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Anyone Autocross your ZR1?

D

Danger Zone

Guest
I just started autocrossing my '91 and I'm looking for others who may be able to help with some gotcha's. I'm still running street GSC's, what pressures work best? Has anyone run Kumho tires for ZR1 autocrossing? I'm about to install some new Hawk brake pads, any feelings about their Black pads? Lot's of others to talk about... Thanks for your help.
-Mark
 

zr1

New member
Joined
Sep 17, 2001
Messages
1
Location
Smyrna, GA
Corvette
1991 ZR-1
Mark,

I have autocrossed my 91 ZR-1 in the past with some success but don't have experience with street Goodyears. My guess would be to increase pressures by 8-10 psi over the factory spec.

For Kumho's current V700 tire, I suggest that you run 40-45 psi in the front and 5 psi less (35-40) in the rear. For Hoosier's autocross compound radial, I suggest 45-50 psi in the front and 40-45 in the rear.

Your suspension settings will have an impact on tire pressure. My car has a larger front bar (30mm) and koni sport shocks. The front camber is maxed out at ~1 degree negative with 1/8 degree toe out. The rear camber is ~1.5 degree negative with 1/8 degree toe in. Hope this helps.

Steve
 
D

Danger Zone

Guest
Thanks

I haven't measured my suspension yet but I've heard the same numbers from other C4 autocrossers so it sounds good.

On the tire pressures, I had a real problem when I went above 36 in the front or 38 in the back. It was like driving on ice. I've been running about 35F/37R just to keep it pointed straight.

My times are still about 10% behind other C4s with racing DOTs. Maybe the solution is just to go to the Kumho's for the new season.

Has anyone run 315s in the front as well? Anything to watch out for?
 

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