Welcome to ISSPRO’s Performance Diesel Blog

Come view this page periodically to see updates about everything from upcoming ISSPRO products to updates on the build of my new race truck, racing results and the behind-the-scenes thrashes needed for all of the above!

Michael Pliska (ISSPRO Engineering Manager)

05/24/2013
Race Truck Build Report:

If you missed any of the earlier blog posts about this build, they are available here.

Episode 14:

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!