Rear end shaking is getting worse

[hooRAH]

So my car has a rear end shake thats been very, very slowly getting worse. The shaking is two parts - one is a random jiggle that until recently has been very hard to differentiate from just random bumps in the road. The only way to describe it is that its not smooth. Sort of feels like what a loose RSM would feel like. My car used to be more quiet and smooth than my girlfriends toyota camry, now its the other way around. At first, I bought the explanation that it was a sportier car with 17" wheels and it was normal, but not any more. Its definitely shaking enough that theres something noticeably wrong.

The other part is a harmonic vibration at high speeds. The tires are new, this did not help the vibration. I've had the wheels balanced over and over and over again. I recently took the car in to my independant mechanic who looked over everything in the drivetrain. He saw no play in the driveshaft or the ujoints. Flex disc and CSB look great, no cracks. CV axles look good. Rear diff bushing had a crack in it, but thats been fixed. When we spun the wheels in the air, he said it looked like both of the wheels (one worse than the other) had a bit of up and down play in it, so he recommended a road force balance. I paid for the road force balance (although I didnt see the shop do it or get any readouts, as they had to outsource the roadforce balancing to a local shop) and picked up the car. For the first 2 days, the harmonic vibration was slightly better, but the jiggle in the rear was still there. Both the mechanic and I have checked the rear wheels for play over and over again, and I can't feel any play in the bearings.

Today, it feels much worse. The jiggle is enough to rattle the coins in the cupholder and the harmonic vibration is back worse than ever. Although we couldn't find any play, I'm thinking that its got to be the bearings. I have a woomp woomp woomp /whirring noise up to about 45mph that everyone tells me is tire noise, but I don't buy it. The jiggle, the vibration, and the whirring on nearly new tires, even when switching to the spare, is too much of a coincidence, I think. I've also tried driving at speed while slowly changing lanes on a solid painted line, and the noise doesn't change. I REALLY don't think its the tires.

Theres no change when I swing the car side to side, but I've been told that E36/46 bearings don't usually change noises when turning like the fronts do. Does this combination of symptoms sound familiar to anyone?

I'm running out of things to test/replace.

[hooRAH]

Short version:

Rear end jiggling like running over rough pavement, high speed vibration getting worse
Mechanic (and myself) saw a bit of up/down shaking in wheels (one worse than other) when spinning wheels in air.
balanced new tires over and over and over, including roadforce balance
replaced tire with spare tire, no diff
no play in bearings that I can tell by lifting wheel and tugging
no play in driveline
does not change sound when turning
woomp woomp woomp /whirling noise at 10-45mph
My mother has a very bad bearing in the front of her jeep that I just found but apparently has been bad for months. It does not sound like that bearing.
Cant rotate tires (staggered)
flex disc/csb/diff mount all good
replaced all 4 shocks/RSMs/RTABs
I'm going crazy.

I think the fact that there is play in the wheel when running combined with the humming noise HAS to point to a wheel bearing. I just don't want to waste $650 being wrong about this.

[hooRAH]

No one? Well, Im planning on doing the 2 rear bearings at the beginning of next week. I've run out of things to test or replace.

[nathancarter]

... wish I had something useful to contribute.

[Chronic2112]

I got tired before I reached the end of your post, so I'm not sure if you know this but, E46's are notorious for having an issue with the rear subframe.

That is what this sounds like to me. You can jack it up and look at the rear-end. (there are pictures posted on here and other websites of the issue)

I had BMW fix mine 2 times over 6 years, and then finally had TMS weld additional support to permanently correct the issue. (see turnermotorsport.com)

[hooRAH]

... wish I had something useful to contribute.

Thanks, I appreciate the bump. Think I got it figured out now.

[hooRAH]

I got tired before I reached the end of your post, so I'm not sure if you know this but, E46's are notorious for having an issue with the rear subframe.

That is what this sounds like to me. You can jack it up and look at the rear-end. (there are pictures posted on here and other websites of the issue)

I had BMW fix mine 2 times over 6 years, and then finally had TMS weld additional support to permanently correct the issue. (see turnermotorsport.com)

I appreciate the response, sorry the original post was so long. I put the short version after it, but you're right, it was too long. I had already suspected the subframe and checked the car over and over again, I don't see any tears.

I took it to another shop this morning and we found the bad bearings by lifting the car and shaking the wheel. The bearing noises have gotten much worse in the last 2 days, so it became obvious. Yesterday coming home it felt like I was driving on either a flat tire or a loose rim it was so bad. They're replacing both bearings today. I suppose I was just unlucky that the first shop didn't find it.

[nathancarter]

Update? Did the new bearings fix it?

[hooRAH]

Not quite. I had both bearings replaced, and it seems to be better, but not completely. Its very difficult to tell because the severity can vary much, especially with temperature. The day before I got the bearings replaced, it felt like I was driving on a flat tire.

Anyway, the rear feels more planted and less 'jiggly', but the vibration and some of the wobble still persists.

When the shop replaced the bearings, they said they were having trouble getting the wheel to sit flush on the hub because the bore was all messed up. They grinded down the edge to get the wheel to fit on there right, but didn't have any explanation as to why the hub was like that, other than maybe I had hit something (I hate it when shops say that). I suppose it could have been hit before I owned the car, but it never vibrated before.

Anyway, after I got the bearings done the vibration was still pretty bad if not worse than originally. So I lifted the rear of the car again, this time one side at a time. T he vibration is definitely coming from the drivers side rear. I immediately swapped the wheel with the spare and tested again, and the vibration is still there when spinning the wheel in the air, so its got to be in that hub.

[hooRAH]

I split up the posts since mine get too long.

I drove around for a day on the spare wheel (which vibrated the same as the regular wheel in the air), and the vibration was much, much less pronounced, although I could still find it if I was looking for it.

So, I put the regular wheel back on very, very carefully. I polished the back of the wheel, the wheel center, the brake disc, and the hub bore with a wire wheel. Then, I wrapped the hub with a ring of electrical tape (trick I see people with non-hubcentric wheels use). Then, I mounted the wheel and tightened all the lug nuts by hand (no wrench, just the socket) very slowly and constantly rotating the wheel to get it as perfectly center as I possibly could.

With my perfectly mounted wheel, the vibration persists, but is about 50% of what it used to be. I talked to the shop about it, and they've agreed to replace the hub (for I HOPE to be just the cost of the hub without additional labor).

If that doesn't cure it 100%, the only thing left is on-the-car balancing. After that, I give up.

[Twright]

Put the rear tires/wheels on the front and the fronts on the rear. If that changes your vibration to the front, you've got one or two bad wheels/tires.

[hooRAH]

Put the rear tires/wheels on the front and the fronts on the rear. If that changes your vibration to the front, you've got one or two bad wheels/tires.

Cant, they're staggered. But thanks for the suggestion.

[Chronic2112]

Sounds like what I went through on my winter set of wheels...tracking down a gremlin...When I got my new wheels all my vibration went away.

Good luck.

[TopasBlau46]

actually, IIRC, the only E46s that for the majority, had issues with the rear subframe, were the pre-facelifted models, particularly the 323 and 328

not saying that isn't the case, but just thought i'd point that out!

[hooRAH]

I've already checked the rear subframe a dozen times, I'm 100% sure that the problems are not coming from something like this. Its definitely in that drivers side rear wheel assembly.

[daveo11]

Did you ever figure out what it was, causing the vibration? I'm having the same problem?

[dworthy]

Gee reviving a 9 year old thread where the OP I am sure doesn't frequent here much.

I would start with the balance of the tires first, then look at the bushings, then the rims themselves and lastly the bearing.