Autocross Alignment and Tire Pressures

[TimeForACobra]

Autocrossing my 2009 BDR #785 with Hoosier A6's, 315/35/17 in rear, 235/40/17 in the front.

Is anyone willing to share their alignment specs and tire pressures?

Thanks...

[vatdevil]

285/315 Nitto NT01s. -1 deg Camber. Low 30s pressure. Just learning, so not too aggressive yet on the camber.

[Cobra #3170]

-3.2 Deg front camber, toe is dependent on geometry, if you have decent Akerman toe in about .030 total front if not you may need toe out.
Air pressure about 28 cold 30 hot. Caster will depend on what your suspension has and may not be adjustable but at least 5 D.


-2.8 Deg. Rear Camber toe in about .060, air pressure 26 PSI cold 28 hot

This assumes that your springs and sway bars are in the ball park, if not, you may have to do some "tuning" If the car oversteers you can go up in rear toe
To as much as .25 total if it understeers you can take some rear toe out down to o" and if you are really quick with your hands you can even put a touch of toe out in the rear (not generally advisable if you aren't an experienced shoe.

This assumes you need to make a quick adjustment at the event, the right way to achieve balance would be through spring and sway bar changes.

Toe should be in degrees but this assumes you are using alinement strings and are measuring to the rim at the center of the tire, it will work.

There are many more parameters including shocks and suspension geometry
but I think Backdrafts are pretty good in the geometry department and shocks don't come in to play until you are fairly experienced and can recognize transitional response problems.
Front to rear rake can effect handling too but it also depends on your roll center heights etc for a Backdraft so I would set that to their specification.
This is also a tunable area but I do not know Backdrafts so cannot offer advice here.

Don't laugh at the camber specs A6's like lots of camber. I run more than that on my Ford GT and it has proper camber gain in the geometry.