I have a 1991 W124 car that has a slight vibration coming through the steering wheel and in fact whole chassis when I go over about 75. All I've done to alleviate this so far is to tighten up the steering box, which made the steering much better, but didnt affect this all. Some key points:

- For some reason one of my wheels has a different offset to all of the others, the different offset wheel is on the front.
- I have some new but very cheap tyres, but I had the same problem with my old ones so dont expect balance issues. The new Tyres were fitted and balanced (I saw it being done).
- The car has 130k miles, and I dont think any work as ever been done to the suspension except new shocks all around.

So any suggestions on what could cause this before I start replacing things randomly. Would the steering damper affect this?

different offset? Please explain, also, does the car pull to eaither side?

The steering damper could be the issue or any part of the steering linkage. Could be other suspension components as well but there'd probably be thuds or clunks or other symptoms.

Is your spare of the proper offset?

Sixto
87 300D

I mean a different offset in that one of the wheels sticks further out of the wheel arch than the others, and has to have longer lug bolts to compensate. The car tracks perfectly straight (and will pull either left or right depending on road camber). Unfortunately the spare is a completely different wheel, so have no idea about the offset, this car is a bit messed up (9 previous owners!).

I personally cant see why the different wheel would make a difference, just though I would put it down to check with the experts.

I cant do much to the car now, but when I have time I think I'm just going to take the wheels off and have a good poke around. I've never really replaced anything suspension/steerign wise before, so dont understand it much, but would love to learn.

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1991 W124 250D - 130k Miles

Raise your front end one wheel at a time, and check for any play in the wheel by shaking it side to side, and top to bottom. If you have any play what so ever, then start looking at your lower ball joints, from there you can check your bearings. The way I diagnose these things is in the following order:
1)high speed wheel balancing -did they take off the old weights from the rim, before they re-balanced the tires;
2)shocks - check tires for steps on thread , if tires feel round, press on the shock, it shouldnt bounce more than two times, if it does, its becomming, or is loose, if you have steps in your tire, your shocks are badly worn out.
3)lower ball joints - check for any movement of the whole wheel. Any slack there would point to lower ball joints, or possibly bearings, although bad bearings usually do not cause slack, but rather a whinning noise.
4)damper - remove the damper from one side, and see if you can move the arm, if it moves rather freely, it needs replacement
5)wheel alignment - normally, I get a wheel alignement when I replace the tires, make sure your tire pressure is up to spec, before you go get an alignment

I am not sure how the offset of that one tire is affecting your car's performance, and transmission, but I would replace that rim, to match the other 3. If you get to #5, and the issue is still not resolved, the person doing the wheel alignment should be able to diagnose the issue for you on the spot. Hope this helps

Fantastic, thats of great help. Like I said I have no experience of suspension problems/work at all, so this should be a good lesson, and I have quite a few tools and the will to learn if anything should need replacing.

I think I'm going to keep that rim for now, as in my engineering part of my brain, I cant see why it would be related to the vibration, and the car has no other handling issues. I'll certainly replace it when I have more disposable income.

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1991 W124 250D - 130k Miles