Z06Vette.com - Corvette Z06 Forum - Help with Hoosier DOT Radial / Alignment setup

Redshift · 09-28-2003, 11:52 PM

Just picked up a slightly used set of 275 (front) and 305 (rear) Hoosier DOT radials from a great place down in SC for $300 shipped and I suspect that my current -1.8 deg. of camber up front and -1.4 in back won't cut it with these tires. I think they need much more negative camber. I think I can probably get the front to go -2.0 or maybe -2.2 with the stock bolts, and the rear maybe to -1.6 or so, but I don't think they'll go much further.

What do you guys running Hoosiers do about this? Any other tips to hopefully make these last more than 1 or 2 weekends? Here are some pictures of them - the rears are huge!

http://www.pfyc.com/z06/hoosiers.jpg
http://www.pfyc.com/z06/305hoosier.jpg

Thanks.

DJWorm · 10-03-2003, 03:41 AM

Basically the Hoosiers like a lot of negative camber, they work better and have a better (closer) temperature spread with more negative camber.

For AutoX:
Front:
Camber = -2.4 degrees
Caster = as much positive as you can get (always)
Toe = Neutral to 1/8" Toe OUT each, 0 to 1/4" Toe OUT Total Max

Rear:
Camber = -1.5 degrees
Toe= 1/8" to 1/4" Toe IN each, 1/4" to 1/2" To IN Total Max.

For the track (high speed) we can drop the negative camber in the front down to -1.8 to -2.0 degrees and not as much Toe OUT say neutral to 1/16 toe OUT each

We can back off the rear Toe IN to 1/8" each.
We leave the Rear negative camber at -1.5 degrees

If you still have mid corner understeer (and you will) You can move those 305/30x18's to the front. They will bolt right on. You may need to adjust the ride height for clearance if you are lowered all the way. We had to raise 4mm from running the 275x17's. Then get new 12x17"rims and put 317/35x17 on the rear. We had to add a 1/8" spacer in the rear with these wheels CCW's) as the end of the rear spring was making contact with the rim inner lip on hard compression)

What this does is equalize the front/rear contact patch area. It reduces the understeer and makes the car more neutral. It also aids initial turn in and front grip.

The shorter sidewall due to the lower aspect ratio in the front makes response of the tire more stable and allows better feedback and feel at the steering wheel.

The higher (35) aspect ratio in the rear allows the car to squat better which aids traction under acceleration and hiher corner exit speeds.

The difference with the Hoosiers is amazing and the combination with the 305's in the front is almost as impressive.

You will also use higher intitial pressures in the Hoosiers
40 front and 36 rear is a good starting point. We some times go as high as 44/40 and as low as 36/32. We bleed of the excess pressure between runs and as the tires heat up.

Checking tire temps and getting down to a 10-20 degree maximum spread will help you tune the alignment settings to your car and driving style (insides will always be hotter).

Also make sure these tires are warmed up properly.

Redshift · 10-03-2003, 08:11 AM

Sounds excellent. I've already got -1.8 dialed in up front and -1.4 in back. Can I leave that alone and try the Hoosiers?

Thanks DJ, that is exactly what I am looking for.

LtMash1A · 10-03-2003, 07:26 PM

You might want to go to the Tire Rack Web Site and read the skinny on Hoosiers. They recommend 3 degrees neg. camber which you are not going to get and probably is not needed on a Corvette. You will know very quickly if you do not have enough neg. camber because you will see the wear on the outside edge. The site also contains good info on heat cycling and pressure recomendations.
Dave

David Pintaric · 10-03-2003, 07:45 PM

With Hoosiers: negative camber, negative camber, negative camber.

I ran Goodyears this year, and they don't like as much negative camber. But I hear, and plan on finding out next year, that the Hoosiers thrive on it. Don't be afraid of -3.0 if you can get there.

Subdriver · 10-03-2003, 09:21 PM

Brian,
-1.8 front, -1.4 rear will be fine. You will get better performance with more negative camber up front, but it will still be impressive with -1.8.
I'm not sure you can get too much more than that with the stock camber plates, but as DJ said, more is better.
The best way to evaluate your camber setting is to take tire temps immediately after a hot lap. Even temps across the inner third, middle third, and outer third of the tire is ideal. With not enough negative camber, your outer third is likely going to be hotter than your inner third on the outside tires.
Temps of 180-200ish are good.
Have fun!

DJWorm · 10-04-2003, 10:43 AM

You can get up to - 2.4 to -2.5 in the front on a maximally lowered Z06

To get moe you will need the T1 camber kit(s) however some come with the wrong bolt (too short).

In addition the camber eccentrics on the C5 have been known to move.

Hardbar makes a new camber plate kit that is better than the T1 kit and locks the settings. Their kit will get you -1.8 or they can custom make you one to go further.
www.hardbar.net

You may also induce more bump steer and toe steer. There are hemi-jointed rod ends you can get to relieve this problem.

Redshift · 10-04-2003, 11:51 AM

Gary said he would send me a camber kit several weeks ago. He may be still working on it - I dunno. Hopefully it arrives before the November event