Fine Tuning Rear Torsen Bars

[jluetjen]

I've been working on setting the ride height and corner weighting my car, and I've been tossing and turning at night about fine tuning the rear T-bar settings. Both Bruce Anderson and the factory shop manual describe that the smallest increment is 50 minutes of adjustment (up 1 on the inside (9 degrees) and down 1 on the outside (-8 degrees, 10 minutes)). I kept thinking that this didn't make sense. That there must be some way to adjust the bar in increments of 10 minutes and then it hit me. Does this make sense. Note that I've converted minutes to fractions.

Inside/outside adjustment = effect.
up 1 / down 0 = up 9 degrees or 54/6 of a degree.
up 1 / down 1 = up 5/6 of a degree.
up 2 / down 2 = up 10/6 of a degree
up 3 / down 3 = up 15 / 6 of a degree
etc.
up 11 / down 11 = up 55/6 of a degree
>>> up (11-1=)10 / down 11 = up 55/6 - 54/6 = up 1/6 of a degree or 10 minutes!

I won't be able to try this out until Friday or Monday, but does the logic work? I figure that if I keep track of the changes and the affect on the ride height/corner weights I should be able to zero in within 3 or 4 tries on the rear end.

[dad911]

For what its worth, when I changed my rear torsion bars, I got the ride height close. Then I jacked up the car, levelled it side to side, and with a digital level on the door sills made sure both sides were at the same angle. Now the body is level side to side and at the same angle front to back.

Then I measured the angle of the spring plate on 1 side, and rotated the torsion bar on the other side until I got the same angle. Your correct in that rotating the torsion bar cw & the spring plate ccw will change the angle of the spring plate to the body.

I think you will pulll your hair out trying to adjust corner balance this way, as camber adjustment will affect corner balance. If you don't have them all ready, try to find a set of adjustable spring plates. Fine tune with them after ride height and alignment are adjusted.

[widebody911]

This may or may not be helpful:

http://www.vintagebus.com/cgi-bin/spring.cgi

[bhaubold]

John,

When you are adjusting the arms, be sure to pull up any slack (when the arm is loose) before you take your reading. Reading the angle with the arm hanging will give you a false angle.

[jluetjen]

Thanks for the information everyone.
The "Ah HA!" moment for me was the realization that adjustments less then 50 minutes could be accomplished. 50 minutes seemed like a fairly large increment when trying to corner weight the car.
I'd like to go the adjustable spring plate route but unfortunately I'm between jobs right now. So I've got time, but don't want to spend the cash. As a result I'm doing it the old fashioned way right now.

Thanks again.

[marcesq]

John:

You may want to try the following since you don't have the adjustable s-plates.

Determine desired ride height. Support control arm. Remove shock bolt. Remove 2 bolts that hold spring plate to control arm. Allow spring plate to drop to its lowest point and measure from ground to lowest point on spring plate. Add (or subtract) difference between current ride height and desired ride height to the measurement (add to lower car, subtract to raise car). Now adjust spring plate to new measurement by moving torsion bar cover up or down. If moving the cover does not acheive the new measurement, then rotate the inner splines of the torsion bar one spline and retry.

When I did mine they were dead on, i.e. both side at the same height and angle. It is easier to rotate the t-bar a couple of times to find the measurement, than putting everything together and finding that one side is 1/4" off and everything comes off one side.

I hope this helps.