steve40th

Being a Novice, I am still just learning how to drive my C4. So far my tires are my limiting factor. But, my tires aren't rolling over, they are right on the edge of the tread block, according to my chalk I left on there.
But, to autocross you need a special alignment to handle quick turning etc, correct. And quick breaking.
And with road racing, you need a good stiff suspension but not to aggressive alignment as you need to have rubber flat on the ground on long straights etc, as you don't want to have too much camber and be riding on the edge of your tire, IMHO.
So, what can you do to really improve in autocross. Camber Camber Camber? Toe it out in front and toe in in the back? I don't know.
But if your tires are horrible, wheres the benefit? What if your springs are weak, and your shocks are average. What can you do to improve the Vette?

63Corvette

THE guy you want to connect with is RAftRAcer.

I am no expert on this, my opinion would be to spend your money on (R compound) tires first,and then seat time.

In general, autocross requires quick transitions, while not allowing enough time to properly heat the tires to optimum temperatures, vs road racing requirements for acceleration, braking, and steady state cornering. The first requirements for racing would be....cooling systems for engine, brakes and trans, brake pads, tires, and seat time.
Your results may differ;-)

robvuk

You can put quite a bit of negative camber on a C4 just by pulling out the shim where the A-arm bolts to the frame. Then when you're done racing, you can put it back for the ride home.

ltborg

seat time is definitely the best thing you can do for yourself in terms of general autocross (or performance driving in general) improvement. its good to have a decent amount of experience on street tires before switching to race tires since they have a much narrower window of warning before they loose grip (i switched after a year of autocrossing on the recommendation of fellow racers). 63corvette is right about the compounds/temps too, thats why most guys run hoosier a6 or kumho v710. those tires will usually overheat and blister on a 20 min stint on the track (dependent on how hard you are driving of course).

more to the point, your alignment will be different for road racing and autocrossing. i havent done much in the way of road racing so i could very well be off but ive been autocrossing quite a while and the formula team at tech that i have been on for 2 years has taught me a few things. for autocrossing you will see people run a little more camber than road racing (at least from what i have seen) but going to extreme hurts in autocross just like it would on a road course. your objective in both is to get as much grip out of the tires as possible, which generally happens with the tire perpendicular to the ground for the best contact patch shape.

the big difference is in the two set ups is the toe. most people run toe out in the front in autocross where in a road race you generally want 0ish toe. toe out causes an unstable condition at high speeds which is obviously undesirable at >100mph on a lot of the straights some road courses have. in an autocross you want the car to turn and react as quickly as possible. since toe out helps with turn in (inner wheel is turned more to account for the smaller radius it is traveling around), youll see this a lot in autocrossing. the stability effects are not noticable at low speeds, making it advantagous for autocrossing. ultimately it will boil down to what makes you fast in your car. a "perfectly" set up car that doesnt work with your driving style isnt going to be as fast as a slightly less perfect set up tuned to the course and your driving methods. sorry for rambling on, hope some of that makes sense.
lane

ltborg

i did this when i had my c4 and it works great but you have to watch out, it is specifically prohibited in the rules for as and bsp classes in scca (i ran sm2 anyway, so suspensions were pretty much free).

steve40th

I know C4's generally can only get about 1.2 to 1.4 negative camber with the shims out, I believe. This wouldnt be too much for autocross would it?
As far as toe out, I wouldnt do it, as the car gets driven to the track and back, as I wont be wrenching on it at the track.
Also, my tires are flat now, of course this is just based on photos etc and the shoe polish I put on the edges.
I guess I could get the aggressive track autocross alignment from VB&P, and this would probably allow me to get through turns faster as it would allow the tire to be flatter at higher speeds since more weight will be thrown on it.

Lancer033

1.4 is still very streetable, that's on the low end for autoX, but makes for a good street/track compromise (my C5 is @ -1.5)

astock165

I think alignment is basically free in AS & BSP. I would use 13.8.B and 13.8.E to make the argument. Do you know what section prohibits it? I could be misinterpreting things.

Steve: I've been running a 93 coupe for quite a while now and think you can safely arrange the shims so you max out the camber so it's equal on both sides (you will probably have no shims on one side and then some on the other to make it even). Then you can set 0 toe in the front. This is pretty easily adjustable before an a/x if you like. Then set the rear camber for ½ degree less than in the front (again equal on both sides) with some toe in for the rear.

I run this alignment on the street (I drive to all my events, and all are at least 1 hour away) and have found my tire wear to be pretty good. Even if it isn’t you can have the tires swapped from side to side half way through their life, assuming they’re a symmetric tread.

Hope this helps.

Aardwolf

If your tires are horrible, you need tires!

ltborg

thats about what i ran on my c4 which was my autox car and dd.

as for the rues that prohibit it:
p.238 of the solo2 rules under clarifications of rules - "CONTROL ARM SPACERS - CORVETTE (84+)
The spacers located on the fasteners for the front upper control arms
may not be removed or modified to gain additional camber/caster.
Only the shims may be removed."

cant find it in the sp clarifications so i guess i was wrong on that and it is only a stock class restriction, sorry about that.

technically i mistyped referring to spacers as shims. i pulled out the spacers and most of the shims (some left to get caster correct) to get about -1.5 camber in the front. without pulling those spacers you get stuck at around -.7 or -.8.

AU N EGL

IMHO for the first 10 or so track weekends just use an agressive street set up for camber. Nothing more then that.

and stick with stock street tires for at least 1/2 dozen events to learn the car and handling. R compounds may be the cool and sexy thing that everyone does, but not always the best for novices to learn on.

Track time is the best modification that you can do, more so then bolt ons.

Good Luck and have fun

astock165

That's what got me. I figured that HAD to give you the shims since that's how you would add camber as well. They have to give you something.

I agree on the spacers though.

RX7 KLR

SP rules follow stock unless otherwise listed, if it does not say you can then you cant. You can not touch those spacers in stock or SP, only shims can be removed. If you want to cut them down or pull them out you are looking at SM2.

BrianCunningham

I've been driving my car on the street w/o shims in the front for years. No problems, it's the toe that kills your fronts. I run a lot of toe-out at an autocross, like 1in. On a road course I don't run as much, 0.25in.

At events that don't care about the shims, I've rested the a-arms right up against the frame rails. Great for turn-in and cornering, but it really compromised my braking! So for tight autocross, I do it. I've know people who do it on a road course, but with my 335's up front, it's just too much camber.

Not to get off topic, but what road course are in Hawaii?

UstaB-GS549

I do both. Autocross can use toe-out for turn-in, but it wears out tires quickly. It also makes car nervous at speed. I run toe at close to zero to favor road courses and am not as competitive at parking lot events. Too lazy to change toe setting for every event.

astock165

WOW that seems like too much. I've found that when I run more than 1/4" out in the front it kills the steady state turning, even in a/x. I run 0 @ the track and on the street.

BrianCunningham

I'm used to really constipated lots

At Devens I don't run that much.

If you tape the toe links and count the threads,
You can change the toe relatively fast.
Got to love the clamshell hood!

ltborg

yeah i miss that hood soooo much, alignments were a breeze. not that im complaining about the c5 or anything...

RX7 KLR, good catch. i totally forgot about that. i guess when you get into sm2 and just stop worrying about those things.

AUTO_X_AL

Same here 1/4 out for AX close to 0 for road course.

Al