MTM

My S2 suspension is a bit more stiff than stock, so I'm wondering if anyone would be able to recommend a good custom alignment setting (especially camber) for my car. I drive it daily and put on about 300 miles per week. I also like to do autocross and spirited driving in the twisty mountain roads on weekends. I have stock anti-roll bars (26mm front and 16mm rear). I have the stock torsion bars (24mm) in the rear, plus 968 M030 dampers, which are Koni yellows plus 120 lb/in helper springs. In the front, I have double adjustable Cup Konis, which have progressive springs that are rated at 185-410 lb/in.

Right now the alignment is set to the following:

Camber: LF = -0.1, RF = -0.1, LR = 0.1, RR = -1.4
Toe: LF = 0.09, RF = 0.07, LR = 0.16, RR = 0.15
Caster: LF = 2.5, RF = 2.7

I think the alignment shop didn't know how to adjust the rear properly, because neither of the rear camber settings are within the factory specifications (-1.3 to -0.7). But anyway, since I have a lot less body roll than stock, I'm thinking that the front camber of -0.1 is just fine for autocross (other people use like -2.5 degrees, which seems really excessive). I don't know about the rear though. Why is the factory spec centered around -1 for the rear, but centered around 0 degrees for the front? I'm tempted to just go with like -0.1 camber all around. I have a quite a bit less body roll now, so it shouldn't be necessary to have so much negative camber in the rear. I would imagine that it would just result in bad wear on the inner edges of my rear tires, since I drive so many miles on the freeway.

Danno

Here's what I recommend for a compromized street-autocross-canyon alignment:

front
camber: -1.50 degrees
toe: 1/16-1/8" total
caster: 3.5 degrees (about the maximum the caster-blocks allows, also required on 18" TSB)

rear
camber: -1.25 degrees
toe: 1/32-1/16" total


Now if you had camber-plates, you can set up two different configurations easily:

STREET & CANYON-CARVING
front
camber: -1.25 degrees
toe: 1/32-1/16" total
caster: 3.5 degrees

rear
camber: -1.00 degrees
toe: 1/64-1/32" total


AUTOCROSS & TRACK
front
camber: -4.5 degrees
toe: 1/32-1/16" total
caster: 3.5 degrees

rear
camber: -1.00 degrees
toe: 1/64-1/32" total

These two different settings would end up giving you better tyre wear on the street, yet give maximum-performance for autocross; something that's not possible with the 1st single-setting for everything. The difference with the extra camber is simply amazing, beyond words, you have to experience it to believe. The extra grip in front removes ALL traces of understeer and the car just goes around corners 10-15% faster than before, might even be a little tail-happy to get around the cones faster. Then just adjust the camber plate back to street settings and drive home...

MTM

Thanks Danno. It looks like a set of camber plates is the way to go, giving me the best of both worlds.

So -1.25 or -1.5 is about the maximum camber you would want for normal street driving, huh? With my old tires, I had it set to -1.8 and the inner edges were worn pretty badly.

Also, wouldn't it be nearly impossible to adjust the toe so accurately? 1/16" = 0.00001736 degrees! :O

Hmm, what is the reasoning behind so much caster? Doesn't that just make the car more stable when going straight? It should also take more effort to steer, since it has to lift up the car a little bit in order to turn the wheels.

Danno

You're welcome Matt!

Not sure how you're converting inches of toe to degrees, but 1/16" is roughly 8.95 minutes of arc, or about 0.15 degrees, about right on with what you currently have on the car.

"So -1.25 or -1.5 is about the maximum camber you would want for normal street driving, huh? With my old tires, I had it set to -1.8 and the inner edges were worn pretty badly."

Yeah, I wouldn't go over that as any extra tyre-grip just isn't worth the extra inside-wear. Especially compared to a full-race setting of -4.5 degrees (the SpeedvisionGT guys were using -5.5-6.0 degrees!!!). Although edge-wear has more to do with toe settings than camber. You can use -2.0-2.5 degrees camber with 3/32" total toe-in. Here's a good article on DYI home alignments.

"Hmm, what is the reasoning behind so much caster? Doesn't that just make the car more stable when going straight? It should also take more effort to steer, since it has to lift up the car a little bit in order to turn the wheels."

Yeah it does make the car more stable. This was probably the reason Porsche recommended it for upgrading to 18" wheels (along with stiffer caster-blocks). The extra caster helps counteract the dartiness and hunting nature of the shorter and more responsive sidewalls. However, extra caster also has the effect of dialing in more negative camber when you turn the wheel...

luckett

I'm running about -1.7, which does wear the insides, but I switch the tires right<-->left to even the wear. Track driving is a good solution to get more even wear when the insides get too worn.

These cars like lots of negative camber for autocross. It really helps the turn in. An alternative to camber plates is to mark the eccentric bolts and shock body at know camber settings. You can then crank it to max camber (~-3) for the autocross and back it off for street driving.

MTM

Oh sorry, I thought you were saying 1/16th of a second of arc (which is 1/3600 of a degree).

That sounds like a nice economic way to do it, but camber plates would be much more convenient right? Is it possible to adjust the camber plates without jacking up the car?

tconn

Doesn't adjusting camber effect toe settings?
If you were to set the car up for street driving then adjust the camber plates
for more negative camber on the track it would change the toe settings...?

RedlineMan

Hey;

Dan is giving you good stuff here. For my dual use customers - and depending on their aggressiveness - I start around -1.5 all around with stock toe (5/64 total-in) and caster (max'd & even L/R). Front toe even or out really makes them turn in, but rips the tires bad. I'm thinking of going back to 0 or even toe in on my track beast, as I always chord the R/F inner, even with differential camber settings.

With camber plates, if you set toe to slightly in or 0, you will have toe out when you set camber for competition use. If you have the time/$ you can dial through the camber range and see what your toe change is. I've never taken the time myself.