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The rear shock mounts (RSMs) on the E36 M3 are prone to premature failure.
Normally the factory rear speakers and the trunk's interior side panels have to be completely removed to gain access to these mounts for removal and installation, which is a major hassle especially when you have adjustable shocks that have to be removed from the car for adjustment.
There are a few aftermarket replacement solutions that have the mounting studs on a plate that mounts down through the shock tower from inside the trunk to allow future removal and installation of the shock from just the outside of the car, but most of them use polyurethane bushings which can create a harsher ride and increase road noise compared to the factory rubber RSMs.
Another common alternative is to replace the original E36 M3 RSMs with factory RSMs from an E46 M3 (2000 and up), which are a direct fit and still made of rubber, but are a better design that won't deteriorate as quickly as the E36 M3 RSMs.
However, the E46 M3 RSMs still have to be installed from inside the trunk, so custom mounting plates with studs, similar to some of the aftermarket mounts, were fabricated using the shock tower reinforcement plates from a BMW Z3 to work with slightly modified E46 M3 RSMs.
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E36 M3 RSM vs. E46 M3 RSM
Here are the two different factory mounts side by side.
The differences are subtle but significant to improve their life span.
You can see in the photo that the metal sleeve in the old E36 M3 RSM has already separated from the rubber bushing.
The gasket has also deteriorated and was no longer providing a weather-proof seal.
BMW E46 M3 RSM Part#: 33 52 6 754 096
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Z3 Reinforcement Plates
These are shock tower reinforcement plates for the BMW Z3, but fit perfectly in place on the E36 M3 shock towers.
New gaskets were hand cut from a thicker gasket material sheet for a better weather-proof seal than the micro-thin factory gaskets provide.
BMW Z3 Plate Part#: 51 71 8 413 359 |
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Reinforcement Plates with Studs
New M8x1.25x20mm 10.9 grade bolts were tach welded to the reinforcement plates and the plates were painted to prevent corrosion.
These plates will mount from the inside of the trunk with the studs down through the shock tower and will also reinforce the shock tower when the installation is complete.
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Modified E46 RSMs
The studs were pressed out of the E46 M3 RSMs to allow them to mount to the studs of the reinforcement plates that are now visible and accessible from the outside of the car in the wheel wells.
There is no need to enlarge or modify the stud holes, and the studs can be easily pressed back in if the RSM needs to be returned for warranty replacement. |
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RSMs and Reinforcement Plates Assembled
The shocks and new RSMs can now be easily removed and reinstalled for service or adjustment without having to remove the factory rear speakers and interior panels to gain access to the RSMs from inside the trunk.
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