Lately, when I'm going anything over 10 mph the back end of my 528e ('84) is wobbling from side to side. It makes for a rather bumpy ride. Could this be caused by bad wheel bearings? A lose sway bar? Shocks going ? I love my car, but I'm no mechanic. I'm going to bring it in, but would like some "warning" advice or suggestions so I don't get taken by my mechanic. Thanks!

what speed is it vibrating? the rear might not vibrate if the wheels are out of balance, check that first, how bad is the vibration, also check your u joints in the driveshaft, if the vibration gets worse and worse then it can be your driveshaft.

Ok,
So if I take it in to have the wheels balanced and that's not the problem, will I need to get the entire driveshaft replaced if it's the u joints? And is there a way to know that's the problem before going through that? I can't completely figure out where the vibration is coming from. I think it's coming from the back left side of the car, though I could be wrong. I also can't decide if the motion is left to right or just up and down. What I really need to do is have someone else drive the car and follow behind to see if I can tell better from there. The car rides really bumpy in the back end when I'm accelerating up to speed, especially when the car is cold and is still warming up.

Thanks for the help. I wish I could do more of this stuff myself, but I'm living in an apartment outside of Chicago right now and don't have a garage where I can work on it, so I'm stuck with mechanics for now. Is there anything that I (an average joe) can do to check the u joints myself if I can get it up on blocks before bringing it in to a mechanic?

Ok,
So I figured it out, for anyone who's interested, I figured out what was up. I finally took off the rear tires which are two years old and figured out that the bands must have seperated in each, because they were completely sloped and caved. Anyway, it looks like two new tired should fix it. Thanks for all your help!