So here is another question for Scott. I'm running Hoosier 225/40R18 fronts & 315/40R19 rears. I have the T&A Penske single adjustables and the car has been lowered 1" in the front and 3/4" in the rear. The alignment has been changed twice, both of which are to Alex's specs that came with the shocks. The first time we used:
Street and overall performance use:
Camber in the front –1.10 deg. + or – 0.10 deg.
Toe in front (positive is toe in) -0.05 deg. Total + or – 0.05 deg.
Camber in the Rear -2.20 deg. + or – 0.10 deg.
Toe in Rear (positive is toe in) 0.12 deg. Total + or 0.025 deg.
I have since changed to:
Track usage & Light Street use
Camber in the front –1.75 deg. + or – 0.10 deg.
Toe in front (positive is toe in) -0.05 deg. Total + or – 0.05 deg.
Camber in the Rear -2.80 deg. + or – 0.10 deg.
Toe in Rear (positive is toe in) 0.12 deg. Total + or 0.025 deg.
Here is the issue, the car is super tight mostly into the corner and through the middle and not quite as bad coming off. When we looked at the tires most all of the wear was on the inside two thirds of the tire. The outer third is making very little contact. I am also getting a lot of body roll. At NOLA we mounted a camera so we could look at the tire to wheel well opening and on hard cornering we were probably getting around 3" of body roll. The Hyperco spring rates are 225 & 300.
This car is tracked as much as driven on the street so tire wear and rut following was never an issue but handling is. The car is at Rich & Denis place and will get a new alignment. So my question is two fold. Do you think that the Track and Light Street Usage specs above have too much negative camber and do you think I should go with a stiffer set of coils? I'd really like to get the car more to the neutral side as it is just way too tight. I could post some video of the tire/wheelwell if anyone is interested while I was chasing Rocketman in Stormcat's car.
Hi Art,
Understood on adjustments and tight on entry and mid and better balance off. You note a lot of roll, yet not using the outside 1/3 of the tire.
Based on your comments and our experience in development I believe you are over cambered for the tire and car at your latest settings, but hard to judge. As far as things you can adjust, the tires themselves, including tire sizing/widths and camber will heavily dominate cornering grip and balance, but also heavily affects straight line. More camber hurts straight line braking and acceleration. Typically corner entry tight is not an issue for normal late apex driving and turn with trail braking. The heavy front camber and lack of overall tire usage is likely hurting both braking and cornering. The better balance on exit is likely because of too much camber taking away rear combined cornering and accelerating grip.
Unless it is a typo, I would go to the 245 wide front Hoosiers noted by Black ICE and GulfGT to reduce the front to rear tire split a hair.
Camber - stock cambers are -0.5 front and -1.6 deg rear. So 1.1 deg more at the back...you have the stock camber split.
Need to talk in detail about the current setup and what happens when on the track... If possible, use a tire pyrometer, (not infrared) to check temps for camber and pressure. Should be hottest on inside third, then 10-20 deg cooler mid third and another 10-20 deg cooler outer third.
Toe- I would stay stock and run 0 deg toe at the front. More rear toe- in helps with power down…I think our stock toe was 0.24 deg in total
(I double checked, this is correct). I would look at rear toe of this level. If you get through the entry and middle better you will have a much better run at exit (typically straighter) and likely need/want more rear powerdown.
Your only real tool for stiffening roll are the springs until one of us goes after adjustable bars. I have to do a little analysis to give you a good recommendation for springs. But reducing roll, will make reducing camber more important.
Scott
