I noticed a high frequency whine coming from the rear of my 04 5 series. 47K miles at interstate speed 70mph. It is not loud but once I tuned into it it became a bother. If I let off the gas it would stop. But as soon as I apply gas to keep it at 70 it came back.

Is this cpmmon? does it mean there is a problem?

Have the rear end checked by a professional. Hopefully its nothing serious, but the noise appears with the application of power. When coasting, the input (drive) shaft places very little load on the carrier. The differential will function as normal. However, the application of power places load on the carrier (and planetary gear sets). The differential then has to both perform its function of allowing independant wheel rotation speeds AND act to distrubute power. Fluid loss, gear misalignment, bearing failure, or gear friction can cause various noises, including the whine. 47k and you're still warranted. 50K and you're SOL without an extended warranty if major repairs are needed. Good luck - let us know how it turns out.

There are no bearings in a differential.

Perhaps some Beano would help?? :lol:

Are you sure? :whistle:

You should have left your wife at home :D

On a more serious note, if your diff is whining get it into the shop asap before it goes bang :)

Sigh... :rolleyes: Let me clarify - WHEEL bearing, output shaft bearing (which, in fact, IS attached to the differential - http://home.comcast.net/~matthew.c.s...ut_shaft_4.jpghttp://home.comcast.net/~matthew.c.s...ut_shaft_5.jpg), carrier bearing, etc...

I have had the same whine in my 04 since I got it - that was with 4000 miles on it as a CPO. It now has 40,000 miles on it. The whine has gotten no worse. If your whine is the same one I have, it is very slight - you really have to listen for it- and I only hear it when I am at constant speed. If I let off the gas it goes away and if I step on the gas a little harder, it goes away. It is only very slight when I hold constant speed on the freeway and everything in the car is very quite - no radio, etc.

I have thought about mentioning it when I have the car seviced but I have alway forgotten. I may try to remember to mention it while the car isstill under warranty just to make sure, but it is very very slight. Good luck with whatever you decide to do, and welcome to the forum.

Thanks for clarifying that. Now everyone knows (including me) what the ENTIRE ASSEMBLY or HOUSING looks like on an E60.

I've never dissected a BMW rear diff assy before, but I have done it on Ford's and Chevy's. I'll bet when you open it up the DIFFERENTIAL inside will look something like this:

http://en.wikipedia.org/wiki/Differential_...nical_device%29

or this:

http://auto.howstuffworks.com/differential4.htm

I've never seen any bearings here.

Free beer for everyone :D

Yep :cool: You? :whistle: