lowering the rear

[trond]

I want to raise my 80SC in the rear to gain more suspension travel, and believe I can use the eccentric bolt on the torsion plate/spring plate. I unloaded the rear suspension by removing the stop bolt and sleeve and disconnected the shocks. The torsion plate angle was 24 degrees, as opposed to US spec 40 and Euro spec 34 so the car is low in the rear.

Must I loosen the spring plate from the spindle and loose all alignment ?

[Joe Bob]

Typically you lower/raise the rear with an adjustable spring plate by adjusting the spring plate eccentric bolt.....any adjustment would suggest an alignment check. BOTH front and rear.

Re-indexing the rear is for more than 1 inch adjustment. When was the last time you had an alignment or corner balance?

But I could be wrong.....

[stlrj]

Assuming you have the rear raised up, you have to add the angle of your car from level to the 24 degrees. So, if the angle of your door threashold is 8 degrees from level, then your spring plate angle is really 32 degrees.

Your spring angle is based on a level chassis.

[trond]

I included the door sill measurement. Will I need to loosen the torsion plate from the banana arm/wheel spindle to make adjustment on the eccentric bolt ? I think yes..... I did have a shop look at it before I shipped the car from the US but it appears they just had a look from a distance. At speed on bad roads the car is poorly balanced and handling is scary. For now I just want to experiment a bit and see how raising the rear to something close to Euro spec affects handling. I would prefer not to upset camber and toe too much because alignment is hard to get done where I live, and my car would be out of commission. I realize I will have to get balancing and alignment done but that will have to be later when/if i can find someone to do it or I have got the tools myself

[Joe Bob]

" Experimenting" + high speed = Muerte......

Get it aligned......

[Flieger]

I would wait until you can get an alignment. I think having the rear low is not as bad as having a bad alignment. Toe-out or bad camber can cause much more instability than a low ride height. My car was quite low in the rear and one spring plate ad been installed 5 degrees off from the other and the handling was not that bad since the algnment was conservative. I just ahd all bushings replaced with bearings but I also raised the rear and got a more aggressive alignment with all the camber and caster I could get. I also got less rear toe and some front toe-out. The car is much more twitchy now but it is controllable and smooth because of the smooth bearings.

[trond]

Must I loosen the two bolts attaching the sping plate to the banana arm (hidden behind the caliper in the picture) to use the eccentric height adjuster or not ?

Will I also have to touch camber and toe adjustment bolts (except to compensate for change in geometry with change in height) ? yes/no

[stlrj]

Must I loosen the two bolts attaching the sping plate to the banana arm (hidden behind the caliper in the picture) to use the eccentric height adjuster or not ? Yes

Will I also have to touch camber and toe adjustment bolts (except to compensate for change in geometry with change in height) ? No

But you might do yourself a favor and do a search. You will need a special thin wrench to fit benind the spring plate that can be obtained from a bicycle shop. I can't remember the size, 36mm?

Also, make sure you index the original position so you know where you started.

I also have raised my rear end and you will not have to worry about the alignment. I already checked mine before and after...nothing significant.

[Trackrash]

Measure your rear height and tell us what you have now. Measure from the fender lip to the ground on both sides. Why do you think it is too low?
If it really is too low you may want to have the suspension checked over by a Porsche expert to see why it is too low. I would want to know that all the bushings and torsions are in good condition before I started making adjustments.
As others have stated rear alignment (including corner balancing) is critical to safety and good handling.

[trond]

did the adjustment and that went easy enough. After disconnecting shock and sway bar I adjusted the rear right torsion plate angle from 22-24 degrees to the prescribed 32 degrees by the eccentric bolt (using the calculator found here on the forum). The left rear was already at 32 degrees. It got late and I didn't test it yet on the road, but at least now it looks right. Hard to understand what the previous owner or his wrench was thinking there. I'll do an approx level setting for the front too then once I am in the ballpark a proper alignment whenever I can find a shop.

Edit: took the car for a spin in the rain and the problem I had with corner stability appears to be gone and the rear suspension works well. At 32 degrees I measured the ride hight to (very) approx 0 mm, which is about 1/2" lower than Euro spec.

[RoninLB]

as per nice picture

the lock bolt has to be very tight or that end will sag sooner or later

without looking it up in text i'd guess 100-125 pound feet
60-75# ain't gonna do it imho