How to fix them (archive)

I'd been plagued with a slight movement in the driver's seat ever since I bought my 97 2.8. Not much (1/4 inch) and only under hard acceleration. Made the car feel cheap. The dealer took a look at it and concluded the movement was, of course, normal. It started to drive me crazy. I finally resorted to taping together two 2x4's to form a T which I placed in back of my seat.

Pushing the seat back stabilized it enough so the movement stopped, but it's quite a kludge in my $40K car. A couple of months ago, I went back to my dealer to have the hard-top installed and showed them my solution to the problem. I then asked them for the address of BMW engineering so I could send a couple of pictures to the boys back in Munich. After seeing my ingenious solution they agreed to take a second look at the problem and offered to replace the seat rails. They ordered the rails but while replacing them, they discovered the real cause of the problem - aparently, two clips were broken and this allowed the seat to shift slightly under acceleration. They ordered the clips (took an extra day, but I had their 328 loaner, so it was no hardship) and put everything together.

Here's the part numbers:

52-10-8-401-291 Seat Rail (claimed to be unnecessary)
52-10-8-407-659 Clip (replaced 2 of them)

Things were good for a while, until I noticed another slight sensation - a backwards/forwards "rocking" movement. I took it back to BMW who said they would "tighten the seats as best they could", but they said this was a chronic problem in the 3 and 7 series cars. When I got the car back, it was better, but still rocking.

Being an engineer, I, of course, took some time to debug the problem. I found that the place that was rocking was where the entire mechanism joined to the seats. Upon closer examination, I found something interesting on the left hand side - a flash of copper:

There was no corresponding copper on the other side, so I tried to see if it would come out. Sure enough, it was a penny! It looks like someone had jammed it in there to "tighten up" the seat. The funny thing is, it seemed to work, so I shoved another penny into the other side and the rocking stopped!

I'm not sure what the long-term effect of this "kludge" is, so I can't recommend it for more than an interim solution, but I've been "pennied up" for about a year now.

(Press the pictures for a closer look.)

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