What is the whirring sound in the back?

[earthduzt]

OK I'm back with another question. So the 325 I got runs great and hardly anything wrong with it, had front engine worked on extensivley a couple months ago, but I notice a deep whirring sound coming from the back when driving. I was told it's the hubs and hub spindles that need replacing...does this sound about right? Is there anything else I should be looking at or replacing while the mech is back there? Also, anyone have a round about figure on how much this will cost me to get them replaced, what can I expect to pay? Thanks again and sorry for all the questions, I just like to hear opinions and facts from people who've been there and done that.

[marti5]

It could be the diff...change the oil or one or both of the rear wheel bearings..

What I would do is raise the rear end and check for movement in the rear wheels also give them a spin you may have ridges on the outer edge of the discs/rotors.

[dudehog]

find a bendy road if it gets louder going round a left hand band then it'd the rear o/s and the other side for a right hand bend. if it increases in sound in terms of pitch like your engine does when the rpms go up then i say the diff. a friend had that on his 320i touring. i had that bearing problem about a month ago done now though