Here’s a big project that spread out over a number of months. I’m aggregated the photos here and attempted to make them tell a coherent story.
The cluster as a whole can be adjusted forward and back for drivers of different heights. The gas pedal is adjustable for foot travel, throttle cable travel and left/right position. The brake pedal height is independently adjustable, and brake bias is adjustable from front to back. The hydraulic clutch pedal is also independently adjustable for height.
Many of the original pieces were laser cut from steel, then bent and welded to form the complex shapes required. Some of the bushings were CNC turned, but most were made by hand. The master cylinders, brake bias adjustment cable, and the nuts and bolts were purchased, with everything else custom made. This includes the brake bias adjustment assembly, which forced me to learn how to cut threads on the lathe. It’s not as easy as it looks. Take a look at the brake bias adjustment bar– it has three sets of threads independently cut on a manual lathe, three diameters, two snap rings and a threaded hole. Good fun! Due to changes in the steering rack mount, the main pedal bracket had to be widened as you can see in the photos.
Laser cut parts arrive
Laser cut gas pedal parts before welding
Gas pedal parts clamped for welding. I like clamps.
Clutch pedal clamped for welding
Clutch pedal after welding and grinding
An early trial fitting
Testing fit inside the frame
Widening the main bracket
Finished main bracket
Lots of parts in primer now fitting together
Black epoxy paint
Finished except for brake bias assembly
New Chinese calipers: 2″ = 51.9mm LOLWUT?
Milling part of the brake bias adjustment bar assembly
I looked through a bunch of street car transmission shifter cables, brought a couple of them back to the lab, and decided on one that was the correct length, light, and low friction. Everything else was fabricated…
The car will use a Suzuki GSX-R1000 engine, which has a 6-speed sequential transmission, meaning the shifter only has two movements: shift up, and shift down.
Components of the shifter
Forward end of shifter cable with fabricated mount
Not much to say about this one… Just lots more piddly little brackets. The large bracket at the tail is necessary as that will be where the rear impact absorber will mount. Had to make some changes just behind the driver’s left shoulder to allow access to the fuel filler.
Sidepod brackets scribed from templates onto sheet aluminum
Sidepod brackets cut out
Sidepod brackets bent, ready to install
Locations are finalized with duct tape, then brackets are riveted
Sidepod brackets also hold the cockpit surround
Keel cover side mounting brackets
Keel cover side brackets riveted in place
A view of the keel, leg cover and nose mounts
Front cockpit surround and leg cover mounts
Rear sidepod mount
Rear engine cover mount
Right front engine cover mount
Left front engine cover mount
LF engine cover mount in place; side panel to be cut here for fuel filler
Upper tail mount
Tail mounts, separate from crash-structure mounts
Rear impact attenuator / absorber / crash structure mount
While the sides of the cockpit already have side-intrusion panels on the outside, they will also have a second panel on the inside to prevent the seat foam from extruding between the frame tubes and pushing on the outside panels, something those outside panels aren’t equipped to properly resist. The interior panels also must follow the SCCA rule against stressed skins that requires chassis attachment points to be more than 6 inches apart. Due to their different shape and size, the interior panels have a completely different mounting pattern and can’t share any of the exterior panel mount points. Thus, many more tabs are cut and welded on.
The seat back is formed by the fuel tank and three additional pieces of aluminum, shaped at the sides to provide shoulder support on the front while providing space and access at the back to the fuel pump on one side and the fuel filler on the other. The center section is removable to access the shoulder harness mounting points.
Test fitting the right side cockpit panel, view from inside
Left side clamped in place
Separate mounting tabs for interior panels
Left side mounting tabs welded in place
Left side cockpit panel installed
Test fitting the seatback
Seat back panel had to be cut in 3 pieces; right piece shoulder panel shown
Left shoulder panel provides access to fuel filler
Seat back center panel with shoulder harness cutouts
In my continuing effort to get everything welded onto the frame so can paint it, it’s time to build the floor pan. SCCA rules allow the floor pan to be a stressed skin, so this one fully welded around outside and to all crossmembers. To anyone who wants to learn to weld better, I recommend welding a floorpan. That’s a lot of welding. None of these pieces were laser cut– templates were made in plastic sheeting, transferred to sheet steel, and cut out with an angle grinder. Wear hearing protection. And eye protection. And lung protection. And heavy gloves up to your elbow. Angle grinders can mess you up.
The floor pan around front keel is of special interest. Some parts have a single curve which is easily fabricated, but two of the pieces have a compound curve which can’t just be bent. They have to be pounded into submission to make them fit. As this is my first attempt at metal shaping, I started out tentatively. After a lot of pounding I was getting nowhere and got angry. It turns out this is what you need to do. Pound the crap out of it, then fix the area around the big dent you just made, and eventually it takes shape. An English wheel would have been useful, but building or buying one is a big project.
There are two layers of steel under the fuel tank and the driver’s butt, one under the legs. Should be stiff, strong, and safe. And now, on to the photographs. I suffered through this. Now it’s your turn:
The firewall is a continuous, fully welded sheet of steel between the engine compartment and the cockpit. SCCA formula 1000 rules allow it to be a stressed panel, thus the continouous welding. Around the fuel tank it will be a double wall of steel for extra protection against engine explosions, insulated with shredded fiberglass to keep the fuel cool.
Priming the back of the fuel tank before installing the firewall
Finished fuel tank. You might want to wear sunglasses.
The fuel tank consists of an FIA FT3 certified fuel cell bladder, custom-made for this project by Aero Tec Laboratories, inside a custom made steel/aluminum container. The bottom and back of the container are made from a single laser-cut and bent sheet of steel, while the sides, front, and top are laser-cut and bent aluminum pieces. It’s carefully designed so the interior is completely smooth with all rivets and fasteners away from the fuel cell. All the rivet holes were laser cut also, meaning there’s only one way to fit it together– the correct way. This did make it very hard to install, however, as tolerances are zero to negative.
Inspecting or replacing the fuel cell bladder should be possible by drilling out all the rivets on the diagonal front panel and removing it. Not something I want to do very often.
The basic pieces: laser cut steel and aluminum panels, professionally bent
SCCA Formula 1000 rules require side-impact protection consisting of either kevlar laminated to the inside of the body, or 0.060″ aluminum or 18-gauge steel bolted to the frame. To keep the side impact panels from being used as a stressed member, attachment points to the frame must be more than 6″ apart. Mine are laser cut from 1.6 mm aluminum. The mounting holes were also cut by the laser to be sure of the 6″ rule, but this was a mistake as it made the mounting tabs much harder to fabricate. It would have been much easier to weld the tabs in place with holes already drilled, then drill through the tabs to the aluminum panels for exactly aligned holes. As you can see from one of the photos below, the panels fit perfectly. This project was a lot of cutting and welding with little apparent progress.
Cutting several mounting tabs at once
Left side tabs laid out and ready to weld
A simple jig to hold tabs in the right plane for welding
Amazing fit of the laser cut panels
Left side tabs done
Right panel. Note how panel was rolled over frame tubes.
The car will use standard Honda Civic axle halfshafts, and I had the choice of cutting, sleeving and re-welding them, or building extenders that effectively widen the differential to meet the unmodified halfshafts. The cut/sleeve/re-weld option would eliminate the axle hardening and leave unknown strength, and I’ve since seen an example where this was done and the axle broke right at the weld. The option of “widening” the differential has several advantages. First, we can easily replace the halfshafts if necessary in the future with off-the-shelf parts. Second, moving the inner constant-velocity joint closer to the plane of the control-arm pickup points minimizes the plunge, or change in length, required as the suspension moves through its travel. Third, the halfshafts become equal length, eliminating torque steer. Now you may say “but, the extensions will be of different length and will twist unevenly so the torque steer won’t be eliminated”. The extensions will be much stiffer than the axle shafts so that won’t be the case.
So the choice was clear. We started with a differential and a couple of halfshafts as raw material…