Unfair electronics device tray done

Welded Fab Boss

The device tray is fully mounted, taking 9 FabBosses — 2 on each side and one in the middle. Only the one in the middle took any real careful measuring — and that was because I couldn’t get my MIG gun all the way underneath the tray. All the other FabBosses were bolted to the tray, trimmed to fit, and tack-welded into place. Continue reading

No more bruises

They’re known as Corvette bruises.

They appear on the bony portion on the outside of one’s knees after a track day in a 6th generation Corvette and are because the factory seats don’t hold your ass in place well enough.  As a result — and without realizing it — you brace yourself against the door panel and the center console with your knees.  After a day or two of holding yourself in place like that, bruises develop.  It’s been a month since my last day on the track, and I can still find the spot where the bruise was by feeling for the painful spot.

As annoying (and kind of amusing, really) as the bruises are, the serious part of it is that not being firmly held in place by the seat is that you can’t drive as fast.  Too much energy is spent trying to stay in place instead of finding those precious tenths of seconds that add up to faster lap times.  And faster lap times is where it’s at… otherwise why be out on the track at all?

Gone are the days when you can bolt in a new seat, buy a harness and bar and bolt them into the car.  The C6 has a side-curtain airbag in the seat, linear sensors to know where the driver is, integrated telescoping steering column (both so the airbag can be deployed accordingly), belt pre-tensioners, and seat heaters.  Removing the original seat from all these systems and plugging in a race seat into its place, plus adding a 6 point harness is a daunting exercise.

The only good news is that most of the electronics are built into the seat track, and reusing that along with an aftermarket “airbag plug” — which fools the airbag system into thinking the original seat and its airbag are still there — solves most of the problems.  The challenge now is to find a way to integrate the original track to an aftermarket seat.   Available aftermarket seat brackets bolted to the factory seat tracks won’t work because they put the seat too high — and headroom is at a premium, especially when factoring in a helmet.

Armed with most of this information, I bought a used set of seat tracks from a wrecked Z06.  From there I made my own “low-boy” adapters to get a Cobra Suzuka GT seat (that I happened to have lying around — honest)  bolted to the GM seat tracks.  The pre-tensioner and factory belt work, since they bolt to the seat track.   I re-did the seat wiring harness to omit the heater and un-used side bolster circuits.   I have a Vetteworks harness bar on order to allow the use of a Schoth 6 pt. harness when I’m on the track.

Have a look at the photographs below to see how it all turned out.  I ended with a system that has nearly all the factory function, including all the original power movement minus the seat heaters and side-curtain airbag.  But the best part: this seat keeps me in place, letting me concentrate on driving.  And since I used a different set of seat tracks for this race seat, I can quickly swap it in for the track, and put the factory seat (and its airbag and seat heater) back in for cruising and ordinary street use.

Fuel Tank

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It’s been a while, but work on our Project Unfair is underway again. After my last project, I vowed not to ever use drag-racing parts for fuel delivery again. I was able to get that system to work most of the time, but eventually heat would cause cavitation, vapor-lock, and failure.

Instead, I worked with Carl Casanova at Vaporworx on our fuel tank. Unfair requires a wider range of fuel delivery than most cars since we’re expecting decent mileage while cruising, and 1200+ horsepower when running full-boogie for a quarter-mile pass or running the standing mile. As Carl calculated that means fuel needs range from 4 gallons per hour to 130 gallons per hour!

VaporWorx provides late-model GM fuel pump solutions to hot-rodders. These fuel modules, as GM refers to them, solve many problems. They are controllable by PWM (pulse-width modulation) and so can be slowed and sped up as the engine need changes. They also provide reservoirs to reduce cavitation, and can be hooked up to Walbro venturi pumps to literally be able to pump fuel to the last cupful in the tank.

Most of VaporWorx setups use a 5th gen Camaro pump, but that’s not quite up to the task, so we stepped up to a CTS-V pump. And that wasn’t enough, so we’re running two! VaporWorx has made some tweaks to their programming to support dual modules, along with setting a ramp-up method to support our crazy need to run 18 pounds of boost on race gas. Boost works against the fuel injectors: as the pressure increases, the injectors have to overcome it, so higher fuel rail pressure is needed. The VaporWorx controller takes all this into account. It’s an awesome solution to a difficult problem.

I built a fully-custom aluminum tank with dual pump module rings, fuel level sending unit boss, fill port to use a 67-68 style gas cap, vent, and drain ports. I’ll also be using our unique fuel tank vent/baffle along with a non-vented cap to control fuel slosh and gas fume emanation.

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Floating Away

I’ve just finished up a major sub-system on our Project Unfair: our floating rear axle setup. It’s all about fixing the phenomenon of “knock back” , where the pedal goes to the floor after hard cornering due to rear axle deflection pushing the brake pads away from the rotor. Our Unfair solution is to use a circle-track full floating axle setup where the axle is de-coupled from the wheel hub and the rotor. Using some custom machined parts, I’ve hooked up Wilwood’s 14″ rear brake setup with a Moser GN floater. I still have some work for a parking brake, but this setup will completely prevent any knock back issues.CRW_2091.jpg

Welding Center

I’ve been using my new Miller welders for about a month now. I’m pleased so far… the Dynasty 200 DX TIG machine has an amazing arc and the foot pedal felt natural from the start. I’m also applying my new knowledge of proper setup when using a gas lens (use 22 CFH rather than 16ish). Now I can use a tungsten stickout of an inch with no problem at all. Check out the size of the machine in the photo below. It weighs less than 50 lbs, and can be carried to the job site. It will even work with 110V if needed. I still haven’t tried it out on aluminum — which is why I sold my Lincoln to step up to this machine in the first place. That’s going to change soon: I’ve got a fuel tank to make in a couple of weeks.

My new Miller MIG machine (Millermatic 211) was a bit more trouble. Using the factory setup wasn’t working — I was struggling with burnback (where the wire melts at the torch end and not in the weld puddle) until I read on the Miller welding forum to turn up wire speed about 20% when using .024 wire (which I was). Now the machine is rock-solid and works perfectly. The low-spatter claims seem to be true as well.

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Two U-joints are better than four

I’m working on getting the human interfaces fabricated on Project Unfair and I just finished mocking up the column connection to the steering servo. Wilwood pedals are coming next, or possibly mounting the seat. The neat thing about this steering shaft is that my original design used 4 U-joints with the steering shaft under the motor mount, but Tim Christ at Coast Chassis Design (the gods of 10.5 racing over in Daytona Beach) convinced me to look into rotating the rack so the servo pointed above the motor mount.

So I did, and here’s the result. A very clean 2 U-joint steering mechanism. Good stuff. This photo is of the mockup with steel U-joints… we have ultra-cool aluminum versions from Borgeson on the way.

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