Torsion Bars

[ericleach]

I have a simple question about torsion bars, mainly the rear bars.
I have a 70' 911 and adjusted the ride hieght to Euro Spec. First I adjusted the left and right radius arm to have the same angle. Put everyhting together and drove the car. It turns out that the left side height is considerably lower than the right. Even though the radius arms are at the same angle. After a massive headache and a couple of tries later I finally got the ride hieght correct on both sides. BUT. The radius arm on the left side is at a angle of 3-4 degrees greater than the right.

I was wondering if the torsion Bar on the left side is worn out, or could be a tweeked frame or something that I missed.

Do Torsion Bars actually wear out, or loose there rigidity.

Thanks Eric

[john walker's workshop]

how's the front height? uneven front height affects the rear, diagonally. the rear is a pain to align without an alignment rack. you might have to bite the bullet and have it pro aligned. if anything is bent, they'll find it. don't go to any old shop. find one that has a good rep in porsche circles. midas can't do it, even if they say they can. torsion bars do take a set after many years, but usually both settle the same. the spring plate bushings should be renewed before the align. they're usually quite worn.

[masraum]

Chances are strong that the corner balance is all out of whack now too (probably part of the problem). I would take the car to a good 911 shop and have them check the corner balance, height and alignment (don't forget lowering changes the toe-in which greatly affects drivability).
Driving a car with bad corner balance can be dangerous, cause odd things to happen at the limit, and cause really bad things to happen under braking.

[JerRed]

Eric,

I have the same problem, and have decided to change out my torsion rods all around, since I plan to track the car in the future.

Even with my corner balance right, and the angle set the same, the car is low on the left.

[911pcars]

The basic rule is that the front and/or rear ride height affects the opposite end of the car. In addition, when one adjusting one corner, the diagonal corner height is affected.

Here's one way to tell if the front end is affecting the rear ride height. First, remove one of the rear sway bar drop links. Then jack up the front end and support it at a single point; that being the middle of the front suspension crossmember. If you've got the jack point centered at this point, you've eliminated any effects of uneven front height settings and have isolated each individual rear wheel.

Measure the LR and RR heights (floor to top of wheel well will do). If they're uneven, adjust the spring plate/torsion bar settings accordingly. Once you know the rear end is even, you can see how much the front end settings are affecting the rears. Adjust LF and RF until the ride height is about the same and the adjustments affect LR and RR equally.

You can also use this basic procedure to isolate the front end. Once the ride height is set, corner balance the car. This process may result in slightly uneven ride height settings, but the chassis should be better for it.

Sherwood Lee
Here's a corner balance worksheet when you get to that point
http://members.rennlist.org/911pcars/cornerbalance.htm