FD Autox Alignment Specs
 

My FD is getting aligned this week, and I'm looking for alignment spec suggestions.

This FD is not driven on the street, is autox mostly, a hillclimb next year, and a track day or two.

Particulars:

285/30/18 V710's all around.
ST sways front and rear,
Koni yellows with GC setup and 550/450 front/rear.
Single turbo, about 350 RWHP.

No splitter, wing is stock R1. ( aero is a project for the future)

I would start with Pettit's recommendations:

http://www.pettitracing.com/faq/information.htm

Then just adjust based on your needs and a pyrometer. ;)

Well, alignment will depend alot on the rest of the car setup and driver style. My alignment is something like this....

Front
Camber -3.25deg
Caster 5+
Toe 1/8" out

Rear
Camber -2.5deg
Toe 1/4" in

I'm running more tire (315F/335R) and about 1.75x your spring rates. I'd guess my swaybar bias is much different than yours as well, since I have a 1.25" solid front bar (blade adjustable) and a stock rear bar (17mm or so).

With the type of maneuvers and the grip of DOT tires these days, you will get a surprising amount of roll. When I ran less camber I had very poor tire temps. You might not want to get as radical on camber as me, but I'd run at least -2.5 in front and -2.0 in the rear and monitor. My guess is with your projected power level and the 285 rears, you will want to downsize your rear swaybar and/or run alot of toe in (up to 1/2").

All IMO.

-Andy

P.S. Make sure you get a shorter final drive if you autox alot as well, at least the 4.3. For a truly dedicated autox car, I'd go with the 4.77 (not sure where to get that these days).

Correct me if I'm wrong, but the lower the car is the more static camber you'll need. At or near stock height, there is plenty of dynamic camber gain to keep the tires planted in a corner.

In any case, I suggest starting with the Pettit specs and adjusting the toe to your preference. Then go by pyrometer to see if you need to adjust your camber. Whether or not your alignment will end up as extreme as Andy's will depend on many variables.

I appreciate the replies.

Thanks Andy for the suggestions. I may be going back to the stock rear sway bar.

The car is lowered quite a bit, 1.2 degrees of camber won't cut it with 285 V710's.

Got the car aligned, and was shooting for 2.5 in the front if possible.

Strangely enough the left front would easily go past 3 degrees, but they could get only 1.7 on the right front.

Control arms do not appear to be bent, no unusual wrinkles in the frame. It did appear to me that the subframe was shifted just a bit to the left, which might explain it.

The subframe has been dropped 3 times for oil pan issues, so possibly it can shift a bit from side to side before it is tightened?

Going to find out after the autox season is over, as the control arms are all coming off to install Delrin bushings.

Always something...

As you know my alignment specs are very close to Andy's. One thing I can add is I had a similar problem getting the same camber in both front wheels when I was using the stock upper arms. What I found was; it is a combination of adjusting the caster and camber bolts at the same time to find the max of both. For me it made a -.4 difference. With stock arms I was able to squeeze out -2.1 up front on both sides.

Changing caster effects camber and visa versa. It will take several caster sweeps to find the max for both. I’m fortunate that we have the equipment to do our own alignments, getting a shop to put in the effort to get it right can be difficult.

Hope this helps,
Dan

Even though Rotary Performance (rx7.com) doesn't list the 4.77 on thier site, they normally keep one in stock. Worst case is they will order it for you.

Dan

alignment
 

I am guessing that this is a short track setup. What kind of speed will this start feeling jumpy?

It hasn't felt jumpy this weekend, with 1/16 toe out in front, and 1/16 toe in at the rear. As far as speed I would guess about 60mph tops, though I never actually have time to look at the speedometer.