Driver's side seat loose and slides back and forth. What's the fix for the seat rails?

Sounds about right for the seatbelt tensioner. At the time that they replace this they will have to remove the seat, so ask them to fix the seat issue as well, since they will be right there. It sounds like a bent or broken stop on the seat rail or perhaps just a loose bolt.

Hi Barron55 I have the same problem but with BOTH seats. Drives me crazy! You would think that an expensive top end sports car from BMW would have better seats . . . more like the z4. Now THOSE ARE SEATS! If it weren't for keeping the car original, I'd go shopping for some z4 seats at scrap yards like yesterday!

Hey Carl I am curently working on a friends seats. BMW knows its a common problem and wanted to sell me the entire steel rails,motor assembly for 600.00 for only one of the two seats. I took it apart and discovered that they used some kind of rubber compound to cushion the stopping points at front and rear stops, and to reduce vibration in the seat. However after a few years the rubber deteriorates to a soft gooey mess and allows for the forward and back slop. I without alot of tearing apart of the rail find a way to repair it so I am going to look for a dealer that will sell me the rails only. That is where the problem exists not in the electrical movement mechanisms. Hope that helps. Later Brian

Here's the solution to your problem... http://www.whalenshiftmachine.com/index.php?main_page=index&cPath=3 The slidey seats are a well known problem with the Z3. The original bushings are made of soft rubber and can't hold the seat in place, but these replacements are made of harder plastic. If you're having the seat belt tensioner replaced, you might get these installed at the same for little to no cash.

There is a repair kit for this seat tracks that go bad. It's a well known problem. Here is a link on the how to and why. http://www.odometergears.com/subpages/seat_rocking_fix.pdf