alignment specs for autocross
Anyone have some proven alignment specs they would like to share with me for my '00 sedan with 2" lower than stock sport springs(200frt.180rear), with 215/30/18" General UHP's on stock offset 18x8" wheels,H&R sway bars,KYB's.I'm bringing it for an alignment this week (just put in correctional camber bolts in the rear) There is an upcoming Autocross event on a 1.6 mile course I am entering.I did a search for specs,but did not find much.Thanks!
This will depend on your experience level and the speed of the course you will be racing on. Please describe both of them to us.
This is my third autocross,so I am a novice.The track is 1.6 miles long and I am in 2nd. gear most of the time,third on long slaloms.Speeds up to 70mph.
That sounds like a fairly open course, tune for mild neautral understeer? Sideways around a cone at 70mph might not be too cool. Carrera?
What is adjustable in your setup?
Camber (F / R)
I would go with a nuetral to slightly understeery balance on a course like that. You want to be certain that any rear-end rotation that you get it by design, and doesn't just creep up on you out of nowhere. Keep your tire PSIs within about 3-6 pounds of each other, depending on how everything else is setup.
Thanks,I was looking for toe in and camber numbers for the frt. and rear.I used a different car for the other events and this will be my Foci's first cone encounter.
Well, I'm not the most qualified person on here to hand out advise, but here's my thoughts. The H&R sway kit is 24mm front and rear I believe, which should affect your ride similar to my SVT stock setup at 21mm f/r, that being, tending to be pretty neautral. Difference is you'll roll less. Now your springs are biased stiffer towards the front, where SVT stock is biased towards the rear. With even tire pressures and OEM camber and toe specs (which SHOULD be pretty much 0* toe, slight negative front camber and around -1.5* rear camber, but I could be off) the SVT is pretty neautral with tendencies towards mild snap oversteer.
Your front suspension is comparativly stiffer, which will tend to add push, or understeer, to the ride, which will be amplified by the application of throttle. Conventional wisdom is that as a track progresses from
[Technical] -------> [High speed]
your suspension tuning goes from
[Oversteer] ------> [Understeer]
Because going sideways at the top of 4th = bad, but pushing the front end in a low speed corner is no good either.
This is all academic, I dont have a racing career to back any of this up, but I think its pretty solid so far.
What I'd do is keep your toe as close to 0* as you can. Maybe a slight rear toe out. Remember our multilink rear suspension has a passive toe-out under compression. You have a little understeer to tune out, but you can fine tune that with the KYB AGX's adjustable damping. Bring the rear camber as close to true as you can, lowered that car that should be around, what, -2*, -1.5*, something like that. I've seen setups before that aim for -0.5* front/-1.5* rear camber, which makes sense to me. Then I'd bias the suspension damping stiffer at the rear to help maintain front grip.
That should at least give you somewhere to start. If you end up needing less understeer later, rear toe is adjustable as I recall, or you could go back to your stock front sway bar.
Anybody want to back me up/tell me off? Second opinions = for the win.
EDIT'ed a few times for typos.
EDIT: I assumed you had AGX's, the adjustable damping will be good to fine tune w/o going back for a new alignment. Barring that, change your relative tire pressures can help move the handling balance fore or aft slightly if need be. Info found on this page may or may not be new to you, if it isnt, please to not take offense. General suspension tuning wisdom: Linky
Yes,AGX's all around.Currently the car has a touch of oversteer with the back end wanting to come around on hard turns.But controllable.I have the camber at 0 in the rear now (handheld guage)but I am off to the alignment shop friday and will give them the numbers to set the car up to.Thanks for all the imput.Most alignment shops around here don't no anything about setting up a Focus for performance handling.
Front - Full Stiff
Rears - 50%-80% Stiff
Front - 1 degree negative
Rear - 0 / .5 degree negative
Front - 1/16 - 1/8 toe out
Rear - 0 Toe
Front - Max Grip for your tires (measured with pyrometer or shoe polish)
Rear - 4 PSI less than front
Use your rear PSI to fine-tune the setup. If there's something that feels just a bit off, add or subtract a couple pounds in the rear as needed. Most of it's actually finding the most neutral place that you can and then adjusting your driving style to maximize it.
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