HELP - Modulating Whirring Sound From Diff or Rear End Area???

[DrFerry]

I have a modulating whirring sound coming from the differential rear end area at about 20mph, regardless of gear. Could this sound be from a wheel bearing, or the differential nose bearing, or perhaps a driveshaft bearing? Sound clip link below.

The recording was made with the rear seats down. Listen for the modulating wah-wah type sound. The car makes the noise when coasting in neutral, or at steady state speed of 20mph.

I do have 12mm spacers, so I am wondering if perhaps the whirring sound is a driveshaft bearing? Who knows? Opinions please. The sound clip can be heard best on mobile phone speakers or with computer speakers, but not with ear buds which seem to boost the bass too much. Take a listen.

https://soundcloud.com/user-90547482/diff-whirring

[Diffsonline]

you have solid subframe bushings... I would start with returning those to stock.

[///M Power-Belgium]

Originally Posted by M3Post

I have a modulating whirring sound coming from the differential rear end area at about 20mph, regardless of gear. Could this sound be from a wheel bearing, or the differential nose bearing, or perhaps a driveshaft bearing? Sound clip link below.

The recording was made with the rear seats down. Listen for the modulating wah-wah type sound. The car makes the noise when coasting in neutral, or at steady state speed of 20mph.

I do have 12mm spacers, so I am wondering if perhaps the whirring sound is a driveshaft bearing? Who knows? Opinions please. The sound clip can be heard best on mobile phone speakers or with computer speakers, but not with ear buds which seem to boost the bass too much. Take a listen.

https://soundcloud.com/user-90547482/diff-whirring

Yeah . With my previous BMW I had a similar noise coming from the rear end of the car .
The outcome was a worn wheel bearing .

[SAMM3Y]

Originally Posted by M3Post

Well my car has now been in the shop for a week on a lift since December 10th, and no progress has been made except for the Differential being removed and delivered to the transmission shop.

The transmission shop repairing my differential called me on Wednesday Dec-12th prior to their ordering parts (all of the bearings and seals). Yesterday (Monday 12/17) - to check on progress - my 'Indy shop' called the transmission shop who stated "Diff repair parts were not expected in until today = Tuesday Dec-18th!"

I'm guessing the transmission shop had the parts shipped via ground.. or the parts are coming from the Antarctic. Anyway, perhaps the moral of the story is (at least so far) IF you are going to get your Differential pinion bearing or carrier bearings or even seals repaired then have all of the parts 'on hand' in advance. Frustratingly slow progress.

Craigslist a spare diff and sell on after you get yours sorted? they're painless to change.

[driftflo]

Originally Posted by M3Post

It turns out the was noise from a bad carrier bearing. Many of the bearing rollers were heavily pitted and so was the bearing race. I could find no part numbers, manufacturer name, nor the country of manufacture on any of the parts. The car now drives much quieter. The whirring noise has gone!

Total cost for removal, installation, differential repair labor, new parts etc. was $2384. Still cheaper than buying a new Diff, and i get to keep my shorter ring and pinion gear set (3:45) - as well as my Quaife LSD.

Sure hope these bearings last longer than the old ones. Perhaps the pre-load was too tight? Comments would be appreciated.

this was obviously an installation error of the person who installed the gearset/quaife. this is no normal wear and these side bearings are rock solid and do fail very very very rarely. and these ones look really horrible...

furthermore, if there is no manufacturer name on them it could be there has been used poor quality noname stuff when installing the quaife?!

i hope the fix has been done by another shop now and they used OE bearings and have (and know how to use) the tools to set dynamic friction values right.
if they did not set it right you will have the same problem again, soon!

[///M Power-Belgium]

Glad you figured out what it was . Good job !

[Richbot]

Originally Posted by driftflo

this was obviously an installation error of the person who installed the gearset/quaife. this is no normal wear and these side bearings are rock solid and do fail very very very rarely. and these ones look really horrible...

furthermore, if there is no manufacturer name on them it could be there has been used poor quality noname stuff when installing the quaife?!

i hope the fix has been done by another shop now and they used OE bearings and have (and know how to use) the tools to set dynamic friction values right.
if they did not set it right you will have the same problem again, soon!

That was my thought, what bearing company of any repute doesn't at least laser etch a name to avoid counterfeit claims?

wtf

[DrFerry]

Originally Posted by ///M Power-Belgium

Yeah . With my previous BMW I had a similar noise coming from the rear end of the car .
The outcome was a worn wheel bearing .

It turns out the noise from a bad carrier bearing. Many of the bearing rollers were heavily pitted and so was the bearing race. I could find no part numbers, manufacturer name, nor the country of manufacture on any of the parts. The car now drives much quieter. The whirring noise has gone! Total cost for removal, installation, differential repair labor, new parts etc. was $2384. Still cheaper than buying a new Diff, and I get to keep my shorter ring and pinion gear set (3:45) - as well as my Quaife LSD.

Sure hope these bearings last longer than the old ones. Perhaps the pre-load was too tight? Comments would be appreciated.
.

[DrFerry]

IF I had to do it all again I would've bought a Diff from driftflo.