[MF3series]

Afternoon

I have a 2010 E91. After purchasing (at c48k miles) the diff bearing failed and was changed within a week or so on buying it. It was replaced and seemed to solve the issue. It failed again at 56k and 63k and bearing was replaced again both times, each time the bearing noise from the diff starts out only slight and get worse and worse but fine after replacement. Now at 72k miles its gone again.

I have been told it just a bad diff in that model/year and i need to replace the whole diff.

Anyone offer any advice on this please?

Many thanks

Marcus

[mweisdorfer]

I rarely ever read about bad differentials on this forum. I'd say the differential on the E90 is fairly stout as long as the oil has been changed at regular intervals.

If your differential is shot, now would be a good time to upgrade to an LSD diff. Do your research and decide on which one.

1) M-factory
2) Wave Track
3) M3
4) Quaife

They are much better for winter driving. Unless you track the car, or canyon carve, you probably won't see much of a difference when spiritedly driving the car on normal roads. That's the only drawback.

[MF3series]

Originally Posted by mweisdorfer

I rarely ever read about bad differentials on this forum. I'd say the differential on the E90 is fairly stout as long as the oil has been changed at regular intervals.

If your differential is shot, now would be a good time to upgrade to an LSD diff. Do your research and decide on which one.

1) M-factory
2) Wave Track
3) M3
4) Quaife

They are much better for winter driving. Unless you track the car, or canyon carve, you probably won't see much of a difference when spiritedly driving the car on normal roads. That's the only drawback.

Thanks for your reply. reading what you say about rarely seeing a bad diff, is there anything else that could be causing the issue of bearings failing very quickly?

[mweisdorfer]

Originally Posted by MF3series

Thanks for your reply. reading what you say about rarely seeing a bad diff, is there anything else that could be causing the issue of bearings failing very quickly?

Ya. I can't believe that many bearings went bad in that short amount of time.

You used full synthetic 75w90 gear oil like red line, Amsoil or Royal Purple?

I would think there might be a 500 mile break in period where you shouldn't run the car real hot.

[Emilime75]

Which bearing failed and was it the same one, every time?

[gbalthrop]

Originally Posted by MF3series

...2010 E91. at c48k miles the diff bearing failed and was changed within a week or so on buying it...It failed again at 56k and 63k and bearing was replaced again both times, each time the bearing noise from the diff starts out only slight and get worse and worse but fine after replacement. Now at 72k miles its gone again.

There are a number of different bearings in the differential. Has the "failed" bearing ALWAYS been the Pinion Shaft or Radial Shaft bearing? Has there always been a "whining" gear noise heard upon over-run or letting off throttle and decelerating without braking? If the bearing in question is an output shaft bearing on either side, a "roaring" noise, more pronounced when the worn side is loaded in a turn, similar to a wheel bearing, would be expected. Please describe the bearing replaced, the sound heard, and conditions at which sound is greatest.

Any bearing in the differential should NOT wear out every 8,000 miles or less. The most likely explanation is improper assembly. That is particularly so if the Pinion Shaft/ Radial Shaft bearing is in question. Here is the TIS procedure for just replacing the SEAL on that shaft, and you get some idea of some of the issues involved in proper assembly and having the correct torque/ position of the nut which properly tensions the pinion gear to prevent whine or improper wear.
https://www.newtis.info/tisv2/a/en/e...-drive/4LWolh0

If the Pinion Shaft nut/ Flange Nut loosens, the pinion gear does NOT mesh with proper load, and whine on deceleration occurs. If corrected in time, NO replacement of anything internal to the differential is required. If that is what you are experiencing, the cause may be improper assembly of the parts shown above.

Please let us know what you find,
George

[Efthreeoh]

It's possible the diff casting is bad. Just find a used differential, which are easily found on the internet for a few hundred dollars at most and replace the whole different with a used one.

[Andystobbs]

Its hard to set up the diff properly when rebuilding it. BMW in the UK do not release any info on how to torque the pinion shaft nut to correctly adjust the crush sleeve. They don't even sell diff parts.

[MF3series]

It always starts as a quite grinding, similar to that of slightly rusted break pads. Noise gets louder the more miles you put on it. The noise increases with speed but never changes under load, braking etc.
Its always been repaired at a Transmission specialist and i believe they have changed the same bearing each time but not sure which one that is. I cant get any more info from them as they are now refusing to work on it (first repair carried out under warranty from private dealer and further 2 repairs under the garage warranty). Now neither want to deal with me or are producing any info on what was completed.

I'm now looking a changing the whole diff.....

[N52bigblock]

Originally Posted by MF3series

It always starts as a quite grinding, similar to that of slightly rusted break pads. Noise gets louder the more miles you put on it. The noise increases with speed but never changes under load, braking etc.
Its always been repaired at a Transmission specialist and i believe they have changed the same bearing each time but not sure which one that is. I cant get any more info from them as they are now refusing to work on it (first repair carried out under warranty from private dealer and further 2 repairs under the garage warranty). Now neither want to deal with me or are producing any info on what was completed.

I'm now looking a changing the whole diff.....

You haven't said what type of engine you have in your car but I'm betting it's a 4 cylinder. Unfortunately the diff in the 4 cylinder and 6 cyl 323i (small type 168) has a big issue with pinion bearings wearing out prematurely. I don't know why but it is very common in the small diff. All the other larger diffs (fitted to 325i, 328i and 330i) seem to be virtually trouble free, which is probably why nobody on here has heard of any issues, as the US didn't get the 4 cyl or 323i. I have rebuilt the diff in my e90 323i, and have had no issues with it after the rebuild.

So it sounds like there is either something wrong with your casing or the shop which rebuilt it doesn't know what they are doing. Why are they only replacing one diff bearing and not all 4? If you are getting a 2nd hand unit my advice would be to make sure it has a warranty, as another thing these small diffs are bad for is wearing out the planetary gears.

In my search for a good set of planetary gears during my rebuild, I had to strip 4 diffs before i found a reasonable set, and even then they were not perfect. All of those diffs had between 100 and 130000 kms, so not much really. So be careful when chosing a 2nd hand unit! I have also driven several low km 4 cyls (60-80000km) and noticed the diffs were noisy. Here is a link to some pictures of my diff bearings etc. My car had 140000km on it.
https://www.e90post.com/forums/showt...php?p=24350755

[MF3series]

4 Cylinder indeed!
Thanks for the help all