stumped on 50-60mph shimmy

[Shauhin]

at the range of 40-50mph I frequently get a very nasty vibration through my steering wheel and then it spreads to the whole car shaking. it only occurs when i am driving straight get in that speed range. I can only use the word VIOLENT to describe how bad it shakes up my car. I have to jerk the steering wheel back and forth to get rid of it. when moving

I already had the shocks changed, wheels balanced and aligned, thrust arm bushings replaced with 740il bushings, and tie rods tightened.

Anyone have any suggestions or advise please? it does not pose me as dangerous to drive it; its just that if im on a city street and get a 45mph shake, i have to bounce aroudn on the wheel just to get rid of it. on freeway high speeds the car feels solid as ever.


Thanks in advance,

Shauhin

[TimGinCentralNJ]

Hi Shauhin-

I've had some experience with a shimmy on various E28's, and my last E34, but the only time I ever experienced what you've described occurred on my last E28 as the result of my left front brake caliper beginning to seize on me. It began after the first panic-stop I'd ever done in the car, and although you couldn't even tell the caliper was grabbing (meaning, there was no pull to the right, the car handled perfectly), it was just enough to create bone-jarring cavitations around 40-50. Sometimes I could jerk the wheel enough to free it, but not always.

Not saying you should disregard what the other have said her, only want to add this as a possibility.

Hope this helps,
Tim G.
'91 535iM

at the range of 40-50mph I frequently get a very nasty vibration through my steering wheel and then it spreads to the whole car shaking. it only occurs when i am driving straight get in that speed range. I can only use the word VIOLENT to describe how bad it shakes up my car. I have to jerk the steering wheel back and forth to get rid of it. when moving

I already had the shocks changed, wheels balanced and aligned, thrust arm bushings replaced with 740il bushings, and tie rods tightened.

Anyone have any suggestions or advise please? it does not pose me as dangerous to drive it; its just that if im on a city street and get a 45mph shake, i have to bounce aroudn on the wheel just to get rid of it. on freeway high speeds the car feels solid as ever.


Thanks in advance,

Shauhin

[jplacson]

so a shimmy could also be caused by the brakes? (if the suspension turns out to be ok)

[TimGinCentralNJ]

...adding the slightest resistance to just one of your front wheels is enough to alter your suspension geometry, 'bringing to light' even the slightest amount of play in the form of a shimmy. I'd never have believed it either had I not been through it myself

All I'm saying is, if you've checked/repl'd everything else, do yourself a favor and check out your calipers to ensure they're releasing. Look for unevenly worn or unevenly "hot" rotors up front, and just make sure both front wheels spin freely. It's a cheap test, and one often overlooked IMHO.

Tim G.

so a shimmy could also be caused by the brakes? (if the suspension turns out to be ok)

[MBXB]

JP,

Bad brake rotors can cause shimmy.
I had a new but not balanced rotor drive me and my tech nuts.
He didn't believe me at first. Got a free replacement.

Ramon

so a shimmy could also be caused by the brakes? (if the suspension turns out to be ok)

[jplacson]

Thanks! I also want to mention that I have a rear "clunk" when cornering. I'm trying to see if my shimmy might be tied into this as well... what could cause the clunk? Rear shocks? Or the subframe bushings/mounts? This only happens while cornering, not accelerating.