auto-x allignment specs

[sho_bc]

figured i'd start a thread where people can post their allignemnts and thoughts/experiences on different set-ups.


based on Fred's post here, i was thinking of going with a street/auto-x set up of the following:
Front:
Camber -2.25 deg
Toe 1/16" toe out

Rear:
Camber -2.25 deg
Toe zero

is it fine that the front and rear camber are the same? or should i have a little less negative camber in the rear? any thoughts on caster angles? i'm at 4.6 and 4.8 degrees on R and L respectively (not sure why they'd be different....)

 

[Shoaz]

Running the same camber front/rear won't hurt anything, and those numbers look pretty good. Keep an eye on your tire wear to make sure things are going the way you want.

Personally, I'd put a tiny bit of toe-in on the rear for stability on the street/highway, but it doesn't need to be much at all. That's just me, though, and zero isn't bad if it's really zero. You might also start with zero toe in the front while you're learning and then move to a little toe-out, especially since this is your street car. FWIW, I still run zero toe in the front and a tiny toe-in in the rear on the Pumpkin, but that's partly because I can play with handling via the springs.

On a SHO generally more caster is better, and it's sometimes hard to get things exactly balanced side to side. If the subframe isn't exactly centered and exactly square with the car, and if the unibody isn't exactly straight and square (and it's rare for any of that to be exactly right), then imbalances will happen when you're trying to get to the limit of the alignment capabilities. I usually back off on things so that they're balanced, e.g., if I can get -2.5 camber on one side and -2.25 on the other, I'll back the -2.5 off to -2.25 so that they're balanced. That's harder to do with caster, and the caster imbalance probably just means that the subframe isn't exactly square with the unibody.

 

[sho_bc]

yah. really, the only time the car gets driven is on its way to/from auto-x and while i'm there. its mostly fairly straight highway driving to get there. I think as soon as i get the new wheels mounted, i'll get the allignment done. switching wheels shouldn't make a different, right?

 

[AutoSHO]

No, wheels won't make a difference with respect to the alignment.

For a really good auto-x setup, I would run toe-out in the rear. But, that's not a particularly useful street alignment, so I would stick with Eric's recommendation of 0-1/16" total toe (in). The car won't be as willing to rotate, but it will also be driveable on the street and on a track if you ever wanted to do that. Autocross is a strange sport with an even stranger tuning philosophy behind it.

 

[sho_bc]

wow, chris is alive and posting!


thanks for the advice. i'll probably keep it at 0 in the back.

 

[AutoSHO]

Once in a while. I saw Mark's 325/328 DSP car in a few of your pics... That thing is neat. I want it.

 

[sho_bc]

you know mark?

he's caging and gutting it soon and going to run prepared. he has said (don't believe him though) that he doesn't care about PAX time anymore, its all about going fast. he actually had it up for sale for a while, too. he was looking for $16500cdn as-is. not sure if that included all the wheels and tire combos as well or not.... for the right amount, you could probably still talk him into selling it.

 

[AutoSHO]

He posts on bimerforums pretty regularly, so I recognized the car when I saw it.

Trust me, when I saw it for sale I thought very seriously about it.. That car is probably 95% of the way to being national champion-level competitive in DSP. I'd love to buy it but I decided to stick with my car mainly because it's been so reliable. I've put over 40k on it in the year and a half I've owned it... and done 16+ autocrosses, 4 track events, several roadtrips... and had to put almost nothing into it. Definitely a different experience after my last SHO. Not to mention, it's a friggen' riot to drive now with the new suspension... I can't wait for springtime!