Solid rear end stuff = NVH. Is URO diff cover any good?

[m3panda]

Replaced few items during rear-end refresh + RACP reinforcement and getting quite a bit of NVH. Built the car to be weekend / DE car, with the goal of keeping it comfortable enough for cruises to and back from track.

Current setup:
- OEM RCABs
- Syncro Design RTABs
- AKG 95A Subframe bushings
- AKG 95A Diff bushings
- Bimmerworld Race RSM
- Rogue articulating height-adjutable spring perches

Driving around town - I hear clacks coming from the rear on low speed sharp bumps. Has anyone experience NVH coming from Rogue spring perches? Trying to pinpoint if the clacking is coming from RSMs or spring perches.

Secondly, getting a pretty noticeable diff whine around 70-80mph. Planning on going back to OEM diff bushings. Learned that it's not possible to get OEM rear bushings - anyone here have experience with URO diff covers? OEM BMW ones are like $650+, whereas URO one is $160 – 200.

[jayjaya29]

The clack noise is 10000% from the spherical rear shock mounts, switch to something with rubber or poly and the noise will go away.

For the diff cover bushings, the E36M3 rubber bushings press right in. They are a touch softer then the stock foam bushings but I doubt it will be noticeable. You may be able to get away with only replacing the front diff bushing to get rid of the whine.

[Ramps]

I’ve had those spring perches for 12 years, they don’t make noise. I also have solid subframe bushings, but rubber everywhere else, including E36M3 rear diff bushings and the car feels great. No noises, no diff whine.

[discoelk]

Poly diff bushings are likely the heaviest contributor to your whine noise.

[Slideways]

Given that the price of the diff cover is way more than it used to be, grab a new factory front diff bushing and the E36 M3 rubber diff cover bushings as jay pointed out. Best solution currently.

[m3panda]

Thanks guys- will give the e36 diff bushings and either Rogue / Bimmerworld street RSMs a try.

[Nate047]

Just curious, why did you go with poly subframe bushes instead of solid?

[jayjaya29]

Thanks guys- will give the e36 diff bushings and either Rogue / Bimmerworld street RSMs a try.

Dont forget to switch the front diff bushing back to stock. I did the e36 diff cover bushings and a poly front bushing and it whined. Thats why I suggested you may be able to get away with replacing just the front diff bushing.

[m3panda]

Just curious, why did you go with poly subframe bushes instead of solid?

good question- the 95a subframe and diff bushing was recommended to me by the previous mechanic. He ended up going silent and I ended up just trying out already-purchased parts with a new shop. Looking back now I would’ve gone with solid subframe bushings and OE diff cover & bushing.

Did some light search on 95a vs solid out of curiosity too myself, there are some mentions about poly bushings having better contact area with the mounting area. But given that poly will wear out over time maybe solid is better.

[Nardo S54]

Diff whine doesn’t bother me. Kinda dig it… but the clunking from spherical rear shock mounts drove me nuts. Switched to Rogue and all that went away.

[AWE46M3]

Poly diff bushings are likely the heaviest contributor to your whine noise.

+1. I did the big 3 within the first 1,000 miles of owning my car and let the shop handle it before I really knew any better. They installed the same bushings you have:

AKG 95A subframe bushings

AKG 95A diff bushings

The diff whine drives me nuts, so I’m planning to drop the rear and replace both bushings in the not-so-distant future.

[BL92]

Can i still run standard BMW bushes once the vince plates are installed ?

CMP mentiones using higher bushes to make up for the height/gap of the plates

only asking cause the PO changed the bushes on mine 12,000 miles ago