Simple 912 Lowering

[doctor dave]

Hi all, I am lowering my 912 and it seems on the surface simple until I read the articles on how to do it! It seems that after disconnecting the torsion bar cover and the swing arm from the hub, can't I just pull out the TB and rotate it up a click and then shove it back in. That will lower the car some, and if not enough I can do it again. Then bolt 'er back up and away I go. Right? Don't see any need to make all those darn measurements. Am I missing something??

Thanks Dave

[djdsc]

Originally Posted by doctor dave

.......... Am I missing something??

Thanks Dave

Yes, experience.

Your right the process is just that simple......but then again.... it is not. When it all goes to hell and you are trying to find your way back to a starting point, you will be glad you took the time to have a reference point. There is a lot going other than just lowering the body closer to the ground.

In your reading I'm sure you have discovered several ways to reference a start, pick one and try it. Then the next time try another and find the one that works best for you.

Or not.

[Peter Graham]

The front is easy: a bolt on either side of the crossbar that changes the index of the torsion bar with respect to the a-arm.

The rear no so fast. There are a different number of splines on each end of the torsion bar. One spline change on one end will be too much change either way.

First: determine the unloaded angle of the spring plate to determine your basis of change. (Measure the starting angle of the spring plate hanging 'free' - banana arm unattached). Once you have separated the bar from the spring plate and the chassis, clean up the splines and apply a generous coating of antiseize. This will make subsequent adjustments much easier. Without fully seating the inner bushing (you replaced those, right?), replace the spring plate and measure the angle. Compare to original. Rinse, lather, repeat as necessary until you end up with the unloaded angle you need. There have been posts I've seen that correspond an angle with ride height: you need to difference yours for want you want. Remember the angle you want maybe a substantial twist to the bar's original position.

You may find that once the car is back on the ground and the suspension is settled that you got it all wrong. Adjustable spring plates (Elephant Racing's are nice) are a good way to circumvent this trial and error process.

'Good judgment is the result of experience and experience the result of bad judgment.' - Mark Twain

Good luck with your adjustments; you'll need to do a 4-wheel alignment when you're happy with the ride height. You might also give some thought to corner balance since you're going this route. You may have to make some concessions to alignment spec, specifically too much negative camber (AMHIK) - not bad with respect to handling; not great for tire wear.

Peter

[cmpski]

You did not mention if you had a SWB or LWB car. The angle you are looking for will differ some based on which one you have, Listen to Peter, he knows his stuff. Here are some links that might help. I would save the first one for future reference.
Chris


911 Spring Plate Angle Calculator

SWB Alignment and Corner Balance Complete!