Anybody with an E34 55mph wheel shimmy? These are things I did on my '95 and now am very happy

1) If you have original tires/wheels – are they balanced and “round”? Have you swapped them front to back to verify it is not the tires/wheels?
2) If you have aftermarket wheels – do they have needed adapters so that they are hub centric?
3) If you have shimmy only while braking – check your rotors for out of roundness

An alignment won’t hurt to verify that things are in good working order (although only front toe in is adjustable) front and back.

Okay, now for the fixes (and I don’t take credit for these, just that I have been through this and now drive a 95 that feels awesome):

1) Appropriately jack up the car on one side (I suggest passenger) and grab the raised front wheel laterally (3:00 and 9:00) and try to rock it in and out alternatively (pull with one hand, push with other). Best if someone holds the steering wheel to prevent motion there. If there is slop in the wheel movement, you know you have an issue. In my case I could hear something up front and then see about 1/8” of free lateral (like a tie rod was shot) motion on the passenger wheel. I should point out that I had new control arms, M5 bushings, tie rod ends and new center/drag link and I knew my idler was fine when I saw this motion. Look for joint boots that are cracked – this is a sure sign that you will have ball joint problems in the future. Any noted slop here could be wheel bearings (I have not replaced any of these on this car) or joints/bushings in the front end. This is the hard part – you may need to temporarily remove some joints to see where the slop or bad joint is located. If nothing looks obvious, you may want to shoot to step 2 as it may get your front end 55mph wobble “good enough”. Don't forget to check your bushings - they may be completely shot although I could not detect this without removing them. I suggest Lemforder, they seem to work unless you really like to experiment and/or swap out front end parts.

2) Tighten the collar nut on the steering column! I did this last and really regret not doing it sooner as it is so simple and was a fairly large contributor to the problem. It should be the first thing after careful inspection of the front end for obvious problems as noted in step 1. Use this time to visually inspect that your flexible coupler (close to column) is in good condition and bolts are present. Tightening the collar nut too much will jam the column extension motor. I tightened mine by removing the panels so that I could get full access to the collar which is a bit of a pain but worth the time it takes. It would be a great time to replace that brake switch that you know is going to fail. It takes about 30 min if you take your time to take the panels off and do the adjustment. By the way, the symptom of a loose nut is that there is a non-directional clunking sound (and mine was obvious) when moving the steering wheel back and forth lightly in the “slop” or deadband (friction force only) zone. Refer to http://www.bmwe34.net/Wiki/tiki-inde...=Steering+play

3) Steering box adjustment – I say this with much trepidation as although it can solve some backlash problems, you do take risk that you may cause castering to be degraded and possibly even cause damage to the box. There is an adjustment on the top (17mm lock nut if I recall correctly) with an Allen center adjustment. I only moved mine about 90 deg (CW) and it made a noticeable difference. Again warning, tightening too much could make the car not caster properly (wheel centering) or cause excessive friction or failure of the bearings. Again the above link has some description of this as well. There are more links here but this was the quickest I could find.

Enjoy,
Scott