The car is a 1997 328I with sport package

Lately as I drive, especially at ~40 MPH, the car begins to make a sound simillar to howling and the vibration is unbareable. It is focused in the rear of the vehicle.

This has been going on for a few weeks now and I just assumed i needed tires and an allignment.

Last night a friend and I swapped the rims and tires on the car and still had the same result.

The tires we removed were feathered and the rear shocks are blown.

We checked all of the wheel bearings by manipulating the rims front to back, but there was no play. We also eliminated the center-line bearing as the same effect is had if the car is in neutral.

Any input would be greatly appreciated.

I would say rear bushings blown? maybe subframe? control arms?

Also,

If I turn slightly to the right, the vibration stops. If I go straight or turn to the left it continues/intensifies.

Thanks,

I would say rear bushings blown? maybe subframe? control arms?

Any advice for a novice on how I would go about diagnosing which one os causing the issue?

I searched and most of the previous threads involve the front of the vehicle. I am fairly certain my issues are coming from the rear.

Thanks.

Well I am certainly a novice also, but I had the exact problem about a week ago when my coilovers were installed...I had the same type of problem, I'd say get a friend with a lift or head to shop to check your bushings and both rear ball joints?

My bill was just under 1000 for both rear ball joints, the front wheel bearings and new poly bushings installed.

To be honest it sounds like a Wheel Bearing, but it also sounds like the Diff. You gotta get it checked soon, because if I am right about either of these and you keep driving like this, it can cause an accident. Good luck.

I'm pretty sure I know what the problem is. Has your car had sex with my car? Because I think my car gave you whatever disease it has. Maybe we both parked next to each other somewhere around here :)?

Anyway, I have the exact same symptoms as you. I've been chasing a rear end vibration for months and still havent found it. My rear tires were cupped on the inside edge, but I never really knew from what, because my shocks werent all that bad (I replaced them anyway).

Your vibration issue definitely sounds like a wheel bearing, especially the part about having the vibration go away when you turn to the side - thats a dead giveaway. Replace the bearing and start from there.

If you want me to listen to it or take a look at your tires I might be able to, but I'm not sure if I'd be able to tell you anything with any certainty.

If you were just talking about noise I might go along with the wheel bearing diagnosis - although bearing noise generally increases as the faulty bearing is loaded on cornering, rather than going away. However, vibration is caused by either balance issues or wheel shimmy (ie, scuffing and hopping due to not travelling directly along the axis of rotation). The cupping of the tyres on the insides suggests the wheel is not tracking true- it is toeing out. This points to worn rear trailing arm bushes or ball-joints. If turning to the right stops the vibration , then look at your right RTAB - as you hook to the right, this wheel is then tracking more closely along its axis of rotation.

If you were just talking about noise I might go along with the wheel bearing diagnosis - although bearing noise generally increases as the faulty bearing is loaded on cornering, rather than going away.

That's exactly whats happenning, maybe it's a combination of a bad bearing coupled with a bushing issue. I went ahead and purchased a set of Bilstein sports along with H&R sport springs. Now on to some control arm bushings, rear shock mounts and whatever else is needed for an inexpensive, yet quality suspension overhaul. Once the new parts are installed, I will purchase new tires and get a full allignment.

Any suggestions on parts and sources would be greatly appreciated