E34 '91: vibration when accelerating

[Tcdoe]

Hi everyone,

Ever since I bought the car (3 months ago) I've been getting some vibration when accelerating (especially noticeable after wheelspin). Normally this hasn't been too severe and has gone away after a short while. Also when driving slow into sharp bumps I can feel some looseness in the steering. Additionally the car tends to veer a little to the right. Ok, so I've had those problems for a while but I've always forgotten them because they were pretty rare.

But today I changed to my winter tires, and the vibration is pretty bad now.. It now occurs most of the time when accelerating at speeds over 80km/h (~50mp/h). Someone already suggested that my winter tires may not be balanced properly and that it could be related to the transmission (driveshaft joint?), but I don't think so because of the other symptoms (I assume these problems are related) that appear to concern the steering.

So now the problem basically is that the car (feels like mostly the front end) vibrates after accelerating (there's a slight delay after stepping on the gas).
- Pressing the clutch down during the vibration does not affect it at all.
- There's no vibration when rolling in neutral (above 80km/h) and revving the engine.
- Vibration does not appear when braking or driving at a steady speed.
- It usually disappears when I drive steadily...
- ...and vice versa, the vibration get's _really_ rough if I keep my foot planted.
- A slight clunking sound can be heard during the vibration, but I think this is
just because of my aftermarket wheel. At least it sounds as if it's coming from the steering wheel itself.

And now for the million $ question: What could be causing this? Anyone have any similar experiences?

Many thanks in advance!

- Edvin & 535i '91

[JonE]

Try Bruno's site,http://www.bmwe34.net/ for the numerous possibilities that exist for your symptoms. Sometimes it is difficult to get it all sorted out, esp. if there exists more than one possibility. My guess is that you have at least 2 or 3 things going on. Are the rims for the snow tires centered properly on the hubs? Are they properly balanced on the rims? Others should have many ideas on the steering/suspension issues.

[Tcdoe]

Thanks, I'm starting to think that it's the upper control arms/bushings that are broken. Gotta get the front end and wheels checked asap. Anyway, keep those tips coming if you've got 'em. Thanks again.

[Mobius]

All this vibration that changes in intensity based on how close your foot is to the floor is driveline shake. Driveline shake can come from two places: A rotting guibo, or a shot U-join in the driveline.

Guibos (the rubber coupler between the transmission output flange and the front of the driveshaft) aren't too expensive and are pretty straightforward to replace. It's also easy to tell when one has failed, especially one that's making the car shake. It will be obvious when you look at it, I promise.

The E34 driveshaft, however, is kind of a bitch. The U-joints are not serviceable, so if you determine this to be the problem, you'll be stuck paying nearly $400 for a new driveshaft (but, yay! the new one has rebuildable u-joints!).

I've had the (mis)fortune of experiencing the failure of both. The guibo died suddenly and made the car almost undriveable (massive shake and banging noise, which was the guibo trying to take out my shift selector rod). The driveshaft failed slowly and only shook at periods of high torque (most all of first and the top end of 2nd gear) otherwise, you wouldn't know.

None of this could be seen, however as a front-end shake. But, I also can't see a front-end shake intensifying on acceleration, either. I think you have a couple problems.

[Tcdoe]

It really doesn't feel like it's related to the drivetrain, I'm no expert tho, so I might be wrong.

I'm starting to think that the problem lies in the upper control arms, which then is intensified by the lack of hubcentric rings on my steel rims (which come from a E39, which have a larger centre hole). I'll probably have to get E34 rims and replace the thrust arms.



Quoting bmwe34.net: Thrust arms (upper control arms)
Cause the infamous shimmy (50-60 Mph) and severely enhanced brake shimmy. If the bushings had not been tighten under load, they will be damaged. Check the bushings for cracks, jack up the front with the wheel on and shake the wheel to locate the noise.
Use a pray bar under the arm to check ball joint play (they "clunk" when worn). http://www.bmwe34.net/e34main/maintenance/suspension/upper_arm.htm

The car's going to a garage tomorrow, hope they'll get it sorted out. BTW, I also had the wheels rebalanced today, that didn't help.

[JonE]

Sure seems reasonable if the arms had never been replaced with the number of miles the car has. Was it the E39 rims with snows that you just had balanced? If so, they still might not be centering properly to bring you to the point of "shimmy" that you had with the other wheels/tires. I assume they balanced up properly? I have one steel rim/snow tire that I have to carefully line up in order to avoid that "non-centric" situation. If it is not torqued down just right, the car shimmys. Doesn't do it with the regular road wheels/rims. Let us know what the mechanics suggest, ok?

[Tcdoe]

Yeah, the E39 wheels indeed. The balance on the front wheels was perfect, didn't bother paying for the rear wheels as it became apparent that the problem lies elsewhere. I didn't do the work myself but I asked them if they could try to balance them on the wheels, but they said that it's impossible to do that without the hubcentric rims (they really wanted to sell me new rims :( ).. But this isn't the same shop I'm taking the car to tomorrow. I'll keep you posted!

[Tcdoe]

Got the car back from the garage. They didn't do anything to it, just had a look to pinpoint the the problem. They said the driver's side front shock has died completely.. What do you think? I've never had a shock absorber die before so I don't know what it's supposed to feel like, but I'm not entirely convinced that it's the shock(s). And as if that wasn't enough I had a little accident today, will be needing a new foglight and possibly a front bumper :(

[Mobius]

A dead shock will accentuate the effects of a out-of-balance wheel. If you find that you balance the wheels only to alleviate the shaking for a short time, it's likely the shocks are bad.

A failed shock will likely fail in a way in which it no longer dampens small movements, so you wheel is free to bounce around as it feels.

[drum2430]

Check into hubcentric rings to eliminate some of that vibration. My E34 has e39 wheels on it and without the rings I came make a milkshake between 50 and 60MPH.

[Tcdoe]

I thought I'd follow up on this old thread. Getting the hubcentric rings helped A LOT but there was still some shake at around 60mph. I finally got the upper thrust arms changed (with 750 bushings) this week and the shake has now been completely eliminated. To address the issue of the busted shock I've ordered a KW sport suspension kit, should be here in a few weeks.