Rear Spring Plate Bushings

The rear suspension components include a flat spring plate with a tubular torsion bar carrier welded on and rubber bushings on both sides, a rear bearing cover and a torsion bar. Last weekend I took the rear bearing cover off to inspect the rubber outer rubber bushings on both the right and left sides.

Over the years the rubber bushings have sagged to the point that both bearing covers are rubbing against the torsion bar carrier (carrier is not the correct name for this part). The rubber bushings are supposed to center the carrier in the bearing cover. Both rubber bushings are shot. The outer ones are replaceable, but the inner ones were originally vulcanized to the carrier. The factory expects you to replace the entire spring plate with the attached inner rubber bushing at a cost of over $300 per side.

For $70 you can get a set of inner and outer after market plastic bushings for both sides. These are commonly used for competition and are not ideal for the street. They are harder than the rubber and as a result do a poorer job of insulating the body from the suspension. Further they will tend to squeak as the lubrication washes away. I installed these rather than spending $700 on new spring plates.

At the bottom of this page are 4 pictures taken while putting in the new plastic bushings.


110400-18 The rubber bushings have sagged to the point that the torsion bar carrier is against the bearing cover. The bushings need to be replaced.
110400-19 To remove the bearing cover, the spring plate must be unloaded from the bottom-most bolt. This bolt even has a replaceable metal bushing. Place jack-stands under the torsion bar tube to support the rear of the car. Then you can lift the suspension at the lower shock attach point which will allow the bolts to be removed from the bearing carrier without any tension from the spring plate.
110400-20 The bearing cover is needs cleaning up, but has no rust. There was an article in the Aug 1989 Pano (Up-Fixin der Porsche Vol 8) that describes replacing these carriers because they had rusted through. You can see that the rubber bushing is permanently distorted and needs to be replaced.
110400-21 Here is the torsion bar carrier welded to the spring plate. Notice the accumulated rubber + dirt + scale on the carrier surface under the rubber bushing. When new bushings are installed, this area will have to be cleaned up.
110400-29 This shows the spring plate detail on the right side of the car. I have knocked some of the accumulated rubber and scale off before the picture was taken. Notice the wear mark on the carrier from the bearing cover rubbing on it because the rubber bushings have sagged.
111100-45 To replace the bushings, the spring plate must be free from the swing arm. This is done by first removing the lower end of the shock. Then the four connections to the swing arm. Note the position of the two eccentric bolts which have off center heads. These bolts are used to for suspension alignment. Next remove the retaining bolts from the bearing cover and pry it off.
111100-47 Remove the body plug and pull the spring plate out. In my case one side pulled the inner torsion bar connection free and the other side the outer came free. To free the outer torsion bar, I drilled a hole in the cap and tapped the torsion bar free as shown in this picture.
111100-53 Clean up all four rubber bearing surfaces, smear the silicone lubricant on the new bushings and reassemble.
111100-54 Reassemble, resetting the spring plate angle the same as it was (unless you are changing the ride height). The torque values are:
Bearing cover bolts34 ft-lb
Spring plate to swing arm65 ft-lb
Camber eccentric bolt36 ft-lb
Tracking eccenter bolt43 ft-lb
Shock retaining bolt54 ft-lb
The car should be re-aligned (rear camber and tracking) after this procedure.
Last modified: Sat, 11 Nov 2000


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