DGC

I'm looking for advice on my alignment issues. Finally decided to take on the slight right pull on my '87 911. Alignment specs were good all way around, so I decided to check wheel weights. Found right front left rear 110 lbs above opposite. Went to the effort to adjust left rear torsion bar down 10 degrees and adjust the torsion bar ride height cam to get back to equal fender heights front and rear,left and right. This corrected corner balance issue. Reset alignment, and still have slight pull to left. But car is corner balanced.... Now I believe the caster adjustment is source of problem. Double checked 20 degree caster settings and I believe the problem is in mismatched cross caster settings. Opened up shock tower mounting plates to increase caster range. This helped a lot to correct left pull.
So, here' my question. Has anyone else been able to improve the cross caster range by enlarging holes in fender where shock plates bolt in? I see that there are after market shock towers, but I do not want to go that route. Other suggestions are welcome.
Thanks,
DGC

Ed Hughes

I don't know where you are getting your specs, but caster should be no where near 20 degrees-in fact I don't think you can adjust that far. I ran about 6 degrees of caster. If you think you are measuring that much caster, my guess is your equipment is out of whack, and you may want to start over.

Tires can cause pull (even brand new ones that are bad), dragging brakes, etc. It isn't always alignment.

DGC

Ed,

Thanks for the comment. The caster angles fall in the 3-6 degree range. The measurement is made with the tires turned 20 degrees right and 20 degrees left. The left and right angles do not matc. The problem is that the adjusment range is not sufficient to make them match.

DGC

Ed Hughes

You could have a bent strut

Droops83

Ed makes a good point about the possibility of a bent strut. That would certainly affect caster and possibly camber settings as well.

How close are you able to get the caster settings as is? In my experience it takes a difference of about a half of a degree from side to side to cause a noticeable pull, and the pull will be in the direction of the side with less caster. Ed makes another good point about tire wear also causing the car to pull to one side or the other. Have you tried switching the tires from side to side? How exactly are you measuring caster? If you are doing it by hand with a Smartcamber gauge and lines scribed on the ground, it can be difficult to achieve repeatable results. Triple check your measurements before getting out the die grinder.

If in doubt, you may want to have the measurements double-checked by a reputable alignment shop with computerized equipment. Besides easily and accurately measuring caster, a good technician with modern alignment equipment can measure steering axis inclination (also known as kingpin inclination) and setback, which are diagnostic angles that can identify bent suspension components and/or accident damage.

Is there any evidence of previous bodywork in the area of the strut towers? Most of the "problem" cars that we come across in terms of camber/caster settings have had evidence of one or both front quarter panels having been replaced and not properly lined up. We have even seen the adjustment holes jammed up with seam sealer/undercoating from the factory. We have resorted to slightly enlarging the holes to achieve proper alignment specs side to side in a few cases, but moderation is key and you want to be careful doing this!

Once you get your alignment settings correct, I would recommend installing the Weltmeister strut brace, as the end plates help to locate the entire strut top and plate, which helps to hold your alignment settings in place. Other strut braces only tie one or two of the strut mount bolts together, which does not do much.

DGC

Thanks to Ed and Chris,

Crossed front tires and drift switched. Since tires are not rotatable, guess
I'll cope with the drift for a few more miles. Adjustments have minimized drift
so it is tolerable.

My guess is that the corner balancing was never done properly when I bought
it new. Apparently driving with +110 pounds on LR/RF produced a bias in the tires.
Next set of tires will be rotatable...

Thanks Again,
DGC