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alignment specs for autocross

4K views 13 replies 4 participants last post by  QQQQ 
#1 ·
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!
 
#2 ·
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.
 
#4 ·
That sounds like a fairly open course, tune for mild neautral understeer? Sideways around a cone at 70mph might not be too cool. Carrera?
 
#5 ·
What is adjustable in your setup?
Camber (F / R)
Shock Damping
Swaybar

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.
 
#7 · (Edited)
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
 
#8 ·
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.
 
#9 ·
My reccomendation;

Dampers;
Front - Full Stiff
Rears - 50%-80% Stiff

Camber;
Front - 1 degree negative
Rear - 0 / .5 degree negative

Toe;
Front - 1/16 - 1/8 toe out
Rear - 0 Toe

PSIs
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.

Good luck!
 
#11 ·
Carrera26 said:

PSIs
Front - Max Grip for your tires (measured with pyrometer or shoe polish)

I don't want to jack your thread, but how do you measure grip with shoe polish?
 
#12 ·
Draw 3 equidistant lines through the tire's "shoulder", from the sidewall to the tread. After your run, you will see how far your tires are rolling over by how much shoe polish is worn away. If it's past the shoulder and onto the sidewall, then your tire is rolling over too much and you need to add air. If it's still present past the shoulder onto the tread then you have too much. If it lines up right where the tread and sidewall meet then you are getting the most traction out of your tire, as it's using the most possible tread in hard corners.
 
#14 ·
Alignment done.Car feels like it's on rails!Much more forgiving with much less steering imput.I am carrying a LOT more speed into corners without the back end wanting to break loose...Can't wait for the 24th!Thanks for all the help!!
 
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