E36 Rear Diff Bushings - how do they feel?

[m3panda]

For those who went with E36 rear diff bushings that are supposedly softer, would anyone care to share their real-world experience and review? All I read online are that they are made of softer rubber, but no real post-install real-world accounts of how they actually feel and impact to NVH.

Context:
The car underwent some modification alongside subframe reinforcement a while back (AKG poly subframe and diff bushings, Synchrodesign RTABs, OEM trailing arm ball joints).

As for the diff, went with the 95A AKG bushings, driveline is absolutely tightened up but no surprise, it's definitely louder.

By louder I mean > diff whine on highway speeds 70mph. Driveline clunking during gear engagement.

Sure I need to check other things like guibo, trans mount, etc. But seeing account of people recommending against the poly diff mounts has me wanting to go back to OEM diff bushings.

Front bushing is a direct replacement - so OK cool. But for the rears, as many of you know they don't sell them and only comes with a new diff cover. FCP is selling the diff cover for a whopping $499. So only economical choice here is the E36 bushing, or just live with the added driveline noise... Car is purely a weekender/track car, with slight lean towards track usage. Would be nice to soften things up a bit for the occasional street driving though.

[moproblems]

Solid subframe bushings and OEM/e36 diff bushings here. No complaints.

[jayjaya29]

I think the front diff bushing is the cause of the whine. You may be able to get away with just replacing that.

[samthejam]

The E36 M3 ones feel okay. No whine or anything with stock bushings. I wish I had bought a stock rear cover when it was cheaper just because that would match the front one. But the E36 M3 ones have 50k of street and track miles and they're fucked or anything.

[bmwfnatic]

At least the 2001 cars came with the E36 bushes from factory.
The weird foam bushes came later.

[Nate047]

They’re fine, I went through a whole dumb ordeal trying poly of various types and in the end, OEM front and E36 rear mounts work and don’t have any NVH. Sometimes the best answer is to just let good enough be good enough.

[fattycharged]

e36 work just fine and last a very long time, unlike the newer version….


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[R60BBA]

m3panda the ole rear diff bush conundrum.

As you correctly pointed out the E46 M3 rear diff bushes are nsp. Therefore if you want to replace them, you have to purchase the entire diff cover (which comes with the bushes already pressed in).

The E36 rear diff bushes are sold standalone and can be pressed into the E46 M3 diff cover. They are also cheaper. However, they are not M3 specific (it’s the same bush used across the entire E36 platform). They are softer than the E46 M3 rear diff bushes and are generally considered a performance downgrade.

It probably isn’t that noticeable, especially if the car is only used on the road. But I haven’t been in a car with them so cannot specifically comment.

If the car is a keeper then go for the E46 M3 rear diff cover (see if you can get a discount from your local BMW dealer). You track the car as well, so why have softer than OE bushes in the diff?

Although, if you do go down the E36 route, be sure to ensure that the bushes are installed the right way (as they are directional).

You touched on it but when changing the rear diff bushes, also be sure to change the front diff bush (which thankfully is sold standalone) and install the upgraded diff bolt (and washer) - p/n 33177840535.

The front diff bolt has a torque spec of 200NM, make sure this is adhered to otherwise you may end up with a clunk. There have been cases of it dislodging itself out of the thread.

[Ramps]

I have CMP sold subframe bushings and OE E36m3 rear diff bushings and it’s completely fine. The rear end feels nice and solid, no diff whine, no noticeable change in driveline feel etc. even on track.

[m3panda]

Sometimes the best answer is to just let good enough be good enough.

this resonates

Great insights and feedback, thanks for the discussion yall. Gonna send with the OEM front diff bushing + E36 rear diff cover bushings.