RichieRichZ06

Just checking to see if anybody has any suggestions for a C6Z Auto X alignment running Hoosier A6's. We also have Pfadt bushings, coil overs and sway bars. I do not feel like I am getting all that I can from the car. It seems to push in corners and I've been fighting it for a year now on the track. Other cars with similar tires feel much better to me and I can drive their cars faster then mine. Tire wear is fairly even, with the outsides wearing very slightly mor ethen the insides. Currently the car is about -2.5 in the front with 1/8" toe out. Rear is -1.5 with zero toe.

Any suggestions? Please

doje

More camber

Try giving the rear 1/8" toe in.

acrace

Where is the push? Does the car turn in nicely and then washes out? Or does the car have a hard time initiating turn in?

RichieRichZ06

Or I could just drive your car.

It does it everywhere. The initial turn in sucks and mid corner grip sucks. I would say that initiating turn in is not as bad as mid corner push.

I might try a smaller (Z51) rear bar and see if that helps. Thoughts ?

TedDBere

If it's pushing mid corner you'll want a bigger rear bar, not a smaller one...fwiw. Or you could soften the front bar.

RichieRichZ06

I tried softening the rear bar, while stiffening the front and it made it better. It was on the stiffest, but I moved it to the softest in the rear while making the front one setting stiffer and it made a difference. That was my reasoning for wanting a softer bar inthe back.

I want it to handle more like a C5

redtopz

Don't you have a big Pfadt comp bar in the front? Drop down to a smaller front bar and you will be happy . Alignment looks fine.

Also I think you are running 295 in front with 345's in back so 315's in front would be a big plus.

JRL

Smaller bar in front, or bigger bar in rear.
A little toe out in rear to help rotation.

John

Bill Dearborn

You may need to slow more for the corner so you can get the turn in started and then use the throttle to move the backend around. Narrower tire in the rear might help. If you are driving on the track as well I wouldn't go to toe out in the rear. Might work well at a low speed event but could be hairy on a road course. Of course you could mark the rear tie rods and adjust toe at the event. One position for track, one position for street and one for autocross. Most toe in for the track, a little for the street and toe out for autocross.

Bill

JiminVirginia

Soften the front shocks. That should help.

TedDBere

I wouldn't toe out the rear of any Corvette unless I wanted to go drifting. Toe out in the rear will make corner exit an exciting experience. The major issue with any vette is getting power down on exit, and toe out will make it worse. IMHO

TedDBere

That will help with corner entry, but not mid corner. Shock adjustments are for transition elements, not steadystate like mid corner.

Often corner entry push is driver induced so in this case I would try to get rid of the mid corner push before I worried about the corner entry. You address mid corner push by adding grip at steadystate to the front, or loosening grip in the rear. Classic rear bar stiffening, softening front bar, adding contact patch to the front (camber to the front, bigger front tires), smaller rear tires, adjust air pressures, etc.

Unless the car is pushing at exit I wouldn't go with smaller rear tires. You want as much grip as possible when you add throttle.

If you stiffenned the front and softenned the rear bars, and your mid corner push got better, I'd suspect there's some driver induced issues going on here because those changes should have made it worse. FWIW. But it is what it is and you have to set up your car so you are comfortable with driving it with your style.

Good luck.

JRL

You're right, soften front/stiffen rear is best, I was talking about a small amount only for the lower speeds of autox, which would loosen the rear a just bit. On a race track, definitely not, the OP was talking about autox.

Rich is in a class where he can change bars/shocks,etc, that would be the place to start.


John

TedDBere

The other trick you can do in autocross is to play with the center of gravity. If you add rake you will loosen the rear and the car will rotate better. This is the opposite of track because you don't have the speeds in autocross that would normally push down the car and make it more stable with the added rake.

J-Rod

I have a semi-related question.

A friend of mine is a very competetive auto-x'er, road racer, etc (SCCA national champion, driving instructor, etc...)... He has had both C5 and C6 Z06's. We were actually having a discussion about the C6, and I asked him about the C6. He gave the C6 very low marks when it came to auto-x. His view was that GM make the car "stiff" but not particulary good handling especially when it caem to things like in auto-x.

He said the car plows badly, and the rear roll was all wrong for the car and it tended to make the car darty when making rapid corrections. He felt that GM used the AH software and braking software crutch the problem instead of improving the car's handling. He also hated the stock shock valving. He basically told me he thought the C6Z was a pig which is why he sold his.


I don't have a C6Z, I have a C5Z. But, I was wondering since the topic sort of brushed on this topic if I could get some feedback on what some of the other C6Z owners think of the C6 and the C6Z when it comes to them as a auto-x or road race platform.

Bill Dearborn

The C5Z is probably a better autocross platform and is a great track car. The C6Z is a fantastic track car. The C5 wheel base is about an inch shorter and that probably helps it handle quick transitions better.

Bill

RichieRichZ06

Thanks for all the suggestions, I really appreciate them.

I was wanting to change things because the issues are not driver induced. I can get in another similarly car and drive it exactly like I do mine with better results. When other people have driven our car, they say it handles like chit and plows bad. I eeked out a first place overall win for year end points last year and I want to do the same for this year.

If I had some of these other peoples car to drive, top time of days would be a given, but I have to work to hard for it in this damn car.

TedDBere

Say high to Chris for me.

As far as autox goes, I think they are all (C5Z, C6Z and C6GS) competitive to a point and I've seen top drivers win with all of them (as long as Matthew is driving one...lol).

The C6Z has "difficult" gearing and seems harder to balance correctly, the C6GS has the front rim width to compete and the "right" gearing for autocross but once shoed is wider than the C5Z. The C5Z in the right hands is still hard to beat (unless your name is Braun, Rhoades, or Salerno). So I'd say they can all get it done on any given day, as will the Elise, GT3, or Viper too.