This project started because I wanted to get my ‘80SC to ‘Euro’ ride height, which is 25.0” rear and 25.5” front, when measuring from the ground to the top-most part of the wheel well arch. This really improves the looks and handling of the car.
Jack the car up and support it with jack stand on the INSIDE portion of the torsion bar tube. Scribe the position of the spring plate against the inner wheel well to use as a reference in case you need to start over, or, re-index the spring plate on the torsion bar. The reference mark is made BEFORE disconnecting from the trailing arm, you’ll make two more reference marks later.
Disconnect the shock to allow tension to be taken off the torsion bar. 24mm socket/wrench if I recall. NOTE: you should always support the trailing-arm with the jack. I removed mine to snap the picture. This also allows for easier removal of the shock bolt as there is no tension on it.
Keep the trailing-arm supported with a floor jack to keep full weight off the axle and CV joints. You can fine-tune the height in order to remove the camber, toe-in, and connector bolts since there is tension on them.
Remove the spring plate bracket, 4 bolts. There is also a spacer behind the bracket at the lowest hole.
Once the spring plate is fully disconnected from the trailing- arm and the bracket has been removed, scribe another mark against the rear wheel well. Again, this will be a reference to get things back to your starting point should you run into trouble along the way.
Take a measurement from the bottom most edge of the spring plate to the floor. In my case this was 8.75 inches. My current ride height was 26.25 and I needed to come down to 25.0, a difference of 1.25 inches. I removed the spring plate from the torsion bar and rotated the spring plate up, away from the ground until the measurement on the ruler was 10 inches. Luckily, there was a spline on the torsion bar at this location and I was able to slide the spring plate back on and keep the proper measurement. It appears that if you need to lower the car 1”, you can rotate the spring plate up 1”to get the desired results. I think I was extremely lucky since I got exactly 25.0 inches when I was done. In any case, this should get you close and you can do a fine adjustment using the eccentric bolt on the adjustable spring plate. If your spring plates are not adjustable, you will need to be a bit more exact. It may be wise to find adjustable spring plates from a later 911, or purchase a set of the Sway-A-Way adjustable spring plates from Pelican Parts
Then, you can fully remove the spring plate, exposing the torsion bar. NOTE: You should scribe yet another mark once you get the spring plate to the height you want in the previous step. I DID NOT do that here and had to futz with things a bit to get it where I needed it. The third scribe mark should lie between the two existing scribe marks. I did not make this mistake on the other side and it went much easier. You will need to remove the torsion bar access hole on the outside of your rocker panel in order to fully remove and adjust the spring plate. It is just a matter of loosening a nut and removing the cover itself and the seal.
Now for the fun part, removing the old, hard, extremely stuck bushings. I started with a utility knife and made multiple vertical cuts around the whole bushing.
Then, I used an old and DULL chisel to pry the pieces away from the spring plate, using the gentle coercion of a hammer.
Finally, I spent $2.50on a wire wheel for my bench grinder to take the rest of the old rubber off. What a nasty job! This really does the trick, though. Once everything was cleaned up I put a nice coat of black metallic paint on the spring plate to match my car, wire brushed the spring plate bracket and bolts/nuts.
Next, I installed the new Neatrix bushings. Make sure the surface where the bushing goes onto the spring plate is clean. Glue the new Neatrix bushings to the spring plate using the epoxy included w/bushings or use some other strong adhesive. Let glue setup completely, perhaps overnight. When dry, install spring plate with new bushings into in the torsion tube. Use baby powder or soap if needed to ease installation into tube. DO NOT USE GREASE OR ANY OTHER PETROLIUM-BASED PRODUCTS, AS THEY WILL BREAK DOWN THE RUBBER. I was careful to install the spring plate on the torsion bar using the reference mark I had made earlier. Once things were measured and checked, I re-connected the spring plate. NOTE: If your measurement is off a bit you can use the eccentric bolt on the spring plate to fine-adjust. This requires a really thin 36mm wrench because you need to fit it between the spring plate and the wheel well. Good news, you can head to your local bike shop and purchase one for $15.00 or so. Bikers use this for adjusting the headset on the bike. Plus, you’ll save big bucks over the specialized wrench sold through catalogs. When re-connecting the spring plate to the trailing-arm, you may need to fine adjust the height using the floor jack so the holes line up.
Well, it was a hard, dirty project, but well worth it. Here is the finished product, 25.0 inches the first try J. NOTE: If your ride height is off you can make the same adjustment to the eccentric bolt on the spring plate mentioned earlier.
Once the project is complete you’ll need to get an alignment done. I had the shop set the camber to negative 1 degrees at all corners. You may want to have your car corner-balanced as well. My car handles like a dream!