Cal Club Autocross Forums

It was my understanding that the Holy Grail of set-up was to achieve even tire temps across, side to side and front to back ... showing that the each part of the tire and each side and end of the car was sharing the work load evenly.

I know that tire temps should ideally be taken with the car fresh off of a skid pad. Couldn't do that, but I was getting those very even tire temps coming off the course on Saturday. But the Vette, on 710's now, seemed to lack a bit of front end bit. I had reduced front camber to -1.7 to get the tire temps more even. With the Hoosier camber setting of around 2.5 the inside temps with the 710's was as much as 20 degrees hotter then the middle/outside. Front Toe out about 1/8" ... rear toe in about 1/4. Fresh 710's running 34/31. Forgot how crappy first runs are on 710's.

Can tire temps be too even for AX ?

Why would you have put a wrench on that car and changed a thing?

It was set up for Hoosiers on concrete or El Toro. Bryan drove it at CA Spdwy when he delivered the car and felt it had too much understeer for the less grippy spdwy surface, let alone 710's. Also it didn't like the bumps being as low as it was. I've been working with Bryan on the changes that we've been making.

I know you are the Guru of setting up a car and leaving it alone ... and just learning to drive it. Me, I think all of those nuts and bolts are there for a reason. =

Mako Koiwai wrote:
I know you are the Guru of setting up a car and leaving it alone ... and just learning to drive it. Me, I think all of those nuts and bolts are there for a reason. =

And what are the chances you have made it better than it was. Slim, or none?

OK ... so are you willing to comment on my original questions on camber and tire temps?

I DO get a lot of satisfaction working on the car. I don't mind futzing with the alignment until it's just where I want it ... not that that might be correct.

Mako Koiwai wrote:OK ... so are you willing to comment on my original questions on camber and tire temps?

I DO get a lot of satisfaction working on the car. I don't mind futzing with the alignment until it's just where I want it ... not that that might be correct.

Yes, put the camber back in and drop the pressures, and/or soften the front bar. I can't think of any stock class car that would not benefit from -2.5 or more camber. If you wanted to run -1 you should have bought a C4.

Thanks ... I was surprised to hear that the Lynches run as low as 28/24 with their 710's ... and The Tire Rack recommendations for the 710's is less then one would think. I did drop the pressures to 32/29 on Sunday ...

Post-lap temperatures are helpful, but lap times and how the car feels and responds are the first priorities.

IMO post lap tire temps are worthless. it will always show temps that are inside hot because you have negative camber and the last element you perform on course is hard braking. so unless you're maximizing braking alignment you're wasting time. Any amount of toe will also make the inside edges read hot.

Tire wear is a much better post lap indicator of tire use. On the kumho's get the camber so that it doesn't use the outside 1/2" or so of the tire and you're about right for the front tires (hint: don't use the part that's all rounded off). adjust the rears to balance/put power down, they'll be more straight up than the fronts.

I know you're not using 315/335's on the SS car but for reference the ASP car ran 28f/24r pressures on the Ktires. pressures should be a little higher with skinnier tires.

I'll refine Marshall's comments slightly by pointing out that toe-out will heat the inside edge, and toe-in will heat the outside edge. Every properly setup car I have taken temps on showed mildly higher temperature on the inside of the fronts, mostly because of braking. Keep in mind this is for cars that can get enough negative camber (like yours), where most stock class cars cannot. The SS Z06 needs at least -2 degrees front with 710s in my experience, and many people run more than that with good results.

Front pressures are a compromise between feel (response), temps, and lap time. Quite often, the settings that feel best are not the fastest. IMO, lap time easily wins this argument. This car's strong point is its power, so the rear pressure and camber has to be set with this in mind.

You say you like to fiddle and experiment, but you have to consider the fact that the C5 Z06 is a well-known device where the setup recipe is easy to find by asking around. Any experimentation from there may be entertaining, but will just cost you races. Up to you.

Not a (intentional) hi-jack. As long as we're talking set-up with a C5 - I think my setup needs some help and unlike the Z06, to some degree I'm in uncharted territory. My hardtop has '04 Z06 shocks, Z51 (stock) front bar, front tires are 275-40/17 on 8.5 wheels, rears are 285-30/18 on 9.5 wheels. 1.6 neg camber front, 1.3 neg rear. zero toe front, 1/4 rear toe in.

On both days this weekend I could not get the back of the car to hook up. Much looser than with taller. wider rear tires. Folks have said that I should get better accel out of slow corners, but because of the increase in "dirt tracking" I couldn't tell for sure.

Suggestions?

Marshall Grice wrote:IMO post lap tire temps are worthless. it will always show temps that are inside hot because you have negative camber and the last element you perform on course is hard braking.

Good point: with the Corvette you're braking much harder in the shut-down than you ever did in the Miata.

Go with more rear toe-in (per Tom B. etc) ... I'll PM you on doing it yourself at the track. Very easy ...

Steve Towers wrote:Not a (intentional) hi-jack. As long as we're talking set-up with a C5 - I think my setup needs some help and unlike the Z06, to some degree I'm in uncharted territory. My hardtop has '04 Z06 shocks, Z51 (stock) front bar, front tires are 275-40/17 on 8.5 wheels, rears are 285-30/18 on 9.5 wheels. 1.6 neg camber front, 1.3 neg rear. zero toe front, 1/4 rear toe in.

On both days this weekend I could not get the back of the car to hook up. Much looser than with taller. wider rear tires. Folks have said that I should get better accel out of slow corners, but because of the increase in "dirt tracking" I couldn't tell for sure.

Suggestions?

That's the trade off of the 285s in the rear - more torque multiplication because of the smaller diameter but also less forward bite due to the lower, stiffer sidewall. I have the same choice on my car to make, and use the 305 at SD and Fontana, and the 285 at El Toro where the extra grip makes the 285's lack of bite less of a problem. Unfortunately they require a slightly different setup to be at their best.
You might try more rear toe (as Mako said), a Z06 front bar, and go lower with the rear pressure. I really don't know of anyone that actually likes the 285 on the back of a Corvette though - I didn't :unimpressed:

You might try more rear toe (as Mako said), a Z06 front bar, and go lower with the rear pressure.

Wouldn't the stiffer front bar make the back looser yet? By the end of the Sunday event I was down to 25 psi rear.

Steve Towers wrote: Wouldn't the stiffer front bar make the back looser yet?

negative, it would do the exact opposite.