Geoffrey

Anyone,

What alignment specs are recommended for a car that has suspension done and is lowered? I use the car 90% street, 10% track.

Thanks in advance

gaijin

Front .7 degrees negative camber. 6.5 degrees caster. Match them as close as you can. And 0 inch tow.

Rear .5 degrees negative caster and a touch of tow in. Less than 1/16 of an inch.

BrianKeithSmith

What about alignment specs for a 930 that is driven 90% of the time on the track and only 10% (or less) on the street.

Also, can the rear of the car be lowered in much the same manner as the front, with the simple turning of a bolt (if so, where is the bolt), or does it require removing the torsion bars and re-positioning them in the housing?

Thanks,

Brian Keith Smith
1983 930
<a href="http://home.carolina.rr.com/logicode" target="_blank">My 930</a>

Geoffrey

Brian,

I ended up with the following alignment spec for a car that is agressively driven on the street and tracked with R compound (Yoko 032Rs) tires:

Front: Toe-in 1/16", 1 1/2 degrees of negative camber, 5.4 degrees of caster (you want as much as your car will allow, within reason)

Rear: Toe-in 1/16", .7 degrees of negative camber. Note, I wanted 1 to 1.2 degrees of negative camber because I'm running 315/35/17 which don't need as much camber as a smaller tire, but was only able to get .7 out of the adjusters.

I don't notice any major tire wear and the car is solid at 150mph track speeds.

With regard to adjusting rear height. If you have the aftermarket adjustable spring plates then you can adjust about 1.5 inches of height with the turn of a screw. The stock parts must be adjusted by realigning the torsion bars which is a fairly straight forward procedure (I did it my first time in about 2 hours for both sides). There is a fine adjustment on the stock setting that has about .75 inches of adjustability, but you need a special flat wrench and it can be a pain.

Also, if you lower the front of your car, you will want to get a bump steer kit. I used the one where the tie rod ends are replaced which made a huge difference but you will notice an increased steering effort. My car sits at 24.5 inches in the front and 25 inches in the rear measured to the highest point of the wheelwell.

ngoldrich

Brian,

Lowering the rear is not as easy unless you have coilovers or adjustable spring plates.

It's been a while since I have done it on a stock car. Mine had coilovers.

But if memory serves, you need to actually loosen the spring plate, pull it off and put it on the next spline then reconnect. Make sure the car is in the air and watch your hands since there can be quite a bit of pressure on the torsion bars. But with the car in the air, the should be unloaded....

A few things to remember when aligning for the track :

(1) Changing the camber also changes the toe so you need to check/set both.

(2) When lowering the front, make sure to keep the geometry correct. You will most likely need to put bump steer spacers on the steering rack.

(3) Be careful how much you lower the rear as you will start binding the CD joints because they will be at an unintended angle. Just dont go too low...

(4) Make sure the front-rear rake is still correct. If memory serves (1 degree, but check because I am not sure).

(5) For the track I always ran 1/8 inch toe out in the front so it would turn in better. And 1/16 toe in in the rear. But again, these are track settings...

(6) On the track I ran -1.3 front camber and -1.1 rear. This was on a 935 with big slicks. But many others ran this same setting with wide R compund track tires.

(7) Corner balance the car.

Hope that helps. Just recalling from memory.

Norm

BrianKeithSmith

I am running Goodyear slicks. 245x17 in front, 275x17 in rear.

Thanks for all the info. The only difference I've noticed is that for the track you guys are recommending some toe-in, but everyone I've talked to at the track says they are running NO toe-in.

Just a difference in opinion I guess.

Thanks,

Brian

BrianKeithSmith

And Geoffrey, where did you get your bump-steer kit?

Brian

ngoldrich

Brian,

Toe 1/8 OUT in the front.

Toe 1/16 IN in the rear....

Norm

PS - Bump Steer spacers you can get from Automotion. I believe they are part of Performance Products now.

ngoldrich

Brian,

BTW - I ran the 1/8 toe out front and 1/16 toe in rear for 6 years on my 935 as well.

I also ran it on my Spice GTP as well as the Lola Can-Am,and 125 Shifter Kart. Works very well with all.

From all the testing we have done over the last 16 years of racing, toe in on the front was not as good as toe out.

But I am no expert.

Everyone seems to setup their cars a little different. So I always try changes and realign at the track. Either string the car or use ART laser alignment - which is what we do...

Document all of your baselines as well as changes. That way you can see how well it suits your specific setup. Just because it worked well on my cars does not mean it will be the best for yours.

Hope that helps.

Norm

Geoffrey

Brian,

Stephen at Imagine Auto and Steve at Rennsport Systems here on the list can sell you the bump steer kit and help you decide about the alignment specs.

The PO of my car had the front with slight toe out and it seemed to work fine on the street, even with a blast to 170. When I was researching alignment specs, 1/2 the people told me to run toe-out saying that the car would be more stable, the other 1/2 said to run a little toe in because it would make the car more stable. I chose to try a little toe-in and see for myself since I already felt the car with toe-out. The car seems great and is very stable. It certainly corners better than its driver can push it at this time... Since I have access to an alignment rack at a friend's shop, I'm going to reset it and try a little toe out. However, I suspect that for the street driven car, a little toe-in will be the best setup since it will tend to "pull" the car straight. I would think that running a little toe-out will help the car corner better, but will probably not be as stable at high straight speeds. I don't know for sure as I'm not an expert. Also, the Up-fixen der Porsche books have quite a few suggestions on alignment settings. The one thing I found was that there seems to be as many opinions as there are people to ask.

PT

I'm running 0 toe in the front & 20 minutes toe in per side in the rear.
Really curious about the advantage of toe out in the front. Would have thought 0 toe would give you most balance for turn in?

Geoffrey

My understanding is as follows: Toe-out will provide you with sharper turn in, but the car will tend to be "darty" in a straight line. Toe-in will tend to pull the car straight, but won't have as sharp a turn-in.