheelbase. I wanted to see how goofy it looks. I’m a bit biased but I kinda like it!
Despite the aforementioned items taking up my time, I still managed to keep working steadily (if not slowly) on the race truck. As we last left off I was basically
starting the chassis over. With the help of my friend Duane Merritt and his chassis shop, we bent up some new bars. It was nice to start from scratch and make a
few changes in the design of the chassis. A key part was the way the main hoop ties into the floor area and main crossmember. With this change I could get less
likelihood of the main hoop collapsing, without resorting to gussets which can cause a stress concentration.
Just to help understand some of the decisions I have made on this chassis, here is a quick Structural Engineering 101:
When it comes to structural strength, bigger is NOT always better. In many cases you can make a part STRONGER (able to carry more load without failure) by REMOVING
material. As counter-intuitive as this sounds, let me see if I can explain in a way that makes sense.
Metal fails when the load causes a stress level beyond its limit at that specific location. If a bar is undergoing a bending load, that bar will deflect
proportinally to the load. However, if one section of that bar is “reinforced” such that it has much less deflection, the section adjacent to it will have
substantially MORE localized deflection than without that reinforcement, as it is now the weak point with higher stress. This extra deflection is effectively a
“stress riser”, or a spot with increased stress, and a likely point of failure. If you remove some of that reinforcement such that the whole bar “distributes” the
deflection evenly, the peak stress level will decrease. Basically you want to avoid drastic changes in cross section.
To save you from going back a few pages, this is what the main hoop used to look like:
orning I had been running on about 4 hours of sleep since Tuesday morning!
Of course I put a ton of scratches in my fancy new paint hauling it back and forth from the track, but at least it is starting out looking reasonably nice (compared
to my Vega that still has the same primer and damage from 1988)!
Sorry for the lack of posts in recent months. I am absolutely humbled at the number of you who have asked me (via emails, PMs, phone calls & in person) for updates
on the truck build. Unfortunately the rate of progress had slowed significantly, as some family matters had to be given higher priority. Following the last update
I had to devote significant time & resources to a child custody hearing (which dragged out into multiple dates). After that the main tasks were finding a new school
for my daughter & lots of attention helping her get settled in (she is now with me 85% of the time).
Another distraction was preparing for the annual SEMA show in November, where we debuted our new datalogger (with built in 3-axis accelerometer and RPM & vehicle
speed sensor inputs).
We also debuted the EV2 output module (which allows EV2 gauges to control external devices based on the value of whatever the gauge is measuring). I plan to put
both of these products to good use in the race truck, using the datalogger of course to monitor all of the passes, and the output module to control things like
cooling fans and potentially water/methanol injection.
While at the show I met up with an old friend (Steve Darnell) who is about to star in his own reality show building rat rods (coming in April on Discovery).
Coincidentally I met a guy who is also starting a reality show building rat rods, Aaron Hagar. Yes, of THAT Hagar family (he is Sammy’s oldest son). His show will
be coming soon on the History Channel.
Getting back to the race truck: Continuing on the front suspension. Part of my plan to achieve desired front/rear weight distribution is to stretch the front
suspension out as far as I reasonably can. This is a concept that doesn’t really make sense intuitively unless you really think about it, but with a given
relationship between the main masses (engine/trans) and the rear tires, the farther forward you can put the front wheels, the more static load goes on the rear
tires. I will eventually stretch the fiberglass nose to improve the appearance, but mocked things up to make sure they physically fit now (even if it looks a bit
I researched the ways various chassis builders position the front strut upper mounts for welding. Some have fixtures for positioning the top strut cup, while others
focused on the wheel hub position, then set the strut at the correct alignment and position the mounting brackets around that. In the prior post I had already
positioned the lower control arm mounts, so I figured it would be a good “base” to use with the wheel hub positioning method. As a bonus I could reuse the wheel hub
fixtures to position the rearend once I get to that step.
I drew up the bolt pattern on CAD, then used that to mark up a couple of pieces of steel. For the big hole with the hub I stole my daughter’s compass to draw it,
then marked over the pencil with a paint pen so I could see it while cutting.
I used a plasma cutter to rough cut the circles, and eventually cleaned up the cut with a die grinder.
I clamped, measured, nudged, remeasured, etc. several times to get the hub mounting plates in precisely the right position on the Jig.
I welded it in place, and was very proud of myself when confirming that it had not moved from the proper location.
Then I thought about it and realized that I needed to be able to move the hub up and down in order to check for bump steer! I punched a couple of holes in the plate
and mount (using my Whitney punch I mentioned in a prior post), then enlarged the holes to be a near-interference fit with the bolts. After cutting the welds I was
able to get it bolted back into the proper location.
Now it was time to assemble the strut top mounts. They come as flat plates which must be notched to match the tube contour, then welded to some machined cups which
hold the sperical top strut bearings.
I made the mistake of trying to tack weld the 1st one with just gravity holding it.
As it cooled of course the weld draw caused the other side to pop up! I tried clamping it down (using a piece of scrap aluminum to try to let it clamp tight despite
the lip on the edge).
I forgot to take a picture of it, but this was a disaster as the metal tore at the thin section while it was heated for welding. I needed something to clamp it
together while leaving me room to tack weld. A quick glance through my rollaway found a front hub wrench which worked perfectly, allowing me to force the wayward
bent/torn piece into shape for final welding.
I proceeded to “skip” weld around the perimeter on both sides, being careful not to overheat the thin edges. With the skip welding the beads don’t look as nice as
they would otherwise (you can see where I stopped to move to another area), but it is necessary to prevent warping!
Next up is the assembly of the struts themselves.
Starting with a pile of parts, the strut bases need to be pressed on with dowel pins, then the steering arm is secured with a stud which passes all the way into the
strut body. There are also two 3/8″ bolts which thread into the base and prevent the steering arm from turning (and also give it some support from bending). As I
followed the instructions of adding Loc-Tite and torquing both the stud and the bolts, I ran into a couple of issues.
First up, the stud was too deep to use even my deepest sockets to reach the 7/8″ hex. Fortunately I had a 7/8″ crowfoot flare nut wrench which I bought for changing
the fuel bowl heater on my Powerstroke! When torquing with a crowfoot, remember to take the extra leverage into consideration. For example, if the crowfoot moves
your pivot point 2.0″, you multiply the required torque by 12/(12+2). As I went to torque the smaller bolts I discovered they had 5/16″ 12-point heads, which isn’t
one of the options in most socket sets! Fortunately my Powerstroke specialty tools saved the day again, as I had purchased one (and had it stashed with my “special”
sockets) to use on the 8mm 12-point bolts holding the downpipe to the turbo. I did discover that the bolts were too long for the holes, and they actually bottomed
out about 0.080″ before becoming tight. Be sure to check little details like that when building a race car/truck, at a glance it might have gone unnoticed! I was
going to add washers, but decided to make lemonade out of the lemons, I will space them up with a separate bracket I will add later to anchor a front suspension
travel limiter. I was trying to decide where to mount such a bracket anyway, so this made the perfect solution!
The Chassisworks strut kit includes a 4130 Chrome Moly strut bottom piece, which holds a spherical bearing for the bottom of the strut, and the rear control arm bar
welds to it (so it effectively becomes part of the lower control arm). I had to temporarily press the spherical bearing into place for fit-up, but it will be
removed later for the welding on that part. The installation instructions warn you more than once: DO NOT EVEN THINK ABOUT WELDING WITH THE SPHERICAL BEARING IN
PLACE! (or words to that effect)…
I installed the hub for that side, since that is what is going to mount to my jig holders for positioning the strut assemblies.
The other ends of the control arms are threaded ends with spherical rod ends. I installed the ends at the midpoint of their usable adjustment, then measured the
lengths of the tubes for the lower control arms.
This was easier said than done, as the whole mess moves around in 3 dimensions but the strut top, hub center and angle needs to be precisely positioned. I ended up
just placing the overlength tubes in place and measuring the distances from the mounting holes
After cutting the tubes to length I mocked it all into place, adjusting over and over until I had everything positioned and angled correctly. I was nervous cutting
the control arm tubes until I realized they were just 1″ x 0.058″ tubing (I had a bunch of it for other parts of the chassis in case I screwed up).
At this point I realized that the front strut support bars would be passing very close to the front control arm mount (which was just tack welded into place at this
point). As I confirmed that its position and ange were perfect in positioning the strut assembly, I finish welded it and added a gusset.
I made sure to set the strut angle at 10° backwards, setting it up for a positive caster alignment.
The next detail was to hold the strut at the exact “at rest” position that I wanted. This is one of those situations where building a truck rather than a car, and
picking some unusual components can lead to some variations from the “generic” component instructions. I went with the longer (4″) stroke struts, and the overall
geometry was a bit different being a truck. The instructions that came with the struts would have had me installing them about 3″ above the fully compressed
position, which would have been more appropriate for an off road racer than a drag truck! A phone discussion with the manufacturer confirmed that I should be at 1″
to 1.5″ above fully compressed. I went with 1.375″ above the fully compressed position, and cut some sections of fence post tubing to the exact length to hold the
struts at that height. I cut a slot in each piece so they could be easily slid in and out of the assembled strut.
I did not have the luxury of readily replacing a screwed up cut when it came to the main strut support tubes, which have a bend (which I already did at my friend’s
chassis shop) and are quite long. If I screwed these tubes up I would be buying another 20′ length of tubing, then running to my friend’s shop to bend another one
(a big wasted of time & money). As a result I roughed the cuts and notches in initially too long, then worked it down to the correct dimensions. In other words,
measure 10 times, cut 5 times…
With weld draw as a possible issue, I did several VERY small tack welds to help hold things in place (and went back and checked position several times), then
proceeded to stitch weld the ends of the tubes to the chassis. Since my electric heaters could only bring my garage up to about 39°, I made sure to preheat the weld
areas with a heat gun.
The upper strut cup mount could only be lightly tack welded while having the upper spherical bearing in and attached to the strut (to prevent strut and bearing
damage). I measured the angle of the mounting plate to make sure it remained unchanged as I disassembled and welded on it.
After removing the strut I used some sockets and a C-clamp to press the spherical bearing out of the mount.
Of course no matter how careful I was with the C-clamp, I managed to tweak the angle of the mounting plate, but at least it was easy to bend it back to the original
I tacked in one side gusset to the mounting plate to help hold it while I stitch welded the plate into place.
I then proceeded to stitch weld the strut top mount, as well as both ends of the strut bars, then added the 2nd side gusset to the strut mounting plate. I mentioned
previously about drilling air holes to relieve pressure when welding on shorter sections of tubing. I figured this section of tubing was long enough to not need it,
but since I was alternating my welds on both ends AND the center, it still got hot enough to blow out while I was laying a bead!
Aside from that I was able to get things anchored down pretty well, and everything was positioned exactly where it was supposed to be. I wanted to make sure to have
the chassis as stable as I could, due to my next plans… Hmm, what could those be?
After that thrilling cliffhanger I’m sure you were all wondering what was next? Okay, maybe “thrilling cliffhanger” is really “slightly more interesting than someone’s Grumpy Cat Internet Meme”…
I had discussed with my employer (ISSPRO) the possibility of bringing the chassis to work. This would serve two main purposes:
1) I could sneak back on breaks and get in some work on it during the day, and
2) I could avoid the inevitable frostbite-countering warm-up breaks from working in my freezing garage, and the potential of toe amputation from said frostbite.
In addition, I would have more workspace (it was starting to get cramped as the chassis is growing to full length), I could use the forklift for lifting & rotating the chassis to weld underneath, I could use one of our Bridgeport mills for machining brackets, and I could pick my daughter up from school in the afternoons (I’m a single dad with custody) and come back to work on it in the evenings. The plan was to work while she does her homework in a nearby office and I am available to verbally help her while continuing the fabrication process. That last part hasn’t worked out quite as well as planned, with Caitlyn usually wanting to hang out in my office (where she spends more time doodling on my whiteboard than actual homework).
I decided to transport the chassis & the jig clamped together, figuring the chances of both making it intact would be improved with each reinforcing the other. Of course it also meant trying to move a nearly 2000 lb bunch of steel without wheels by myself! I jacked it up in my garage and placed it on wheel dollies:
I considered transporting it in my enclosed trailer, winching it up the ramp door, but my sloping lot would require me to get it up my steep driveway first (and I was working alone on a rather cold day). I decided to use my flatbed trailer with sideboards on to help hold in all the other crap I would be bringing.
I wheeled it up to the trailer, then used the floor jack to get the 1st end onto the trailer.
I forgot to take a picture of it, but I had previously been using the trailer for hauling firewood, and hadn’t cleaned out the small pieces in a while. They formed a pretty big layer on the floor of the trailer, which was now frozen solid. I ended up spending an hour in the freezing weather chipping away at the pile so I could see the floor again.
At this point I used an old trick from moving safes out of grocery stores (dismantling the stores, NOT stealing the safes ). I used a couple of pieces of tubing as rollers, between the jig and the floor of the trailer. This was why I had to get the floor cleaned up!
Once I had the 1st roller up there it was relatively easy to push it up by hand.
After tying the jig & chassis down I packed in all of the remaining tubing, plus my welder, Argon bottle (securely strapped to the chassis), and a bunch of other tools.
Of course the door to the spot where they cleared out for me to work on it was a pain to get to (one of those spots where it takes a complete jacknife of the trailer), but I did it.
Unloading was just a reverse of the loading process. I thought about using the forklift, but it would have meant effectively “painting myself into a corner” backing the lift into a spot up against some machinery.
Of course my luck with this project continued. The next morning after moving the chassis and tools, there had been a forecast for possible light flurries. Instead what we got was a 5 day “Snowpocalypse”, which would have barely slowed a Northern or Midwestern city but paralyzed our city. My plan was to use my old ’73 Blazer to get into work (if it got too deep for my Jetta with snow tires & chains). I verified that my Jetta could not make it on the hills around my house and turned to the formerly trustworthy Blazer. That night I parked it with its nose and windshield under the overhang of my camper, thinking I was being smart and keeping the snow off of it. When I went to fire it up in the morning it would not start, and it was so pinned in that I could barely open the hood. After pushing it back as far as I could by hand, I was able to swap a bigger battery in, and discovered that it was not getting spark. It turned out to be a failed electronic ignition module (GM HEI distributor), and with the Pontiac 400 engine swapped into the Blazer it is a VERY tight fit working on that distributor even if you can get the hood all the way open! I was able to replace it working by feel (crammed into the claustrophobic space under the barely open hood). By this point I had burned up 3 days of the Snowpocalypse, spent another day sledding with my daughter to make up for it, and finally got to work on the chassis again!
With the mounting points for the right front suspension mostly complete, I moved to the left front and started with a pair of jig support bars precisely placed and tack welded down.
From there I precisely placed and tack welded the “dummy” bars for holding the lower control arm brackets in precise 3D space and angle.
At this point I discovered that making the 1st two of those brackets from my 3D model measurements (back when I was making the ones for the other side) was not such a good idea, with minute differences between the real world and my model.
The material for the brackets (like everything else on this chassis) was 4130 CrMo, but in this case it was a strap 3/16″ thick & custom width to get the optimal size to get full engagement with the tubes and angles in question. Fortunately when I custom sheared these strips from plate stock I made extra! And since the four pieces are varying lengths, I could replace the longest one and use each piece to replace the next shorter one while leaving me enough length to get a precise zero-gap fit-up.
While intermittently fitting up those pieces I also welded the remaining supports on the right front strut upper mount, just welding 3/4″ at a time to avoid weld draw.
The front outside mount in this picture was the most difficult one to fit with its weird compound angles, but I just went VERY slowly with metal removal until it fit!
The rears were a little less work since the angles weren’t as severe.
At this point I was ready to start tacking them in place:
Unfortunately it was also time to lose another week on the project, as ISSPRO is displaying at the ConExpo trade show all week in Las Vegas. Thankfully this show is only once every 3 years, but of course it had to fall right as I was starting to make good progress again! I guess I’d better make sure to finish the project before the next ConExpo in 2017!!!
The ConExpo show was great, except they have the show go through Saturday. At all 4 of these I have worked at, it is completely dead on Saturday. I sure would have rather been back at the shop working on the race truck!!!
Once I was back, next step was to fully weld the left strut control arm tabs (they were tacked in place before I left for the show).
After triple checking that they were positioned correctly, I removed the jig fixtures which had been holding them:
At that point I welded in between the brackets, which was time consuming as I swear that puddle would jump up and contaminate the tungsten each dang time I started an arc! I spent waaaay too much time resharpening tungsten at this point!
Next up I added gussets, and finish welded the gussets on the other side.
While contemplating whether to sharpen more tungsten or call it a night, I realized that I needed to cut off the top door hinge on this side, to make room for the main strut support bar.
At that point I had another interruption in the progress, as it was time for the NHRDA season-opening event in Bakersfield, California. I had really hoped to have this truck done in time to race there, but I wanted to at least go down and support our customers, and hopefully score some points in the Sportsman ET class in my dually. I managed to make it to the quarter-finals before hitting the brakes too hard and losing by 0.01 seconds to my friend Dustin Gullet of ATP Trucks.
That event was the start of Spring Break, and my daughter was spending the whole week at her mom’s house. I looked forward to late nights filled with lots of progress, but managed to catch a really bad cold (presumably from one of the dozens of people I talked to in Bakersfield). I suppose I was due, as I had managed to avoid colds & flu for well over a year.
Next step was to add the fixture for holding the front hub in place. This is one of the critical measurements of the chassis, so I checked and adjusted many times to get it perfect. One trick I did was to make a dimple in the plate 180° out from the top bolt hole, but on the bolt circle. I could position by that dimple mark, then make sure it was exactly vertical with the centerline of the top bolt hole.
I had pre-drilled pilot holes in the angle that mounted to the jig, then clamped it firmly into place and drilled through both surfaces with a bit that would be a net fit with the 3/8″ bolts to hold it together. I wanted zero slop once bolted up. Once I had that all together I assembled the strut and bolted the hub up to the plate.
I used the control arm tubes I had already precisely cut for the other side, and adjusted for slight variations with the rod ends.
At this point I suddenly realized I was kind of “painting myself into a corner”, as I planned to add a front crossmember in this area, and it would be a pain to slide it past the mounts once the main strut support bar was in place. As much as I hated taking a step backwards, I disassembled the precisely positioned lower control arms and lifted the main frame tube out of the jig, so it could be flexed over to install the crossmember.
With that done I reassembled and adjusted the control arms, then added the upper strut mount:
Fitting the strut support tube was a pain, both having to be notched to clear the control arm mount, and being positioned in 3 dimensions at 3 different points (lower front, upper rear, and center with the strut upper mount).
After what seemed like a thousand test fits and adjustments I finally had it ready to tack in place. I used a clamp to help the magnetic mounts that I usually use to help hold tubes in place, so I could be sure it didn’t slip wtih the repeated test fits:
While tacking the upper strut mount I remembered how much hassle I had with the other side moving around after I removed the strut and bearing from it, as the instructions were very clear to only do the smallest of tack welds before removal or risk damaging the bearing & strut. I decided to try a slightly different approach, and kept a soaking wet rag over those parts so I could put a much more robust set of tack welds:
When it was time to remove the bearing, I realized that the socket I used to press it out before was pressing on the bearing spherical portion rather than the outside race, so I needed a very precisely sized tube to do it instead. Fortunately there is a big metal lathe at ISSPRO, so it was quick work to turn down a piece and use it to press the bearing out and finish the tack welding:
Another trick I learned was to use clamps near the weld when welding around tubes otherwise “out in space”, to give my hand a steady spot to rest on while welding. It made me much less likely to contaminate my tungsten, which was a welcome change since I had spent so much time sharpening it so far! Now if I could just get my daughter to sharpen my tungsten for me while I keep working…
I swear there is always something that keeps me from spending time on this build. In this case I lost a few days to clearing up a case of ID theft! I went to file my taxes and found out that someone had already filed a fraudulent return using my information. It turns out that a large percentage of people who volunteer for Catholic schools in our part of the country had this happen, apparently by someone in the company they used for the legally required background checks. Too bad they couldn’t have paid the tax bill I actually had due!
After filing tons of reports, I went back to the chassis and quadruple checked positions on everything, thenI finish-welded the left side strut support bar:
Next up I welded the left upper strut mount with its gussets:
The plans from Chassisworks called for the crossmember for mounting the steering rack to be about 1.5″ higher than the bottom main chassis tubes, so I couldn’t just tie between those tubes like the front crossmember I previously installed.
My plan was to add a couple of angled braces from the main frame rails to the strut support tubes, both to reinforce the strut mounts, and to give me a spot to tie the steering crossmember to. Unfortunately the strut tube and the main frame rail are at a compound angle to one another, so it is VERY difficult to fit the tube to both sides. I managed to notch the first tube a little too far, and had to start over. Good thing I have some extra tubing!
After I test fit that tube I suddenly realized that even a slight change in the position of the steering crossmember would change the length & angles on this tube! I decided to fixture up the position of the steering crossmember to be sure.
As I was starting to test fit the steering crossmember I realized that since the bottom of it was just below the top of the main frame rails, it would require a double notch on each side.
Since all of those dimensions and angles would change with a slight change in position, I used a shorter piece to make a temporary steering crossmember, so I could make sure the steering rack position was perfect.
I clamped it into place on my previously added jig fixture:
At this point I was relieved that I had done all of this as a mock-up, as the dimensions for the steering mount placed one side too far outboard, where the clamp would hit a bulge in the rack that was there to hold the boot:
I remember the Chassisworks tech guy telling me that they don’t make the steering racks themselves, and it has been getting harder and harder to find a place to build them. It appears their current supplier has the dimensions a little off from the original Pinto application that used these.
Now for a little boring sidebar on steering geometry:
The most critical part of all of this is eliminating what is known as “bump steer”, you need to make sure the front tires do NOT change direction even the slightest bit as the suspension goes through its full articulation. In order to accomplish this the pivot point on the steering needs to be perfectly aligned with the pivot point on the lower control arms, and the height such that the steering tie rods are parallel to the lower control arms.
I decided to pull both boots so I could see for sure where the pivot points were. Sure enough, even with the steering rack centered as far as its travel, I needed to move the whole thing 0.5″ to the side (in addition to moving the clamp mount as mentioned above).
At this point I really needed the control arm & strut assemblies together so I could check the aforementioned parallel requirement. I pressed the bearings out of the lower control arm ends:
The tubes needed to be drilled for rosette welds:
I just tack welded them together for now, in case I need some adjustment in length. While there is adjustment in the rod ends, I want to start out with them right in the middle of their adjustment!
As I went to assemble everything, I pressed the spherical bearings back into the A-arms without too much effort, but when I went to press the bearings into the upper strut mounts I found that the weld distortion made it so hard that I was bending the biggest C-clamp I had! This was even after freezing the bearings! I was prepared to heat up the sockets as well, but decided to come up with something different for pressing the bearings in. I ended up using some specific cut sections of tubing with a 3/4″ fine thread grade 8 bolt, which had the secondary effect of forcing everything into alignment as it pressed it together. No need for heat as this pulled the bearing right into place.
I used shims between the control arm and the jig to hold the strut assemblies exactly at ride height, then measured off where the updated tie rod tubes and the original tie rod shafts needed to be cut in order to weld them together.
I learned that this was another area where the reproduction Pinto rack was different than the factory ones. This one used a MUCH larger diameter tie rod shaft than the originals, and the originals normally fit into the tubes I am supposed to weld them to.
I made the cuts, counterbored the tubes (they were counterbored for their ends, but needed to be rebored since I was cutting them so short), then used the lathe to cut down the tie rod shaft diameter to where it would fit:
Now I should be able to tack everything together and verify that the steering geometry holds up throughout the suspension travel.
To start out, I wanted to give a shout-out to Hughes Performance. Early in this build I had decided to use their XP-5 Lockup Pro Mod Powerglide transmission, which was the most expensive of the options I was considering, but was rapidly achieving a track record of being the most durable option out there. When I bought it, they told me to keep in touch with them since this was a new design for them, and they may have updates to the design periodically. My cynical side was thinking “sure, come up with more ways to charge me more money”. As I was getting closer to having this truck completed I decided to contact them to see what updates were available (and whether I could afford them). To my surprise there was no charge, and they took care of everything. One significant change they made was to switch to a larger steel bellhousing, which allows the use of larger torque converters. This has been necessary to hold the increased torque of compound-turbo engines (their earliest test units had used parallel charger arrangements).
Back to the chassis and the steering. I drilled the tie rod extension/adapter rods for rosette welds, then tack welded the tie rods together, assembled them back to the steering rack, clamped the rack into my jig location, then assembled the rest of the steering:
With the suggested position from the instructions, the tie rods appeared to be parallel to the control arms:
For measuring toe-in, I bolted some aluminum tubing to the caliper brackets (which stay parallel to the rotors). The tubing was much longer than the diameter of the wheels (where toe-in is normally measured), which would magnify any toe-in problems. I can scale the toe-in changes back to the dimensions of the wheels for comparison with known standards, but I wanted a very precise measurement as I adjusted things to minimize the toe-in changes.
Checking the suspension at various heights, I found that toe-in changed an unacceptable 0.26″ through the full travel.
Consulting a couple of chassis building books, they recommended dropping the rack position with such a result. I dropped it 0.445″, then reassembled and remeasured. Visually the tie rods looked almost too low, but I verified that they did not come close to contacting the control arms at any position or suspension articulation.
The result was a total toe-in change of 0.036″ (well below the 0.060″ that the books recommend as a target).
At that point I went to fit up the angled braces with the revised position of the rack crossmember. Remember when I mentioned trimming one too short before? With the repositioning of things it ended up almost the perfect length, just needing some minor trimming.
Remember that I had cut a longer one and began fitting it? It turns out there was enough material to change the angle at the top to its mirror image, and use it for the other side!
I guess I was too excited from all of this reusing of parts, when I clamped the 1st brace into place and tack welded it, I tacked it on the outside, such that the weld draw of the tack weld started pulling it away from the mating tube on the other end.
This required using my good old friend the ratchet strap to hold it in place to weld the other side! After that I remembered to tack on the side where the weld draw will help hold the bar in place…
I welded around on the inside of the tubes at the top, but avoided the outside until I removed the spherical bushings to keep from damaging them with heat.
With no such bushings close to the bottom of the braces I was free to weld them all the way around, but still only welded about an inch at a time to prevent excessive weld draw.
As I was doing that I suddenly realized that I had forgotten to drill vent holes to allow the gases to expand into the adjoining tubes! Fortunately I would have the crossmember covering the lower end of these braces, so I was able to sneak a hole in down near the end, and drill all the way through to the tube underneath so the gases can still flow when I weld in the crossmember.
With the holes in place I was able to fully weld around the tubes (after removing the struts and the spherical bearings to protect them from heat damage).
While those welds were cooling as I did the aforementioned skip welding around the tubes, I decided to try removing the threaded rods I had used to brace the 4-link brackets while I welded them into place. This turned into a classic case of painting myself into a corner! I had sorted the nuts to find ones with the exact width (with two stacked together) for the inside dimensions of the 4-link brackets, then carefully threaded them together when the brackets were still separate pieces. This worked great for holding everything steady while fitting and welding, but now that they were one piece it provided a bit of a challenge!
The first one I had done a while ago, and it took waaay too long. Literally it was like working a stout locknut (that took probably 80 ft-lbs of torque) for about 3′ of threads, where you had to turn one pair of nuts one flat, then the other pair one flat, over and over a few thousand times. This time I decided to cut the rod in half, figuring I could then just thread it out the short way (maybe 3″ of threads). I had to use a piece of sheet metal to let the ends at the cut pass each other while I did the 1st side.
This actually worked pretty well, but of course it still ended up a mess as I was trying to do the remaining half, one of the nuts stripped. I had maybe 3/4″ to go, but it will just get cut out with the angle grinder now. In retrospect, I probably wasted $50 of time saving $10 worth of threaded rod!
While doing this “outside the box” thinking I realized that I could always move the rack mounts slightly lower and use shims to bring it to the optimal height. However the position was already against the top of the jig crossmembers I had placed for positioning the rack crossmember. Who says I can’t modify those crossmembers? I trimmed out the top surface and ground the edges down to a specific height, to allow a little more adjustability in the rack crossmember position.
As I do the final rack crossmember mounting I will see if I can find a spot that yields less than the 0.036″ of bump steer.
Before I get too wrapped up in this update, I have to throw out a pic of something I have been looking forward to a long time, my daughter and I managed to both win at the same event (and I also got a perfect light during qualifying, earning me the #1 spot and a T-shirt).
Yes, I know the plaques and shirt are being held upside down, it was my daughter’s idea to make the photo more interesting.
The general theme of this update is that there have been more cerebral than physical accomplishments lately. As I approached some of the remaining details of this chassis I decided to spring for the 2-book set from Jerry Bickel Race Cars covering chassis construction. I considered buying them before, but IIRC they were close to $400 for the two books. They eventually lowered the price AND had a sale, so I picked them up for $120.
A large portion of the books covers the weird little details that I had to learn for myself and documented in this build, such as drilling pressure relief holes. They do give a lot of tips on areas I still have to do, like brake pedal and master cylinder mounting, and interior tinwork.
Speaking of brakes, I picked up a couple of master cylinders (plus a spare to keep in the trailer).
Most of the aftermarket braking companies use master cylinders based on the Chysler design they used on their mini vans and some pickups. I just bought Raybestos versions of the Chrysler parts.
I resurrected the 3D solid CAD model of the race truck so I could figure out where to place a number of components.
I started by adding some gussets to triangulate the firewall. This is a critical area, as this is where the torsional load from the drivetrain is transmitted into the chassis. However, I still needed to leave plenty of room for the up-pipes to pass through and up to the high pressure turbo.
Next up I needed to figure out the angle and height of the engine/transmission combination. The overall goal is to aim the output of the transmission directly at the yoke of the rearend. I also wanted enough ground clearance to use a standard Duramax lower oil pan. This required a 2.9° downward angle in the chassis.
Next up I needed to model the outside surfaces of the transmission, so I could figure out how to build the tunnel and the transmission crossmember. I just simplified the shapes into stepped cylinders and a partial donut shape for the bellhousing.
I was worried about how I was going to squeeze the fuel cell and dual batteries in the back, but eventually worked out a plan.
I originally planned to have the transmission mount come up from the existing floor crossmembers, so I added them to the model:
I ended up deciding on a simple additional crossmember to go between a pair of double frame rail uprights. Since there is not a significant load on the tail of the transmission (the torsional load is carried by the midplate), this can be a lightweight crossmember.
One of the next key items was figuring out how the brake pedals were going to mount. I finally decided on a stationary shaft which would be clamped to the chassis, with each pedal having roller needle bearings where it rides on the shaft. I can use simple spacers to move the pedals side to side until I am happy with their position.
My plan is to hook the left pedal up like a normal brake system, and the right pedal will be dedicated to the 2nd set of rear brake calipers. When I am building boost before bumping into the beams I can straddle both pedals with my left foot, getting as much braking force as possible.
Probably the single item in the build that I put the most detail into for the CAD model was the master cylinder. With its complex shapes and the tight fit with the floor crossmembers I figured I needed all the detail I could get.
Once those were positioned I designed a crossmember to support them. I tried two versions, one was made from 1″ x 1.75″ rectangular tubing with cutouts, but the final version is using 0.125″ plate stock. I ran the calculations for which one would be stronger, and this one won out (although they were close). I figured this one would be easier to build as well.
All of this CAD work makes me want to get my hands dirty on the real chassis! I added two more diagonals to support the upper strut mounts, and to tie into the front engine mount plate (this was another reason to get that CAD work done so I could figure out where that plate would end up).
Once those tubes were fully welded I pressed the spherical bearings back in and reassembled the steering, so I could fine tune the steering rack position and minimize the bump steer.
At this point I realized that part of the jig was hanging up the struts and preventing them from fully extending. My previous “success” at finding the optimum rack position turned out to need some fine tuning. Once I removed the jig section that was interfering, I had more front end travel to contend with!
With this additional travel I had more potential toe-in movement (bump steer) than I thought. I ended up fine tuning the rack position and getting it even better than the “short stroked” result I had before! Total toe-in change through the full travel range is now 0.02″ per side, and through the main travel range it is zero!
I was hoping to have the steering finished in the chassis and the rearend at least temporarily mounted, to have as a display at this weekend’s NHRDA Pacific Coast Diesel Nationals Presented by ISSPRO (yeah, that is a mouthful to say OR type). However, I decided to keep focus on the build rather than trying to get it off the jig and out to the track. Don’t let that stop you from coming out to Woodburn Dragstrip on June 28th to see a great show of diesel racing and sled pulling! There will also be a lunch served compliments of ISSPRO. Hope to see you there!
Sorry for the lack of updates, too many things going on between work and other racing, but finally getting more time on the race truck.
First off, a belated “Thank You” to all who attended the Pacific Coast Diesel Nationals Presented by ISSPRO! While we had scorching heat in prior years, this time we had torrential downpours, but somehow squeezed in the racing and sled pulling between rainstorms. We still had a huge crowd of spectators who braved the rain to cheer on the competitors.
A few details on the other items:
My Vega, which has always hooked really well (once I had the suspension all dialed in) suddenly started spinning the tires badly, and it turned out to be the original Koni shocks finally getting worn out. I picked up a set of QA1 double adjustable shocks and got it working well again. Just as I was fine-tuning the new shocks, it suddenly started spinning again. I was able to fine tune it and pick some ET back up, only to discover the slicks were down to the cords! I guess the suspension is REALLY working well to be able to hook up with cords showing!
My next fiasco was at a race with a really bad crosswind at the top end of the track, it ripped the scoop off on one pass, and blew the driver’s window out on another! Weird crap to be happening at 147+ mph! A couple other cars had their side windows blown out too, including one with original glass that made a huge mess on the track.
I ended up trading some parts for a complete Vega hood with scoop, and made a new side window.
Back to the race truck, I started working on the steering mount crossmember, which was positioned at a weird compound angle (and offset from center) of the diagonal strut support bars.
I used a spacer and longer bolts to allow me to do the offset notching on the tube:
Of course, after carefully notching one side, then carefully measuring the other side (keep in mind, the length of this tube varies dramatically with its height since it is dropping between angled bars), I was horrified to discover this gap:
And of course it was the last piece of tubing I had in that size! I really hate ordering only one piece of tubing, with the associated shipping charges!
As I waited for my replacement tube to arrive, I notched and fitted the rear vertical bars that tied in some of the rear suspension, and would be the anchor point for the double frame rails:
Fortunately I remembered a lesson from earlier in the build, when working with weird compound angles like this: I used my properly-notched but too short piece of tubing to make a card stock template. If I would have planned better I would have used a short scrap of tubing to rough in the notch, but hindsight is 20/20!
After marking and notching the new tube I was able to get a nice snug fit:
I had precisely positioned the height of that tube with shims, after adjusting it (and leveling the steering rack mounts) when adjusting for bump steer (detailed in the last entry). I went ahead and fully welded this tube in place:
Next up was positioning the rack mounts. Rather than just making them perfectly level, I had a sudden epiphany that I could precisely adjust the height of the rack at this point, perhaps getting even less bump steer in the process. I bolted back on my bump steer checking apparatus, and used some threaded rod to make very fine adjustments:
I also marked the extremes of the rack steering travel so I could line everything up with the rack perfectly centered in the chassis:
With those adjustments done I was able to get the total bump steer below 0.01″ per side through the entire suspension travel!
Next up I tacked then finish welded the rack mounts in place:
Next project was to fabricate some tabs that would serve the dual purpose of gusseting the top strut mounts, and providing the top mount for the front suspension travel limiters.
I mocked the pieces up in cardboard first, using long threaded rod to make sure they were perfectly aligned with the point on the lower control arm where the limiter cable would eventually attach.
I used the cardboard to mark and cut out the metal pieces:
Next up was the initial fitting and tacking of the metal piece, where I discovered that the cardboard flexed just a bit more, requiring some additional cutting on the metal:
Next up will be wrapping up these mounts, then moving on to the double frame rails.
After maneuvering the gusset/mount into a few positions, I figured I would tack it, weld it, then cut off the excess;
On this side I welded it in several short beads (making sure to not overheat the bearing in the nearby strut top mount).
On the other side I was in such a “groove” with a nice bead going, I forgot to take my time to keep from heating up the bearing! I immediately wrapped a wet rag around the bearing to keep it cool.
After that it was a simple matter to trim the excess, and test fit the eye bolt:
My next big delay in the project was the SEMA trade show, our biggest event of the year. We discovered that all of our table-top gauge displays from prior years had been destroyed in shipping, so it was a mad scramble to make more in our 3D printer and get things set up.
We had a great show, highlighting our new datalogger as well as our new line of waterproof gauges (displayed to the right in a fishbowl complete with live fish).
I got to hang out with my old friend Steve Darnell, star of Vegas Rat Rods on the Discovery Channel. We had a fun time playing with the welding simulator at the Lincoln Electric booth.
I also got to spend some time hanging out with my buddy Aaron Hagar, as well as his new business partner Brad Fanshaw (TV host, former BMX racer & executive, and Boyd Coddington protege’).
Our booth was so busy all week I swear everyone on the planet must have stopped by. Even Elvis, who seemed more interested in our sales associate Jen than in any gauges…
After all of that I finally got back to the race truck and its double frame rails. Double frame rails are seen on higher powered Pro Mod type cars, but with the torque of a diesel they have become necessary even for something running in the 8′s or 7′s, as several of the original NHRA Pro Stock Truck chassis (which are not double frame rail) have seen issues with the torque of a diesel.
Fortunately the first steps included 10 different tubes cut and notched identically. I could finally feel like I was making progress in more of an asssembly line approach, making 10 identical parts. Sure, I still had to swap hole saws (different sized notches at each end), but I’m sure that is the most cuts I have made with my notcher without adjusting the angle!
Even the metal prep (removing mill scale from inside and outside the tubing at the ends) was seemingly easier since I was doing so many at once.
I prepped all of the matching spots on the chassis for each of these vertical supports for the double frame rails:
While I was at it I went ahead and drilled the pressur relief holes for both these tubes and the upcoming diagonal tubes. I have a bad habit of forgetting those holes!
I even got carried away with my prep and hole drilling on the top rails of the double rails, as I forgot about the length loss due to notching, so I will probably be re-drilling those holes (and welding these ones shut).
I started with the two end vertical supports, wanting to make sure they were perfectly vertical, then using them as a guide to position the remaining tubes:
The next tubes sometimes needed some “adjustment” in their position after tack welding them in place. This was accomplished by placing a larger diameter tube over it, and applying some good old fashioned brute force:
Hopefully when I am done with all of the vertical supports they will align perfectly with the top tube of the double rails. Then I will get the fun task of carving a weird shaped notch in the end of each of those rails, where it intersects the strut tube right at a bend! Hopefully I have a scrap piece long enough to use for that, so I can use my trick of carving it to fit then making a cardboard template!
I was nearing the time to order more 1″ tubing to form the structure of the firewall, so I got back on the CAD system to figure out how the plates of the firewall would be positioned, so I could order that material at the same time and save on shipping.
With the amount of engine setback (necessary for good weight distribution with the heavy diesel engine), I would have the plane of the flexplate/flywheel at my shins, and my feet would be next to the rear portion of the oil pan (where connecting rods occasionally peek out like a metal groundhog on steroids). To keep from gaining the nickname ‘Stumpy” I want the vertical portions of the “footbox” section to be 0.125″ 4130 plate. The horizontal and angled portions will be 0.080″ thick 4130, still much more protection than the required 0.024″ mild steel.
The top area of that center section will be protecting me from shrapnel in the event of a high pressure turbo failure, so that part is important too!
While I have been happy with the freeware 3D CAD program (FreeCAD 13), it does have a few shortcomings and bugs in it. It is very easy to create rectangular and cylindrical shaped solids, but to get the triangular shape to fill in the opening in the above picture, I needed to cut two sections from a rectangle. Once I tried to rotate the part in space it would screw up the cuts. I finally figured out that it could rotate the part if it was part of an assembly or “union” but not by itself, so I created a little speck of dust (0.01 mm cube) that I “assembled” as a union with my desired triangle, then it allowed me to rotate it into position. I had to repeat the “union” process to rotate it about another axis, but it all worked out.
Now that I had all of the plate sections worked out, I needed to figure out how to best fit those shapes into a single plate of material, so I could minimize the material and shipping costs. I switched over to the 2D CAD program and played around with the shapes like a giant puzzle, moving them around until I had the least amount of wasted material.
I plan to use my plasma cutter for the necessary “jagged” cuts, but then use a big metal shear to make the straight cuts.
While I was doing all this CAD work I decided to go back to the seat mount design I was working on before. I had previously designed mounts for the master cylinders and brake pedals, and had placed the master cylinders as far back as possible, figuring I would want more of an open floor in front of the seat.
Unfortunately this placed the seat mounts directly over the master cylinder rear caps, and compromised the geometry of the mounts. It was a lot easier to move these in CAD than it would have been after welding! I just moved the whole assembly forward 50mm and gained the clearance I needed.
Continuing on the double rails, once I got to the intermediate vertical tubes I used a ratchet strap and clamp to squeeze the top tube down, hopefully holding everything in alignment.
I tried experimenting with that approach versus a “freehand” approach using the digital angle finder like I did the end ones, it was almost a toss up between the time spent setting up the clamps and tube versus taking a little more care with the angle finder and quickly moving from one side to the other on my tack welds (so the weld draw on each side could pull against each other).
I ran all of the truly vertical double frame rail supports (5 of them) on one side, then did the mirror image on the other side.
The “vertical” supports that coincide with the engine mount front plate and the mid plate will both be slanted back 2.9° from vertical, to match the slope of the engine/trans (so I have full engagement with these tubes when I weld brackets on at that 2.9° angle). Since the digital protractor was referencing horizontal instead of vertical, the 2.9° angle shows up as 87.1°. And you thought you would never use geometry again after school…
All of those vertical braces were much easier to insert into place with the top rails not welded in yet (as they would require separation of the bottom and top rails to “pop” into place). In this photo you can see the 2.9° tubes, where the front plate of the engine mount will eventually go.
On all of these tubes I was tacking in four opposite spots, to keep the tubes securely positioned. Due to weld draw, I will wait until the whole assembly is tacked together before finish welding it.
Before I got too far I decided to verify that I had the planned clearance between the seat and the double frame rails. While it is nice to lay this stuff out in CAD, I always feel better when I can see the clearance in the real world!
The front edge of the top double frame rails shows the weird compound angle I will have to notch next. Not looking forward to that one!
Of course when things seem to be going well, something weird has to go wrong! This was a weird freak occurrence but something you have to be careful about when working around hot items and a roll cage! I had just finished a weld in an awkward position, went to climb out of the cage and smacked my head & welding hood on the top of the cage, which swung the hood down over my face just as the still-red-hot filler rod caught one of the double frame rail tubes, flipping its hot end right into my chin and under the hood (making it VERY hard to get out). I could hear the flesh searing as I tried to grab the damn thing, and it scooted along a nice straight line as I tried to extricate it!
Next up is the last pair of frame rail uprights, then the aforementioned nightmare notching of the top tubes, tacking them in place, then the 45° diagonals for the double rails. After that it will be on to the tubing forming the firewall, before I move the whole chassis forward on the jig to continue on the rear tubes.
Remember that 4130 chrome moly sheet and plate I was ordering for the firewall last episode? Apparently someone at AircraftSpruce.com’s shipping department has a sense of humor. Pretty sure even the worst UPS package manglers would have had a hard time hurting 4130 plate.
After all the vertical supports were in place I double checked their alignment. They looked like a couple of rows of little telephone poles sticking out there!
Next up was a task I had been dreading, the notching of the double frame rail tubes where they ran into a weird curve and compound angle. I started with a few rough cuts to get me close:
A little more work with an angle grinder and die grinder yielded a nice no-gap interface.
I used a piece of card stock to trace the shape from the first side, then reversed it into a mirror image and marked up the other side’s tube for cutting.
Rough cutting to that traced shape got me to a near perfect fit first try!
Next up was to carefully measure then cut and notch the other end of these top tubes, where they intersect with large vertical supports that form a “box” to help transmit the extreme forces of the 4-link brackets into the rest of the chassis.
Once the notching and fitting was done in the rear, it was time to cinch the top tubes down and begin tack welding it at all of its interfaces (10 of them at this point).
Once the tack welds were in place and I had verified that everything was still in alignment, I began finish welding the end connections, going an inch or so at a time (trying to avoid weld draw from too much heating). I also finish welded the areas that would be blocked off by the diagonals which were going in next. I need to avoid painting (or welding) myself into a corner!
I cut and notched the first pair of diagonals. I would have normally used the magnetic corner clamps to hold these tubes in place, but this spot was too small for them! A couple of spring clamps did the job (but being plastic I had to be careful not to melt them)!
As with the other tubes, I initially tacked the diagonals into place.
Once they were both tacked in I started finish welding both the diagonals and all the other joints in the double frame rails.
Some of these joints were a little tricky to get to, requiring me to either lie on the floor or on the bars that form the bottom of the chassis.
I struggled with trying to press the foot pedal of the welder up against the jig or chassis, but finally dug out a long strip of velcro to help me keep the pedal tied to my knee while I used the other knee to press the pedal.
This worked pretty well, but there were a few spots where I was too contorted to even work the pedal that way! At that point I switched over and used the thumb switch on my torch head. While this was easier to do in weird positions, it meant getting my amperage set perfectly on the welder (since I couldn’t modulate the amperage like I did with the foot pedal).
Joint by joint, I worked my way welding an inch at a time (usually splitting between two close together welds) until I had done all 40 of the joints.
About halfway through I finally finished burning through my first large argon bottle (after upgrading from the smaller bottles that I had been emptying too often).
Next up: the remaining double frame rail diagonals. I am beginning to see why so few race cars (and trucks) are built with true double frame rails. While they add minimal weight to the chassis while significantly increasing stiffness, they are a LOT of work!
I had a little bit of a side project to complete, as racing season was here and my Vega was no longer making the noise limits at our local track (they got a new sensor system which is apparently more sensitive). I had been running two Dynomax Bullet mufflers per side, but switched to a single large Magnaflow stainless muffler per side, with mounts and 90° ends turned to face each other under the car.
With some crude testing in my garage using a newly acquired noise meter, it appeared to drop my noise by around 3 – 5 dB, hopefully that is enough!
Next it was time to start the first of many diagonals in the double frame rails:
After the first couple of diagonals I started “mass producing” them:
Welding the diagonals in was a bit of a challenge, as I had to have my head way too close to the weld. I tried some reader glasses to help me focus on such close-up items, but they were more hassle than it was worth.
After way too many hours with my body folded up to where it would fit between tubes, I finally had all of the diagonals fully welded.
Next up was the start of the firewall support tubing. The “base” for all of this is a big diagonal on the passenger’s side firewall, to help counter the torque of the drivetrain as it is transmitted through the mid-plate. This tube intersects a point with several tubes converging, so the notching was a bit difficult:
This picture doesn’t quite do justice to all of the weird contours I had to cut in that tube to eliminate gaps:
The top side was a more conventional (and much easier) notch, aside from being a pretty steep angle.
And finally I could weld the other end in with its weird contours:
Next up was the first of many triangulating tubes coming off this main diagonal:
Unfortunately as I had tacked this one in I realized that I forgot to drill pressure relief holes! Fortunately another tube would connect across from it, so I was able to drill the pressure relief hole from that point and through both walls of the large diagonal.
At one point in this notching I realized that my notcher was allowing the notched tube to rotate, despite having the clamp screw so tight that it was deflecting. My solution was to carve a few longitudinal ridges in the clamp, which helped a bunch.
In the immortal words of Britney Spears, “Oops, I did it again”, I managed to forget another set of pressure bleed holes, but fortunately was able to drill across.
After many more tubing cuts, notches, tack welds, and finish welds I had the passenger’s firewall structure complete:
Now it was time to do the driver’s side firewall structure, which has a much different shape due to the opening for the recessed “foot box”. This required the first tube to just cantilever out from the upper frame rail at a 90° angle. This was tougher than it looked, getting it positioned just right then holding it while tack welding it (and fighting against the weld draw as the weld cools).
Now it’s starting to get more exciting for me, as I build the area that will surround me as a driver. Needless to say, I’m taking my time and not cutting any corners when it comes to protecting me!