Dropped the diff last night and removed the rear diff bushing. Came out pretty easily, just a bit tricky coming up with a combination of tools that would pull it out
I have received these bushings from FCP
2x M3 front diff bushings 33312284019 - These bushings fit the stock non M subframe no issues
1x F series rear diff bushing 33316792514 - This bushing has a metal ring around it vs the split stock bushing. Looks like there may be less voids in the rubber. Have confirmed it DOES fit.
1x Stock rear diff bushing 33176770866 - Just a stock standard Lemforder rear diff bush
1x M3 rear diff bush 33312283384 - This bushing is significantly smaller, made from polyurethane and is quite soft, but has no voids in it. This bushing could indeed be made to fit a non M subframe. An aluminium sleeve could be made so that the bushing can be pressed into the sleeve, then the assembly can be pressed into the subframe.
Since the F series rear diff bushing is the same size, there is a decent chance the front ones could fit too. While we already have the M3 front bushings to choose, RealOEM has recently been updated to include the M235i racing, which has all the part numbers for the upgraded parts used. The M235i racing is basically a production racing car, and has upgraded bushings and suspension arms.
http://www.realoem.com/bmw/enUS/show...diagId=33_1830
Looks like it has upgraded bushings, although they specify 2 units for the rear diff bushing, so it might be a 2 piece poly unit, which I would not be interested in.
Aftermarket polyurethane bushes like Nolathane and Whiteline are great for the subframe but terrible for the diff. Will get thumps and clunks on transition on power and coast and can introduce diff whine. I wanted an oem bushing that wont introduce noise for my daily driven car. The mfactory diff bushings could be another option, but they are solid and not quite sure what to expect for NVH. I would prefer an OEM option as they will be on the more conservative side and guaranteed to fit well.
The installation itself for the rear bushing wasnt too difficult, I removed the vbrace, exhaust, underbody heatshielding and differential.
The bushing came out very easy but took me quite a while to assemble the correct combination of tools to pull it out. As you can see the bushing was very torn and was further damaged by the removal process. Still need to install the M3 front bushings.