Suspension and alignment settings for autocross.
05-09-2005, 07:28 PM
#1
Nordschleife Master
Thread Starter
Suspension and alignment settings for autocross.
Some of you may have read my other thread about the suspension stuff i added to my car, i am curious to the best way of tuning it now. I am thinking ahead a bit after getting my car alligned so its driveable again. I wont be doing another autocross until atleast the first week of August, however would like to have a basic idea of what i want to get done to my car the week i get back.
My current suspension setup is as follows,
-Front-
Struts - Koni Yellows
Springs - Hypercoil 200lb
Sway Bar - 24mm (from '86 951)
Notes - Upper strut mounts changed to the KLA units. Front ride height is 25.5 inches from ground to top of fender, and about 14 inches from center of wheel to fender. I plan to raise the ride height in a bit to get it back around 26 inches to avoid damaging the balljoints.
-Rear-
Shocks - Koni yellows
Sway Bar - 18mm
Notes - Torsion bars and ride height are all untouched.
Wheels - 16-inch design 90's
Tires - Yokohama Avid V4 tires, 205/55/16 front and 225/50/16 rear. They still have a bit of life on them, probably enough to last me to the end of the season i think. I will eventually be switching to the Fuzion ZRi, likely running 215/55 front and 225/50 rear again.
Now here comes my barrage of questions...
1. I know there is no such thing as a good autocross / street alignment because both require compromises. But what would be reasonable settings without needing to worry about abnormal tire wear in street driving?
2. I plan to drop the rear when i get back this July as far as the camber eccentric allows me, then adjusting the front ride height to match. Can anyone verify that the ballpark measurement from ground to the front fender for stock ride height is between 26.5 - 27 inches? What should the height from fender to ground / fender to center of wheel be if i want to lower the front .75 inches overall? I really wish i measured what it was before i started changing everything....
I think thats all my questions...
My current suspension setup is as follows,
-Front-
Struts - Koni Yellows
Springs - Hypercoil 200lb
Sway Bar - 24mm (from '86 951)
Notes - Upper strut mounts changed to the KLA units. Front ride height is 25.5 inches from ground to top of fender, and about 14 inches from center of wheel to fender. I plan to raise the ride height in a bit to get it back around 26 inches to avoid damaging the balljoints.
-Rear-
Shocks - Koni yellows
Sway Bar - 18mm
Notes - Torsion bars and ride height are all untouched.
Wheels - 16-inch design 90's
Tires - Yokohama Avid V4 tires, 205/55/16 front and 225/50/16 rear. They still have a bit of life on them, probably enough to last me to the end of the season i think. I will eventually be switching to the Fuzion ZRi, likely running 215/55 front and 225/50 rear again.
Now here comes my barrage of questions...
1. I know there is no such thing as a good autocross / street alignment because both require compromises. But what would be reasonable settings without needing to worry about abnormal tire wear in street driving?
2. I plan to drop the rear when i get back this July as far as the camber eccentric allows me, then adjusting the front ride height to match. Can anyone verify that the ballpark measurement from ground to the front fender for stock ride height is between 26.5 - 27 inches? What should the height from fender to ground / fender to center of wheel be if i want to lower the front .75 inches overall? I really wish i measured what it was before i started changing everything....
I think thats all my questions...
05-09-2005, 10:51 PM
#2
Three Wheelin'
Join Date: Aug 2003
Location: Louisville, Ky/Altanta, GA (Georgia Tech)
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With my koni yellow i went full stiff in the rear and that leaves the adjustability open in the front. This is a purely autocross setup car. It gives quite a bit of oversteer when the front struts are set to a softer setting, and it can be very balanced as i stiffen the front. As far as lowering don't worry, just drop the rear as far as it will go ( its not too far). The front you can fool with, if you are really worried about the front, then get some adjustable spring perches... otherwise, with 200lb springs you really should be jsut fine with that setup and rear sway bar. No need to go any stiffer.
05-09-2005, 11:04 PM
#3
Rennlist Member
If you have the extra money, you'll really appreciate having a 19mm rear sway bar. Combine the 200# front springs, staggered tires, and the 944's inherent understeer, and your car won't want to change direction.
As for the alignment, keep it close to stock. If you want something a bit more aggressive you can add a few degrees of camber and caster. Having a bit of toe out will also make your car more agile, but will decrease your tire life drastically and reduce stability at high speed.
Even though its preferable to have equivalent ride heigth front and rear, remember that higher in the front will increase understeer and higher in rear will increase oversteer.
Finally, a 2nd set of wheels with race tires will be the biggest upgrade possible.
Good luck!
As for the alignment, keep it close to stock. If you want something a bit more aggressive you can add a few degrees of camber and caster. Having a bit of toe out will also make your car more agile, but will decrease your tire life drastically and reduce stability at high speed.
Even though its preferable to have equivalent ride heigth front and rear, remember that higher in the front will increase understeer and higher in rear will increase oversteer.
Finally, a 2nd set of wheels with race tires will be the biggest upgrade possible.
Good luck!
