[turbobird14]

Hey guys! I noticed the other day a very quiet whining noise coming from the rear of my car while i was driving. I was close to home when i noticed it so i didnt think much of it. But then the following day when i started driving it got a whole lot louder. I took it to a local European auto shop to have them look at it since the dealer couldnt get me in for over a weak and he said its definitely coming from the rear diff. Has anyone even heard of this or do i get to be the lab rat again?? and at 66,000 miles??? really?

[yakev724]

Drain the fluid, look for shavings. Replace w/ redline 75w90.

Used 335 diffs are cheap, or maybe LSD if you're looking to track the car.

[turbobird14]

would it be easier to replace the whole diff or the gear itself? and if i do have metal shavings... is their any saving the oem gear just by a fluid change?

[sammy_0559]

Originally Posted by turbobird14

would it be easier to replace the whole diff or the gear itself? and if i do have metal shavings... is their any saving the oem gear just by a fluid change?

LSD


http://www.e90post.com/forums/showthread.php?t=663699

[turbobird14]

Whyyyyyy did u have to show me this!!!! Im trying to sell the car!!!!!

[sammy_0559]

Originally Posted by turbobird14

Whyyyyyy did u have to show me this!!!! Im trying to sell the car!!!!!

O lol well keep it an enjoy hahahaaaa

[Surly73]

Well, a couple of comments....

Sometimes crap happens. You might be unlucky and have an abnormal diff failure. If you have faulty components, there is no "at only 66k?" comment you can make... crap happens. Replacing the diff is not a maintenance item and isn't something that everyone should panic about.

That being said - replacing diff fluid *IS* a maintenance item yet it's something BMW has removed from the schedule. There is no such thing as a lifetime fluid anywhere on the car. How many times have you changed the fluid in 66k? I've seen/heard of plenty of cars underfilled from the factory - add that to "lifetime fill" and it's a recipe for disaster.

Also, Mike Miller is on record stating that newer BMW diffs aren't as bullet proof as they used to be. Cheaper bearings, smaller diameter ring gear etc...etc... If nothing else, this is reason not to follow "lifetime fill" habits.

Last, I've read in several places that the E9x diffs often whine a little (perhaps evidence of the cheaper construction). I think mine does it too but it's hard to tell for sure over the loud tires the PO put on the car. A sudden increase in volume is cause for concern, of course.

[DASHOCKER]

amsoil 75w90 is good stuff..

[Surly73]

Originally Posted by DASHOCKER

amsoil 75w90 is good stuff..

That's what I have in my E90 right now. My choices are Redline 75W90 or Amsoil SVG 75W90.

Redline is very high in esters, which have very strong cleaning ability and are excellent for conditioning/cleaning seals (e.g. leak prevention or repair).

Amsoil is, as far as I can tell, high in PAO but the SVG product is EP ("extreme pressure") rated meaning that it contains additives for high stress environments and can actually "heal" worn or pitted metal to a certain degree. The SVG product is also rated for ridiculously long change intervals in "normal" operation, although anyone who really cars about their car should perform all maintenance according to the "severe" schedule IMO.

On the other hand, redline smells far stronger of phosphorous and sulphur so, although it doesn't carry an EP rating, I have no doubts about it's abilities.


From http://www.syntheticlubes.com/extrem..._gear_oil.html:

Additive Performance
AMSOIL SG Oils are fully formulated with sulphur/phosphorous extreme pressure additives, antioxidants, rust inhibitors, and anti-foam agents. The SG Oil's thermally stable, extreme-pressure additive system forms a hard, iron-sulfide coating on metal components. This iron-sulfide coating prevents metal to metal contact under boundary lubrication conditions, reduces friction and protects components against shock loading and wear. The anti-oxidants increase the oxidation resistance of the synthetic base oils for long, clean lubricant performance. These oils protect against rust from water or process contaminants and prevent foaming, ensuring proper lubrication.

[bumere90]

go with redline

[osukf09]

I had my rear diff go out around 55k. Heard the whining noise, had an occasional rough shift that felt like the tranny slipping, took it into the dealer. Luckily I was covered under CPO warranty..

[turbobird14]

So i see all the comments about the different types of diff fluid, so are you guys suggesting that replacing the diff fluid might cure the problem?

[Surly73]

Originally Posted by turbobird14

So i see all the comments about the different types of diff fluid, so are you guys suggesting that replacing the diff fluid might cure the problem?

Maybe, maybe not, but it's a pretty cheap thing to try...

Changing all fluids regularly will help to prevent problems, which is the point of the fluid-related commentary.

[fun2drive]

It makes almost no sense to replace the ring and pinion compared to the replacing the diff. You don't have to do much replacing the diff but replacement of the ring and pinion is not something that can be done without setting many parameters and then button it up, preload, gearlash, etc are all required and someone that is good at it too is important...
Much cheapier to pop the old one out and pop a serviceable in.
I hope the diff lubes work out for you because 66K miles is way out of line...

[turbobird14]

I agree, I understand that every vehicle is different and that certain parts will wear premature. But this is a non-electrical, 100% Mechanical part that has been spec'd the exact same way every other diff has been from the factory. I dont know what would cause this besides not changing the fluid. But like BMW states, its a non-needed service. And if its from drivability, i dont beat on the car or drive it hard at all. Maybe thats the problem haha

[Surly73]

Originally Posted by turbobird14

I agree, I understand that every vehicle is different and that certain parts will wear premature. But this is a non-electrical, 100% Mechanical part that has been spec'd the exact same way every other diff has been from the factory. I dont know what would cause this besides not changing the fluid. But like BMW states, its a non-needed service. And if its from drivability, i dont beat on the car or drive it hard at all. Maybe thats the problem haha

See other posts: sometimes sh!t happens. If it's not all over the forums it's not a chronic defect.

Change your fluid now and see if it helps. Pay attention to whether the level seems to be low and just how much glitter comes out with the fluid. It's too bad the E90 doesn't have a drain plug - getting most of the heavier wear materials out via suction pump will be difficult.

[turbobird14]

Ok ordered the redline! Ill update as soon as it comes in and is changed

[e90will]

Originally Posted by turbobird14

Ok ordered the redline! Ill update as soon as it comes in and is changed

Can't go wrong with redline. I've changed my diff fluid twice with this brand, one at 60K and the second at 120K. Diff is fine so far and redline is what i will only use.