[seanblee]

Since having my Quaife installed a few hundred miles ago, together with M3 subframe bushes and uprated ARBs, I've noticed an occasional whine from the rear end when accelerating through 40mph. The load on the driveline has to be just right - it doesn't do it under hard or gentle acceleration, just moderate.

I initially blamed the diff, but the shop that installed it (Birds) assures me that a noisy diff would be noisy all the time, not just under specific loads. They suggested it might be the auto box as it was always happening in the same gear (5th), but I managed to repro it in sport mode in 4th tonight at the exact same road speed.

Has anyone else ever come across anything like this? Any suggestions what I should be getting them to fix?

Thanks in advance!

[335iSSA]

Sound anything like described in this thread:
http://www.e90post.com/forums/showthread.php?t=532595

specifically posts 1 and 32?

Originally Posted by seanblee

Since having my Quaife installed a few hundred miles ago, together with M3 subframe bushes and uprated ARBs, I've noticed an occasional whine from the rear end when accelerating through 40mph. The load on the driveline has to be just right - it doesn't do it under hard or gentle acceleration, just moderate.

I initially blamed the diff, but the shop that installed it is insistent that a noisy diff would be noisy all the time, not just under specific loads. They suggested it might be the auto box as it was always happening in the same gear (5th), but I managed to repro it in sport mode in 4th tonight at the exact same road speed.

Has anyone else ever come across anything like this? Any suggestions what I should be getting them to fix?

Thanks in advance!

[seanblee]

Yes, almost exactly! I guess I'm glad I'm not the only one, but it doesn't sound like you've been able to find a cure either Wonder where we go from here?

[335iSSA]

Originally Posted by seanblee

Yes, almost exactly! I guess I'm glad I'm not the only one, but it doesn't sound like you've been able to find a cure either Wonder where we go from here?

Based on the last symptom in this post:
http://www.e90post.com/forums/showpo...80&postcount=7

I am thinking it's the drive shaft. I am likely going to have my shop replace the whole shaft next week I'll report back.

Also based on communication with Autobahn335i he had the sway's put on at a later time and the whole subframe replaced due to an accident. So from this I am thinking these are not part of the problem, leaving only the drive shaft...

[seanblee]

Are you thinking the shaft was somehow damaged when the diff was installed? My shop has installed dozens of these, so I'd be surprised if that's the case for me, but I guess it's possible. Perhaps it's been there all along but had been damped by the standard subframe bushes?

[335iSSA]

Originally Posted by seanblee

Are you thinking the shaft was somehow damaged when the diff was installed? My shop has installed dozens of these, so I'd be surprised if that's the case for me, but I guess it's possible. Perhaps it's been there all along but had been damped by the standard subframe bushes?

I'm not sure but I wasn't having the issue before going in to have the install done. Through process of elimination this is our next step. The shop I chose has done doznes of thee installs as well. Sometimes things happen.

I think if there was a balance issue before you would know it, the bushes wouldn't mask this significant of an issue.

[Orb]

Originally Posted by 335iSSA

I'm not sure but I wasn't having the issue before going in to have the install done. Through process of elimination this is our next step. The shop I chose has done doznes of thee installs as well. Sometimes things happen.

I think if there was a balance issue before you would know it, the bushes wouldn't mask this significant of an issue.

Check the drive shaft support bearing....this has happen before.

[tscdennab]

Originally Posted by Orb

Check the drive shaft support bearing....this has happen before.

I read one thread where the support of the bearing was installed up side down. It can very easily be installed upside down, resulting in a vibration at certain mphs.

Here:

http://www.e90post.com/forums/showthread.php?t=621437

See posts 16 and 17, and the rest...

[seanblee]

Birds tell me the centre prop bearing wasn't touched when my install was carried out, and there's no reason it should be touched to install the diff. I'm therefore hopeful this isn't my issue.

[Orb]

Originally Posted by tscdennab

I read one thread where the support of the bearing was installed up side down. It can very easily be installed upside down, resulting in a vibration at certain mphs.

Here:

http://www.e90post.com/forums/showthread.php?t=621437

See posts 16 and 17, and the rest...

Any whine noise is going to be a bearing which one is the hard part

[Joshboody]

Likely if the shop has done an E90 pumpkin before, they didn't drop the center bearing... not needed.

[335iSSA]

Originally Posted by Orb

Check the drive shaft support bearing....this has happen before.

I had the shop replace the drive shaft, which included a new flex disc (gubio) and center bearing. This is not the problem. Still trying to find the issue.

[Orb]

Originally Posted by 335iSSA

I had the shop replace the drive shaft, which included a new flex disc (gubio) and center bearing. This is not the problem. Still trying to find the issue.

It would be best to look at all things that worked on during the install. When the bearing are in good condition the noise is usually caused by lose race condition or possible a bearing race not being seated properly. It can be difficutl to see the with the eye as the diviation might be small. When the noise happen is subjective so it could happen for specific load/speed or all the time but it will be more prevalent when things warm. The nature of the noise is the bearing vibrating at resonate frequency so it can be damaging long term. Theis give you the idea why it happening but i not sure anyone can help pin point it

[seanblee]

FTR, unbeknown to me, my car actually received Powerflex designed bush inserts instead of the OE BMW M3 versions. Birds have removed these and the noise is gone, so it's evidently a resonance issue that gets carried through the subframe bushes into the body but is absorbed by the standard sloppy bushes. I'm going to live with the slop for the time being.