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Rear Subframe Bushings

    Although I plan to stick with OEM M Roadster suspension parts and rubber bushings in most places, based upon input from those much wiser than I in the ways of the Z3 platform, the use of polyurethane bushings to mount the rear subframe can possibly extend subframe spot weld longevity. I was initially going to go with the Ireland Engineering poly rear subframe bushings (RSBs), but they were back ordered and I have heard rumors of quality issues, so I ended up with Powerflex parts. I installed the purple “Street” durometer, which is rated at 80A, approximately 30% stiffer than a rubber bushing. The Powerflex black race bushing durometer is 95A, approximately 80% stiffer than a rubber bushing.

    Powerflex Street Durometer RSB and a Removed OEM RSB
    Powerflex Street Durometer RSB and a Removed OEM RSB
    Powerflex Rear Subframe Bushing Installed

    My OEM bushings were fine, and I haven’t noticed much of a difference after the Powerflex installation, but it will be one less thing to do when I eventually tackle reinforcing the rear subframe assembly with the Randy Forbes kit I have on the shelf.