ChumpCar 1992 Lexus SC300

I went and checked the rules, for some reason I was under the impression there would be different min thickness requirements for DOM vs chromoly like in NHRA.

One last update for tonight. As mentioned, I'm planning to run LS400 calipers (and rotors) up front. The `95+ LS400's had all-aluminum 4-pot front calipers and something like 1" larger rotor diameter. Best of all, they happen to bolt right up to the SC300 hubs. I got a pair of calipers with pad, rotors and lines from the local pull-a-part for $49.26 total.

The biggest issue with this is the outboard caliper pistons require a lot of clearance with the wheel spokes so most OE-style wheels, including the BBS ones I plan to run, won't clear the calipers. To resolve this, I plan to run 1/2" wheel spacers on all 4 corners, which I'll machine myself. This, in turn, requires extended wheel studs.

The wheel studs really looked like a show-stopper because I wasn't willing to shell out something like $250 for ARP or HKS studs. Fortunately, China came to the rescue with some hardened extended studs that fit this application. They appear identical to the ARP and other name-brand units and I wouldn't be surprised at all if they were made in the same factory. Total cost for all 4 corners, after some negotiations with the vendor was a manageable $36 - not bad.

I didn't want to remove the wheel hubs at this point, so I brewed up a way to install these on the car:
The old studs were easily pounded out with a hand sledge. Here's a comparison of the old and new studs:
I fab'ed up a few simple spacers to check that 1/2 would be enough to clear the calipers and temporarily bolted on the new rotors/calipers.

Here's the wheel back on - clearance looks great. Got 1-2 mm between the spokes and the outermost part of the caliper, so I'll go ahead and get the actual spacers made up in the next week or two.
Looks like even with the extra 1/2" the tires will tuck into the fenders just fine, especially once we get some good camber dialed in.

Kenny_McCormic wrote: I went and checked the rules, for some reason I was under the impression there would be different min thickness requirements for DOM vs chromoly like in NHRA.

Very good point - I should have thought to mention that. Many sanctioning bodies do reduce the diameter/thickness requirement for bars made with chromoly. Chumpcar does not, so there isn't any associated weight savings, though there is some increase in strength.

So, that's more-or-less got things up to date. I'll get some pictures of the cooling fan, seat and seat mounts when I get a chance, as well as some pictures of the new pars (fire system, LED spotlights, tires, etc). I'm hoping to finish up the roll cage in the next week or two, then it's on to the engine refresh.

We've got a track testing day scheduled for January 11th at Little Talladega so I'll be working hard over the weekends to get everything finished up.

Any plans for the suspension?

Very nice! Makes me want to get moving on my project... But I need to find it in the garage first...

Just as a reminder (that I hate!)...

Wheel spacers cost you $5.00 per wheel for your TCV. I might not use the rear ones if you can get away with it.

Rob R.

Caleb wrote: Any plans for the suspension?

Cut down the springs, check the condition of the ball joints/bushings, get a good alignment (car has double a-arm front, multi-link rear with camber/caster eccentric bolts like a miata).

After the first race, I'll probably get new OE-type shocks. Otherwise, there's not much I can do without accruing loads of penalty laps.

EDIT: Oh, and also possibly a rear sway bar if we need to dial out some understeer, though that would really max out our TCV I think.

wvumtnbkr wrote: Just as a reminder (that I hate!)... Wheel spacers cost you $5.00 per wheel for your TCV. I might not use the rear ones if you can get away with it. Rob R.

Yeah. I've been planning on taking that hit. Rears are certainly optional, but I'm going to make up some spacers for all corners anyway and see if it's worth having them.

I agree with you though, it's a funky rule that really only penalizes teams that can't go out and spend a ton of money on wheels with the exact dimensions that they want.

I'll say, SpeedyCop's SC300 was pretty quick at LeMons Summit Point last year...

In reply to irish44j:

I didn't realize that speedycop had built one of these - it's an SC400 I think after checking the speedycop website.

Where do you source liquid nitrogen from? Great build, very interesting.

JohnyHachi6 wrote:

wvumtnbkr wrote: Just as a reminder (that I hate!)... Wheel spacers cost you $5.00 per wheel for your TCV. I might not use the rear ones if you can get away with it. Rob R.

Yeah. I've been planning on taking that hit. Rears are certainly optional, but I'm going to make up some spacers for all corners anyway and see if it's worth having them. I agree with you though, it's a funky rule that really only penalizes teams that can't go out and spend a ton of money on wheels with the exact dimensions that they want.

Are they still wheel spacers if you epoxy them to the wheel?

Cody_D wrote: Where do you source liquid nitrogen from? Great build, very interesting.

Thanks!

I'm a PhD engineering student at Georgia Tech and work as a research assistant, so I have some friends in the fundamental sciences with access to liquid N2. Classic "sciencey" stuff huh?

Kenny_McCormic wrote: Are they still wheel spacers if you epoxy them to the wheel?

Someone actually asked about welding them to the wheels on the ChumpCar forum. The powers that be said that it would still count if they found them....

Stock Supra TT shocks and springs are a decent upgrade for an sc300.

Stock sc F-357 R-182

Supra TT F-430 R-219

Whatever shape the build is in, bring the car to the car show the first week in April! If you can score a reasonably priced fuel cell - moving that to the trunk and lower will help with front to rear and CG...

JohnyHachi6 wrote: In reply to irish44j: I didn't realize that speedycop had built one of these - it's an SC400 I think after checking the speedycop website.

that would explain why it kept walking me down the straight. I don't think it lasted the whole race, though. But it looked surprisingly in good shape. Hard to believe they got it for under $500.....

MichaelYount wrote: Whatever shape the build is in, bring the car to the car show the first week in April! If you can score a reasonably priced fuel cell - moving that to the trunk and lower will help with front to rear and CG...

I hope to do both those things. Fuel cell is probably not in the cards for a season or two though.

irish44j wrote:

JohnyHachi6 wrote: In reply to irish44j: I didn't realize that speedycop had built one of these - it's an SC400 I think after checking the speedycop website.

that would explain why it kept walking me down the straight. I don't think it lasted the whole race, though. But it looked surprisingly in good shape. Hard to believe they got it for under $500.....

In reply to irish44j:

Yeah. On the speedycop website he said he got it for $400 something with a bad transmission. We have that same V8 in the Wreck Racing miata and it's a solid powerplant and responds well to mild modifications, though we haven't had good luck with supercharging.

Perhaps something to reconsider -- even Lemons/Chump can have some pretty serious 'racing incidents' -- safety should aways come first. If it were me, I wouldn't want to run it hard on the track with that stock tank in it. We want you around to finish that PhD. I'm M.E. '81 from Tech - retired a couple of years ago. So now I can sit around and tell you how to be safe....LOL.

In reply to JohnyHachi6:

I've heard you can get that cast look with some 80 grit and a dead blow hammer.... Though after watching some American 4cyl FWD compact car rip the hub area out of stock steely at a 1/4 mile oval, on a track requiring street tires(no r comps), IDK if I'd go on a track at any competition level without proper race wheels.

So, I'll be working on the cage again tomorrow and should have some more good updates then. In the mean time, here are some of the new parts going on the car.

New shoes! This is one of the only items (other than safety) that I've spent some substantial money on, mostly because it's very hard to find good used tires that aren't R-comps... Looking forward to trying these out. It's actually the first time I have ever bought new race tires, come to think of it, and maybe only the second time I've ever bought a new set of tires, period. (And this is after owning dozens of cars and racing in various forms since 2005.)

New dual zone, dual trigger, AFFF fire system from Racing Fire Systems - they give a great deal on these to ChumpCar teams - thanks!

The seat mounts I'll be using. I made these on the water-jet for my Miata project, and am stealing them for this project until I can make another set.

Here are the LED spot lights that I'm planning to run for the upcoming race at Road Atlanta. The race ends at 10:00 or 11:00 PM so the last two stints will need lighting. I would run the OE headlights, but I am concerned about the chances of destroying them in any potential contact and prefer the idea of hood-mounted units. These also draw less power and should be somewhat brighter. They did run me a fairly pricey $81.56 for the pair, but that's a deal on LED spotlights with CREE LEDs and I consider it something of a safety item.

FYI, ChumpCar has some very specific rules about lights and LED headlights in particular. I was careful in selecting these to be sure that they would be legal.
Kill switches, $9.88 from ebay. I'll probably run one mounted on the trans tunnel or center console area for the driver and one at the base of the windshield for corner workers to use.
Momo marine steering wheel, 320 mm OD. I love the idea of using a white boat steering wheel. It's very solid in construction and water-proof! $37.82 (ebay).

High-density roll cage padding from SafeRacer.
Engine/transmission seals, water pump, belts, hoses, and maintenance items (from RockAuto and Advance), plus Redline fluids for the cooling system, transmission and differential (from SafeRacer).

In reply to JohnyHachi6:

I'm seriously jealous. I've been wanting to do something similar to this for a long time.

I will definitely keep following.

Good Luck!!