83 911SC - Rear Ride Height Adjustment

[Das86TurboII]

Just finished rebuilding my suspension nose to tail. I can't find the specs for the rear ride height and where to measure it from. I have the specs for everything else. TIA

[HarryD]

Search is your friend.

My search found the following:

Quick way:

Fender ride height
~25" up front
~24.5" in the rear

Correct way:

Originally Posted by Bill Verburg

Only US 78-81 SC were set at the factory at the raised height
here's a survey of the specs


height is the difference between a & b

Helpful Thread: https://forums.pelicanparts.com/porsche-911-technical-forum/1137954-wheel-alignment-issues.html

There are many more. Search for Euro Ride Height.

[HarryD]

Also, you should get the Specification Book for your car: https://www.pelicanparts.com/More_Info/WKD423120.htm?pn=WKD-423-120-OEM&bc=c&q=specifcation%20book

[David Inc.]

I never saw that booklet! I love it!

[chrismorse]

If you are running shorter tires, like 205/50-15, the OD goes from about 25 inches to about 23, loosing a full inch of car height.
changing wheel diameter with the tires also affects the fender height.
Using the factory method gets the a arms/trailing arms at the designed angle to give the suspension a chance to function as designed and ignores any height changes caused by wheel and tire coices
And if you are using New Bilsteins, they will need to "settle", so don't get worried about having the chassis height perfect, initially. Maybe even an inch!!! It has been reported that this "Settling" could take from 200-500 miles??

i'd be greatfull for those that have been there and done it to comment on how much and how long this might take.

Is there a similar settling that occurs with new rubber bushings??

And Finally, for best results, you will need to borrow a set of scales to adjust the torsion bars/springs once you have the ride height set - this is a fussy process that involves rechecking heights and readjusting, repeatedly, but worth it in handling for high performance driving. more reading recommended.
HTH,
chris

[tsuter]

If you are already happy with the rear ride height, then when renovating my suspension I like to record the unloaded spring plate angle before I remove the old spring plate and torsion bar bushing.


Then when putting in the new spring plates (adjustable) I adjust back to the same angle as before....also unloaded. The car should not have been moved in the meantime.


The angle value really has no meaning but it ensures that your ride height remains the same as it was before the change out and that you get the new plate on the same torsion bar spline as before. The you can micro adjust if needed.

[Das86TurboII]

This is perfect! Thanks for all the replies! I have the factory manuals. They detail the font well but I didn't have the diagram at the top showing the measurements of the spring plate. I set the front end up with -1.0 degree negative camber, caster at 6 deg and ~1/8" toe in. Going to set up the rear now

[Das86TurboII]

In my opinion, do not. use the fender lip height. This could differ based on how the panels were installed, if the car had been in an accident etc. The earlier cars had many manual steps in their assembly. A body man (experienced P guy) told me he's seen a lot of variation in body panels. The preferred suspension set up is measuring off the actual suspension component center points as shown early in this thread. Thats what I'm going to use. My $0.02.

[Das86TurboII]

Question on the rear adjustments. I'm chasing the toe adjustment. Starting over, I've loosened the bolts connecting the spring plate to the rear hub. Both eccentric bolts are loose. I've positioned both so that the oval offset is in the neutral position. Essentially parallel to the spring plate axis. Does it matter if I start with the toe or camber? In adjusting the eccentric bolts what direction (up or down) do I turn them to get toe in? The same with the camber? TIA

[tsuter]

Setting front and rear alignment now is one thing that I just pay people to do but in my younger and poorer days I relied on this book by Ray Scruggs:

https://www.club911.net/divers/32tech/geometrie911.pdf

[Das86TurboII]

Thanks tsuter. Reading what you shared. Much appreciated!

[Das86TurboII]

Hi tsuter,
Pages 12 and 13 are missing from the link you sent. Do you have them by chance? TIA
Das

[tsuter]

No, I did not realize that. The scan in the link is clearly bad. Sorry about that. I have not done my own car's alignment this century so its been awhile to use any resources.

Here is a pretty good Pelican link though:

The Ray Scrugg's Home Alignment Method