alignment specs

got a bunch of parts on order to rebuild my rear suspension, and i started looking for alignment specs and cant seem to find the info i want. i either find stock specs or full on race only specs. im after, well i guess performance street is the proper term. here is a little info on my car

-85.5 non turbo chassis
-mono balls on the front control arms, trailing arms, polybronze spring plate bearings, solid torsion tube mounts
-200lb front springs, 27mm torsion bars
-bilstein hd strut inserts/shocks
-stock swaybars, 20mm front 14mm rear (this will change later this year)
-225/45zr17 fronts, 255/40zr17 rear

now the spring/torsion bar ratio might throw you off a little, after a bunch of research i had to take an educated guess. much of the info i read pointed 220 lb springs and 26mm or 27mm torsion bars being a good combo. with my swap (ecotec) the front end is light compared to a stock 944 turbo. i havent had my car on the scales, but it should be around 100 lbs lighter. i also have some additional weight in the back (stereo, nothing crazy but likely 50lbs). i already had the 200 lb springs in the front, i had to put lowering springs in when i did the swap to get the front end to come down. thats how i came up with putting 27mm t-bars in.

so anyone have any input on where i should start with alignment specs?

sharkey wrote:got a bunch of parts on order to rebuild my rear suspension, and i started looking for alignment specs and cant seem to find the info i want. i either find stock specs or full on race only specs. im after, well i guess performance street is the proper term. here is a little info on my car

-85.5 non turbo chassis
-mono balls on the front control arms, trailing arms, polybronze spring plate bearings, solid torsion tube mounts
-200lb front springs, 27mm torsion bars
-bilstein hd strut inserts/shocks
-stock swaybars, 20mm front 14mm rear (this will change later this year)
-225/45zr17 fronts, 255/40zr17 rear

now the spring/torsion bar ratio might throw you off a little, after a bunch of research i had to take an educated guess. much of the info i read pointed 220 lb springs and 26mm or 27mm torsion bars being a good combo. with my swap (ecotec) the front end is light compared to a stock 944 turbo. i havent had my car on the scales, but it should be around 100 lbs lighter. i also have some additional weight in the back (stereo, nothing crazy but likely 50lbs). i already had the 200 lb springs in the front, i had to put lowering springs in when i did the swap to get the front end to come down. thats how i came up with putting 27mm t-bars in.

so anyone have any input on where i should start with alignment specs?

On my own personal 944 turbo, I had full adjustable coilovers with torsion bars removed, and the car was lowered about 3".
I used stock caster and toe in the front, with 1 to 1.5 degrees negative camber. On the rear I could only get it down to 2 degrees negative because of how low it was. So I used a little more than stock toe in to help tire wear. This was my daily driver. I put over 100,000 miles on it like this. Handled really well and tire wear was decent.

i forgot i started this thread.

would you have prefered to run less rear camber if you could?

ive done a bunch more digging and found some more info. guys sure like to run a lot of camber on these cars, most are recommending 2-3 degrees on the front, 1.5 to 2.5 on the rear, more for track only cars. im not really opposed to that much on the front, im already around 2.5 degrees and i didnt notice any excessive tire wear. the general consensus with caster seems to be to max it out, usually ends up around 3 to 3.5 degrees. there is a lot of debate on toe, some say run both front and rear at 0, others say to run 1/16" toe-in on the front and rear. some others seemed to like a hair bit of toe out in the rear, although i think thats more of a track only setup.

after sorting through all the info, this is what ive come up with

camber- 2.25 to 2.5 degrees front, 1.5-1.75 rear
toe- 1/16" toe in front and rear
caster- 3 degrees.

i dont want to get too much caster as i have manual steering with a converted power rack (fast ratio), and more caster equals harder steering. i like a little toe-in up front on most vehicles.

any thoughts on that?

sharkey wrote:i forgot i started this thread.

would you have prefered to run less rear camber if you could?

ive done a bunch more digging and found some more info. guys sure like to run a lot of camber on these cars, most are recommending 2-3 degrees on the front, 1.5 to 2.5 on the rear, more for track only cars. im not really opposed to that much on the front, im already around 2.5 degrees and i didnt notice any excessive tire wear. the general consensus with caster seems to be to max it out, usually ends up around 3 to 3.5 degrees. there is a lot of debate on toe, some say run both front and rear at 0, others say to run 1/16" toe-in on the front and rear. some others seemed to like a hair bit of toe out in the rear, although i think thats more of a track only setup.

after sorting through all the info, this is what ive come up with

camber- 2.25 to 2.5 degrees front, 1.5-1.75 rear
toe- 1/16" toe in front and rear
caster- 3 degrees.

i dont want to get too much caster as i have manual steering with a converted power rack (fast ratio), and more caster equals harder steering. i like a little toe-in up front on most vehicles.

any thoughts on that?

Since my car was a daily driver, I would have prefered less rear camber. Rear tires wore out on the inside edge too fast for my liking. I was driving about 60 miles a day, and replacing rear tires every 4-5 months. If I raised the car up about an inch the camber dropped to about 1 degree negative. But, it looked it better lowered to the ground.

If you aren't tracking your car, I would say get it as close to factory specs as possible. I always ran stock caster settings.

From my understanding of the front suspension geometry, there's not really much lowering you can do without putting the front ball joints under stress and causing early ball joint socket sloppiness.

I've done 2 RennBay track rated ball joint replacements on the original cast aluminum A-arms, only to have them get unacceptably lose after 2 seasons, so much so that I put in Racer's Edge steel A-arms that had a spherical for the ball joint.  Since then, not a problem, regardless of cornering Gs on the track.

eohrnberger wrote:From my understanding of the front suspension geometry, there's not really much lowering you can do without putting the front ball joints under stress and causing early ball joint socket sloppiness.

I've done 2 RennBay track rated ball joint replacements on the original cast aluminum A-arms, only to have them get unacceptably lose after 2 seasons, so much so that I put in Racer's Edge steel A-arms that had a spherical for the ball joint.  Since then, not a problem, regardless of cornering Gs on the track.

My car was lowered 3 inches. I had stock tie rods and control arms on it the whole time I owned the car. Never had a problem. Drove it daily and did a few track days. The guy i sold it to, tracked it a lot also. Maybe the difference is, that I had replaced the control arms, when I first bought the car, with new ones from Porsche. Might be a quality of ball joint difference.

Hotrodz of Dallas wrote:

eohrnberger wrote:From my understanding of the front suspension geometry, there's not really much lowering you can do without putting the front ball joints under stress and causing early ball joint socket sloppiness.

I've done 2 RennBay track rated ball joint replacements on the original cast aluminum A-arms, only to have them get unacceptably lose after 2 seasons, so much so that I put in Racer's Edge steel A-arms that had a spherical for the ball joint.  Since then, not a problem, regardless of cornering Gs on the track.

My car was lowered 3 inches. I had stock tie rods and control arms on it the whole time I owned the car. Never had a problem. Drove it daily and did a few track days. The guy i sold it to, tracked it a lot also. Maybe the difference is, that I had replaced the control arms, when I first bought the car, with new ones from Porsche. Might be a quality of ball joint difference.

Might be. I've been running the after market A-arms for 2 seasons, and so far its gone well, no wear or looseness worth mentioning.

i finally got the alignment done last week. ended up going not quite as aggressive as i was first thinking.

front
camber -1.5*
caster 2.9*
toe 0.08* in each side (0.16* toe in total)

rear
camber -1.2*
toe 0.04* in per side (0.08* toe in total)

i was going to have them max the caster out but decided against it as im running manual steering with a fast ratio rack (power rack thats been depowered). also decided against more camber as i likely wont get the car onto a track this year.

car handles great now. its very precise and stable. took the car for a burn through a back mountain road tonight and im very happy with it. the only thing i now need to work on suspension wise is swaybars as body roll is excessive.