Should I keep it - BMW Says Rear Diff Needs To Be Replaced

Originally Posted by X3emist

Actually I get a clunk at times specifically if I go to take off from a stop and then let off the gas abruptly, same when backing up and letting off gas to stop and reverse direction. It seems the deceleration when the vehicle is in 2nd or 3rd gear causes the clunk.

I'd guess that is when the transfer case is "kicking in". I bet you'd also get it if you were in a snow/ice slipping situation where power had to be transferred.

Update - Finally ALL the clunking is gone! Took it to this import specialty shop that my cousin recommended for one last check and opinion before we replace the rear diff. The tech there said that the rear diff sounds just fine, but the transfer case was noisy. They checked the oil and it was pitch black. They flushed and put in some oil of there's with some modifiers. Drives great now, but he said there may be damage to the transfer case. All said and done It just amazes (and scares) me that all the other shops including Knauz or BMW itself DID NOT see the miss matched wheels/tires or even looked that the transfer case as the problem. It took a total of 5 shops to figure this thing out. And it was my cousins shop which is a body shop that told me the wheels were on wrong and gave me the hookup at this specialty shop they work with.

For anyone else having this problem here's what I had done:

1 - Transmission Software Update (which I don't think really made a difference other than my mpg going down)
2 - Engine coils (Made no difference)
3 - Differential oil flush
4 - Tires were miss matched and rotated back to factory specs (Made a huge difference)
5 - Transfer Case oil flush (seems to have eliminated the problem)

Originally Posted by Moon the Loon

Update - Finally ALL the clunking is gone! Took it to this import specialty shop that my cousin recommended for one last check and opinion before we replace the rear diff. The tech there said that the rear diff sounds just fine, but the transfer case was noisy. They checked the oil and it was pitch black. They flushed and put in some oil of there's with some modifiers. Drives great now, but he said there may be damage to the transfer case. All said and done It just amazes (and scares) me that all the other shops including Knauz or BMW itself DID NOT see the miss matched wheels/tires or even looked that the transfer case as the problem. It took a total of 5 shops to figure this thing out. And it was my cousins shop which is a body shop that told me the wheels were on wrong and gave me the hookup at this specialty shop they work with.

For anyone else having this problem here's what I had done:

1 - Transmission Software Update (which I don't think really made a difference other than my mpg going down)
2 - Engine coils (Made no difference)
3 - Differential oil flush
4 - Tires were miss matched and rotated back to factory specs (Made a huge difference)
5 - Transfer Case oil flush (seems to have eliminated the problem)

Glad to hear the problem's solved, what a pain to go through all those steps.

The consensus here has been that only official BMW transfer case fluid should be used (and it's very expensive!). It's the only fluid where people don't argue and substitute non-BMW products. So I'll be real curious what your experience is over time using non-BMW fluid.

Wan't it I who turned you on to the tire issue, just sayin!!

Originally Posted by Moon the Loon

Update - Finally ALL the clunking is gone! Took it to this import specialty shop that my cousin recommended for one last check and opinion before we replace the rear diff. The tech there said that the rear diff sounds just fine, but the transfer case was noisy. They checked the oil and it was pitch black. They flushed and put in some oil of there's with some modifiers. Drives great now, but he said there may be damage to the transfer case. All said and done It just amazes (and scares) me that all the other shops including Knauz or BMW itself DID NOT see the miss matched wheels/tires or even looked that the transfer case as the problem. It took a total of 5 shops to figure this thing out. And it was my cousins shop which is a body shop that told me the wheels were on wrong and gave me the hookup at this specialty shop they work with.

For anyone else having this problem here's what I had done:

1 - Transmission Software Update (which I don't think really made a difference other than my mpg going down)
2 - Engine coils (Made no difference)
3 - Differential oil flush
4 - Tires were miss matched and rotated back to factory specs (Made a huge difference)
5 - Transfer Case oil flush (seems to have eliminated the problem)

Wan't it I who turned you on to the tire issue, just sayin!!

Steely eyed missile man X3emist

And thanks for the suggestions and help everyone.

Update on the Transfer Case oil - they said they used BG synchroshift with a friction Modifier. So far its been great, smooth as can be, but I'm a little worried now cause everyone is saying to only use BMW oil for the Transfer Case?

Originally Posted by Moon the Loon

Update on the Transfer Case oil - they said they used BG synchroshift with a friction Modifier. So far its been great, smooth as can be, but I'm a little worried now cause everyone is saying to only use BMW oil for the Transfer Case?

Well you can be the first to tell us if "Using BMW transfer case ONLY" is really the verdict

Keep us posted in a couple thousand miles

Why would you take a risk and NOT use BMW fluid? They probably recommended this as the BMW fluid is hard to come by unless you buy in bulk drum form.

You could get a bottle of transfer case fluid for $30-50 and do it yourself

Originally Posted by Moon the Loon

- they said they used BG synchroshift with a friction Modifier. So far its been great, smooth as can be, ......

That appears to be a 75W90 gear oil primarily intended for manual transmissions.

Not sure if there is any synchronizing going on in the transfer case, but I will defer to the engineers among us:

http://www.awdwiki.com/images/bmw-xd...nsfer-case.jpg

Stylized picture, of course, and I don't see any chain which I thought there was.

I suppose any hydraulic fluid can function in a transfer case, and some applications use 5W30 engine oil.

But the dependency on the multi-plate clutch to deliver the xDrive interventions, via the actuator motor, is probably why BMW specified a unique fluid.

As the actuator somehow measures varying wet clutch plate resistance and relays that back to the xDrive processor, I think the weight or viscosity of the fluid might be critical.

I don't fully buy into registering a fluid change through dealer programming so that wear values can be reset, but with a non-standard fluid in there, it would be redundant for sure.

Maybe find some empty parking lot with loose sand or gravel on it and check whether all the expected interventions occur smoothly?

If they don't, that would be the clincher for changing it out ASAP.

If everything works as expected, that import specialty shop may be smarter than the BMW engineers.

Maybe find some empty parking lot with loose sand or gravel on it and check whether all the expected interventions occur smoothly?

So test if the awd is distributing to all the wheels evenly is what you're saying? Thanks for the info by the way, sure sound like an engineer to me

1- You can not buy a bottle of BMW transfer case fluid anywhere, it does not exist. Dealers have it in bulk and some might be persuaded to sell you a liter.

2- You can not buy it for $30-$40, it will be more like $90/liter. Yep, you read that right- for 1 liter.

3- Enough stress has been placed on your T-case from the mismatched tires. Do yourself a big big favor, take it to a BMW dealer and pay them $200 to change it again and put the proper stuff in it. Quick!!

4-Don't screw around with testing it, it is the wrong fluid by a long long shot. Get it changed!! You ignore this at your own risk and expense and you won't like the outcome. I highly doubt your guys are smarter than BMW engineers and probably have very little experience with these transfer cases. Being an "import" shop in no way specifically qualifies them to work on BMW's. They need to specialize in BMW's and have factory trained mechanics working there.

I am not talking down to anyone but BMW's are very particular about what you put in them from fuel to diff fluid and coolant. It makes zero sense to try and shave $10 off your repair bill and use something that is not specified for it. It is just like changing your oil on a much more rigorous schedule than BMW stipulates, it is cheap insurance from my perspective.

Originally Posted by X3emist

1- You can not buy a bottle of BMW transfer case fluid anywhere, it does not exist. Dealers have it in bulk and some might be persuaded to sell you a liter or whatever the proper quantity is.

2- You can not buy it for $30-$40, it will be more like $90. Yep, you read that right- for 1 liter.

3- Enough stress has been placed on your T-case from the mismatched tires. Do yourself a big big favor, take it to a BMW dealer and pay them $200 to change it again and put the proper stuff in it. Quick!!

I am not talking down to anyone but BMW's are very particular about what you put in them from fuel to diff fluid and coolant. It makes zero sense to try and shave $10 off your repair bill and use something that is not specified for it. It is just like changing your oil on a much more rigorous schedule than BMW stipulates, it is cheap insurance from my perspective.

Got mine for $30 It was off classified though.
I've seen a liter bottle on ECS for $62 (http://www.ecstuning.com/BMW-E83-X3-...ase/ES2515453/) That comes with 2 washers and new bolts

http://www.ecstuning.com/Search/83220397244/ES197388/

http://www.rmeuropean.com/Part-Numbe..._E095124A.aspx

http://www.bavauto.com/fland.asp?par...00%20397%20244

I never bothered looking, I took it off this forum somewhere that you could not purchase it, that'll teach me

Originally Posted by Supercourse

http://www.ecstuning.com/Search/83220397244/ES197388/

http://www.rmeuropean.com/Part-Numbe..._E095124A.aspx

http://www.bavauto.com/fland.asp?par...00%20397%20244

its the transmission fluid you cannot purchase, most BMW dealers carry the x-drive fluid, cost about $50 last time I bought it.

I can now confirm that replacing the transfer case fluid eliminated all clunking symptoms.
The fluid was black and had small and had a couple of metal shavings. I think it took like 500km for the fluid to do its magic.
The job is fairly easy to do as well.

no cookie for you x3emist

Aww come on I get one for pointing him to the tcase don't I, the dealer was going to rip him one for a diff

*hands you cookie*