[CarJunkie]

I get a lot of questions about my chassis setup, and my progressive changes have been discussed in various threads over the years, but I thought I would update where I have ended up, with a setup that I am VERY happy with!

Hardware:
I run Ohlin's R+T coilovers with their springs, lowered about 15mm front and 5mm rear, Vorschlag camber plates set to the lowest caster setting (stock caster, with change resulting only from ride height adjustment), and the M3 convertible front sway bar properly balanced with Turner adjustable links.


Evolution of alignment settings:
On stock staggered setup, I found that a 1 degree difference in camber front to rear produced very neutral cornering balance, with the hardware above and RE71r tires (255/35/19 front, 275/35/19 rear) at autocross and track.

I used a set of RE71r's at -2.7f/-1.7 rear and performance was good, but there was excessive inner tread wear in mixed street and track use. To reduce negative camber wear, I did one season on RE71r's with -2.5f and -1.6r and overall grip suffered. They still wore excessively at the inner edge, so damned if you do, and damned (plus slow) if you don't. I then gave up on trying to find a solution that would compromise tread wear and performance.

In 2018, I mounted PS4S (again 255f/275r) on my stock wheels for the street and to be a backup for rain the track. I accept that they will die early from inner tread wear, but not before I have a chance to heat cycle them a few times on rainy track days. I got a square set of wheels (Apex Arc8 18x9.5et22) for the track.

I settled on -2.8f/-2.2r for overall grip balance. This will presumably understeer at the limit on stock tires (haven't really explored that yet), since with square setup it is perfectly balanced. At the track, the car has sharp immediate turn-in without trail braking, is easily controlled mid corner with a 4 wheel drift at the limit, and no hint of understeer when feeding on throttle at corner exit. I haven't had a chance to run the staggered setup on this alignment at the limit yet.

I believe this alignment is perfect for my driving style. This year I used Toyo T1R's. Once I got hot pressures dialed in, tire temps were perfect across the tread. My tires corded at the inner edge, but the wear was even enough that no change in alignment would have gotten more than another session or two out of them.

My car was driven by an former Porsche professional driver development coach who has literally driven everything, and he said "I don't know what you have done to this car, but it's brilliant. I am in love."


Rubbing:
I have the revised fender liners. I use a 10mm spacer on the front only with my stock wheels, which undoes the excessive top tuck resulting from the aggressive negative camber. With spacer, my stock fronts with RE71r 255/35/19 tires rub at the top under cornering and compression, not enough to worry about. My right front also rubbed on the right only when turning right where there is a bulge behind the wheel on the right wheel well. This bulge is not present on the left where the tolerance is tight, but no rub. The RE71r's are wide and wore down the plastic there on the right side bulge, but not enough to create a hole. The PS4S in same size does not rub there, and probably doesn't rub at all. Who knows if it would rub if the two sets of bridgies hadn't done some clearancing work.

With the track wheels, no spacer on front, big compressions cause a rub on both sides. They don't rub at the rear side fender bulge.

Note that increasing caster even 1 step up on the camber/caster plates would worsen the rubbing on the right side behind the wheel, and probably also produce rubbing in the left. Increasing caster from the top only moves the wheel rearward in the wheel well. There are caster control arms that work from the bottom and you would really need to do both to maximize caster while maintaining clearance for the widest tire possible.

I'm just happy I can fit a 275 all around. The lower diameter helps.

My rears don't rub at all, 275/35/19 on stock wheels with no spacer, or 275/35/18 on track wheels with or without 10mm spacer.


Pictures:
Current alignment (did I mention I love it?)
Side view with OEM wheels (10mm spacer on front only)
Side view with track wheels (10mm spacer on rear only)