Say goodbye to rear end clunks and prevent total failure with the Rogue Engineering Rear Shock Mount!
The factory BMW rear shock mounts are generally a little soft, to provide the most possible acoustically dampening in the vehicle. However, design precludes them from being stout enough to withstand the rigors of aftermarket suspension, or even badly damaged roads. A decent sized pothole can send a perfectly good factory rear shock mount to pop out, making it entirely useless necessitating replacement. Upgrading to E46 M3 rear mounts (a popular alternative) is not a guarantee that it doesn't happen again and again.
Because of poor design and extensive abuse, stock BMW rear shock mounts mounts often fail with rubber deteriorating which then allows the inner metal sleeve to start moving (or eventually separate from the rubber). Usually, this manifests itself as squeaking, rattling, clunking and deflection of the rear shock mount, leading to poor suspension performance and a great deal of annoyance. Replacing the RSM's with OEM units provides temporary relief, but invariably they fail again, usually in 20K miles or so, but often MUCH less when aftermarket high performance shocks are used.