Vibration in rear of car - running out of ideas

[Derek A.]

I have read a lot of previous posts about seat-of-the-pants vibration - without seeing a whole lot of resolution.

From 45-65 mph I have a vibration. I can see the passenger seat moving, I can feel it in the seat of my pants. There is no shimmy in the wheel. At 85 mph the car is smooth as silk. Applying the brakes does not make a difference.

The following has been done.

1. Drive shaft replaced w/new center bearing
2. New trans mounts
3. Balanced rear tires then swapped out rear tires - no change
4. Rebuilt both rear calipers - driver side was sticky.
5. Ran car on hoist - no obvious shakes.

I have no noises or other problems. Cars drives great. I just have this wicked vibration. Any ideas on what else to pursue?

Derek.-

[rob101]

could be the dog bones (rear pittman arms thats the only idea in my mind.

[Derek A.]

Dogbones were replaced last year - they are in good shape.
Rear subframe bushings year before.

[Zeuk in Oz]

When were your thrust arm bushings last changed ?

[Kobe Diesel]

Check the CV joints on the drive shafts? if the rubber boots are worn and all the grease has flung out, well the joint is shot, and this can give you vibration.

It's a long shot but also check the differential mount.

[wingman]

What do your tyres look like? Are they balanced and are your wheels completely round? Sounds silly but usually the most basic things are overlooked.

[Derek A.]

I would think a thrust arm problem would manifest itself in the front end? I had 750 bushings put in a couple years ago.

I thought about the rear cv joints. The boots are all intact.

I swapped out different wheels and tires - and it didn't change. So its not a wheel tire issue.

The only possible caviat to the whole thing is that I have concentrated efforts on the rear as the steering wheel is rock solid. I can't imagine that it would be a problem in the front.

[stargazer_61]

Have you checked your rear control arm bushings? While diagnosing my vibration issue, the ones on the left side appeared cracked on my 540i.

[Derek A.]

We ran the car on the hoist and nothing jumped out. So its possible its a control arm issue. But it doesn't happen all the time and varies in its degree. I was really thinking wheel and tire - but I swapped out wheels/tires and it didn't make a different.

Generally with a bushing failure - I would thing that there would be a pull or a clunking noise.

[632 Regal]

out of round tires. I dont care that you swapped them out, probably have another set of out of roundies.

[shuriken]

Rear wheel bearings? Or warped rear discs? Can you warp rear discs? Just a thought.

[Derek A.]

Ran the car on the hoist today. You can feel it with the car in the air. The net effect is that the vibratio nis present at the wheels. If you take the wheels off and run the car - you can still feel a little bit of it. I am guessing a half shaft problem.

Anyone had similar half shaft experince ?

[Up North Bimmer]

I had the same problem with my 525it (vibration severe!), looked at many mechanical culprits, got new tires, then when I got bad rear wheel bearing replaced, the vibration went away.

[Derek A.]

I wouldn't characterize the vibration as severe - its more of an annoyance. We listend to wheel bearings at speed with the car on the hoist. They were pretty quiet.

[shuriken]

It sounds like the problem is when the car is loaded under body weight, as on hoists the wheels are 'loose'. Hope you find the fault without throwing to much dosh at it.

[Bellicose Right Winger]

I'm interested since my '00 528iTM w/66k, Sport, self-levelling and 17" wheels has a minor but very annoying RR vibration from 55-70mph. Mine completely disappears at 75mph. It's road surface dependant and reducing tire pressures to 30psi helps a lot, but doesn't eliminate it. Like yours I can feel it running on the floor jack, and it's reduced, but not eliminated when wheel is removed. Putting spare on reduces it also. Putting suspect tire/wheel on front doesn't create any problems there so I believe wheel/tire are ok since front ends are more sensitive. RR shock seems a little weak, but $460 for 2 shocks and mounts make it an expensive test.

In your case, if vibration was reduced to "a little bit of it" when you remove wheels then the wheels would seem to be a major contributor to the problem. If problem were half-shafts I would expect vibration to be unchanged when you remove wheels.

Although I doubt it's the half-shafts, can you remove them one at a time and repeat test?

Paul Shovestul









Ran the car on the hoist today. You can feel it with the car in the air. The net effect is that the vibratio nis present at the wheels. If you take the wheels off and run the car - you can still feel a little bit of it. I am guessing a half shaft problem.

Anyone had similar half shaft experince ?

[Derek A.]

If the problem is the half shaft - by removing the wheels I have taken some of the interia off the spin. The wheels I think are taking whatever motion is being creating and amplifiing it. I am thinking I might try and source a set of different half shafts and see if that helps. with the shafts off I can make a better assestment if the wheel bearing situation.

[mamilapon]

Got the same sort of vibration at the back but the mrs asked not to touched a thing!!!

[trumpetr]

out of round tires. I dont care that you swapped them out, probably have another set of out of roundies.

I agree. Usually a shimmy that you can 'drive out of', past 75mph, is usually a tire or wheel issue- bad tire,,wrong hubcentric rings,,bad wheel, balance off.
Since you can drive out of it, id be thinking the simple stuff, like a egg tire, or a wrong centric ring, or maybe you threw a wheel weight.

[Derek A.]

I balanced the tires twice and they came out.

Interesting enough this morning - (the car sat out last night and it waspretty cool here in Michigan) - I was able to get the car up to speed quickly and there was no vibration at that speed. So does that confirm that its a very squirly tire issue ? Or is it possible that there is another temperature sensitive problem ?

[632 Regal]

i think your on to something now.
definetly sounds tire related, remember all the problems I had when I first got my car? 50 trips to discunt tire, 2 sets of tires and never got it smooth until I bought them sempirit cheapie snow tires that smoothed out my world. Now I have the falken 512s and those are pretty round but not as nice as the snows...


I balanced the tires twice and they came out.

you can balance a square tire perfect but you will still feel it bounce on the square corners.

Interesting enough this morning - (the car sat out last night and it waspretty cool here in Michigan) - I was able to get the car up to speed quickly and there was no vibration at that speed. So does that confirm that its a very squirly tire issue ? Or is it possible that there is another temperature sensitive problem ?