Fast_Toys

Hi Guys,

I have an 01 C5 Convertible I am running at auto-x. I presently run 4 315/35/17 Hoosier A3S05's. I really need to improve the turn in as the tight sections are killing me.

I still drive this car on the street so I need a good compromise alignment that will be good for auto-x but not cord the street tires. Any recommendations for alignment settings?

Thanks!

Solofast

First, even agressive autocross alignment settings won't be horrible on tire wear if you don't get greedy on front toe out for the street. I have 8,000 miles on my car and you still can't see much of any difference in tire wear inside to out. I am running zero toe on the street. It is toe out that kills tires, so you need to add some toe out at the track to get your turn in, but not have it on the street.

Mark the endlinks and the tie rods to find bottom dead center. Raftracer uses nail polish, but you can use any kind of paint (Danny were did you get that devine pink that you used on my tie rods)....

Then loosen the jam nuts and crank out 1/2 turn on each tie rod when you change to your racing tires, and then crank it back out to go home and set it to your marks. It only takes about two minutes to do it, the alignment will be fine on the street and you can go from zero toe to about 1/8" total toe out with that move and that will help turn in.

If you are using rubber bushings on the front, put two 1/16th of an inch alignment shims, between the swaybar bracket and the frame one for the front bolt and one for the back bolt of the front bar bracket. It will soften the bar preload enough so that you will be able to notice the better turn in.

In the front, max out the negative camber (around 2 degrees) and shoot for 6 or seven degrees of caster and zero toe on the street. More caster is good for turn in, so get all you can.

In the back go for 1.5 degrees of negative camber and about 1/8th of an inch of total toe in.

That will be close, you can adjust from there according to taste....

Fast_Toys

Ok.. so you suggest zero toe front for street driving and 1/8" total toe in for the rear... max out camber at both ends and 6 or 7 degrees of caster at the front?

How do you find your auto-x performance with those settings?

Good ideas on marking the front tie rods... I will have to try that!

Solofast

1. Yup, thattl do er.....

2. Assuming that you crank the toe, you are pretty much there as far as alignment goes. To do any more in stock you are going to have to go with lowering, different shocks and tune the front bar, but for alignment you are pretty much done.

3. Not my original idea, but for a dual purpose car it works fine. I just usually ran 1/16th to 1/8" out on the street on my C4's and pretty much brutalized the front tires in 20,000 miles. Doing this is now pretty much part of the drill, and the car doesn't wander and tramline over every rut in the road, which makes for a more enjoyable street car.

Still, with toe out on the street you will never fall asleep at the wheel

Norm_427

You could also just count the number of "flats" on the tie rod that you are turning. I think there are 6 ... turn it 3 flats OUT on each side and when you're done turn it 3 flats IN.

Norm

yellow01

you can say that again. I have been doing as you said above and running the toe-out on the street also (due to laziness). It is hard on the tires, but it is funny, if I had a dollar for everytime I turned in too far in a left hand turn and had to reel it out again I could afford a few more mods.

Turn-in at street speeds feels like I'm driving my wife's mazda with the 205 tires

tjZ06

Lots of good advice in there, I can't wait to get an aggresive alignment on my Z06. With my Camaro ('99 Z/28) I ran ~ 1/8th total toe out up front (along w/ maxed neg. camber of 1.4 for my car and 4.5 caster) and I did kill tires in 15-20k miles (inside edge of course) but that's not that bad. I have plenty of friends w/ "stock" alignments that kill the outside edge quicker due to the factory positive camber (and non-racers seem to just push their cars harder on the street for some reason).

-TJ

Fast_Toys

Hmmm..well my car is an 01 and has less than 15K miles on it! Maybe a little toe in the front would let the tires still last another 4-5 years!

rhneff

Lots of good general advise from others and I agree with most of it, but would also comment that optimum alignment is heavily dependent on the rest of your setup like shocks, swaybars, etc. You don't mention what clubs/rules you're running under or what mods you have or haven't done and both could change some of the input you'll get.

Assuming you're running mostly stock suspension I'd also note that IMHO part of your issue is the tires. I tried 295's in place of 275's on the front and found a notable reduction in response, so I suspect 315's would have been even worse. The wider tires might (and I stress might) give you more grip in steady-state cornering but they'll definitely cost you in fast transitions (again, assuming stock suspension).

Also, you should dump the S05's and get some A6's (or V710's). That would help a lot .

Fast_Toys

The 315's dumped me into ASP. I basically got a great deal on a used set of AS05's in that size so I thought I would try them

The car has been lowered on the factory bolts, has BMR front and rear sway bars and Bilstein sports all the way around. Other than that, suspension is stock Z51. Race weight approx 3350 lbs with me in it.

The car only sees about 3-5K miles a year in total. Just a sunny day car and auto-x racer.

Any advice based on the above would be appreciated.

Norm_427

Actually, it's not the tire size but wider wheels or a change in wheel diameter that would throw you into SCCA's ASP. Run any size tire you want ... but you've also made a change in rear sway bar that would throw you into a street prepared class.

Norm

Fast_Toys

The tires sticking beyond the fender was the nail in the coffin or I could have stayed in the A Superstock class we run up here