OK, I just installed coilovers on my 2G FWD. I took it to get the toe aligned and the camber measured. Here are my camber measurements:

corner actual spec
front driver -1.6 -.8 to +.2
front pass -1.7
rear driver -2.4 -2.2 to -1.2
rear pass -2.2

So I think I'm going to get a Specialty Products kit for the front. The one that will do +/- 1 deg will get me back into spec but on the more negative side, which is what I want.

The rear is pretty damn close to spec, and I'd probably be fine without it (tire wear-wise). BUT, I don't want that much negative camber in the rear because it will cause less oversteer because of better lateral traction as the tread is flatter on the ground under side load. I autocross and want to try and get the car neutral. I think it will be easier with a little less negative camber in the rear. Although I do plan on getting stiffer sway bars soon. Plus I have adjustable shocks, so I can stiffen up the rear more and tune the suspension some that way.

Anyway, my question is, roughly how many degrees of rear camber change will I get with X" of spacers. I want to try and get it as close as I can before I take the car to get aligned again. I think I want to shoot for around -1.5 deg.

If you really plan on autoXing this car then use SP eccentric upper A-arm bushings to ADD more front negative camber. Then shim the rears down a tad to get the car to rotate.

You want 2.5 or more front negative camber for autoXing. If you keep front toe at zero, your tires will be fine. A little wear on insides during the week, cancelled by wear on the outsides on Sunday.

- Jtoby

Oops. I did that obnoxious thing where you go off on a tangent and not actually answer the question.

The vertical link in the rear is about 24" long. So, to do the trig, you first decide how much camber you want to take out (in degrees), find the tangent of this value, then multiply by 24" and that how thick the washers need to be.

Example: you want to take out .25 degrees.

tan .25 = .00436

.00436 x 24" = .105"

So you want about a tenth of an inch in shims or washers behind the upper arm mounts to delete .25 degrees of neg camber.

- Jtoby

Cool, thanks. I thought about doing the math, but I don't understand the suspension geometry well enough to even know where to make the measurements.

I'm thinking about just leaving the front now, but I certainly don't want to add any more negative camber in the front for the street. This is a street car 99% of the time, and I'm only willing to make so much of a compromise on the tire wear.

Could I add a kit to the front and have the alignment shop make marks on it such that I could adjust it myself back and forth just for autocross? Will I be screwing up my toe everytime I do that?

Yes, toe is affected when you effectively change the lengths of the upper control arms. So you have to think this out slowly.

Where is the steering knuckle on a 2G ... it's behind the axis. So, when you pull the tops of the wheels in, dialing in more neg camber for an autoX, what happens to toe ... it toes in. Bummer.

This is why you don't see 2G DSMs dialing camber in and out for an autoX. Sure, things like SP eccentric bushings allow you to do it pretty easily, but this also toes the car in, when you actually want to add toe out for autoXing.

This is one of the only nice things I can say about WRXs (which I hate, because I love them, but I'm committed to DSMs, which I hate, too): because the steering knuckle is in front of the steering axis, when you slam the camber plates over to full negative on a WRX, you are also adding in toe out. So it's very easy to swap the car back and forth for autoXing and then the ride home. More camber and toe out, all in one move. I hate them!

- Jtoby

Jtoby - Just wanted to let you know that I used that calculation and my camber came out almost perfect. I was shooting for -1.5 in the rear, and ended up with -1.5 on one side and -1.6 on the other. One thing to note, taking away the negative camber raised the car up about .25". I lowered it back down to where it was (13.5" from the center of the wheel to the fender). If someone used this calculation and they had lowering springs, they would probably add a little more positive camber than they wanted since they're raising the ride height slightly.

Excellent point. Suspension geometry is non-linear. It's not like you can change one thing and have everything else stay the same. One of wildest examples is when you change toe and both caster and camber change (in the front, obviously), all because of the funky twin front lower ball joints. Therefore, the best that anyone without a complete working computer model of the suspension can do is make suggestions on one things at a time and hope that the other changes aren't too large.

I actually have a computer model of the 2G, but it's one I wrote myself (not a good one from a vendor) and it only seems to get me close. I'm also not 100% sure that I measured the car correctly, so the model has input errors, too. I end up doing a lot of tweaking, as well. If you're within a tenth of a degree of target, you're doing better than I.

- Jtoby

If you're within a tenth of a degree of target, you're doing better than I.

Click to expand...

You're the one that measured the vertical link and did the trig. All I did was plug in my numbers, measure some washers, and throw them on.

Originally posted by jim97gst
You're the one that measured the vertical link and did the trig. All I did was plug in my numbers, measure some washers, and throw them on.

Click to expand...

Concerning the question: "... roughly how many degrees of rear camber change will I get with X" of spacers."

I have a 99 Eclipse GST (FWD) and for THAT car the vertical link in the rear is about 20" long. So for 1 degree of change you multiply 20 times the tangent of 1 which is 20 x .01746 = .349".

I verified this by using three .1" washers as spacers and it removed exactly 1 degree of negative camber (of course the toe also then changed).

Perhaps the GSX (replyer's car) is different than the GST (asking question's car).