1998 BMW Z3 Seats loose

Tiny
HOLLY223
  • MEMBER
  • 1998 BMW Z3
  • 6 CYL
  • 2WD
  • MANUAL
  • 20,500 MILES
When we bought the car 2 years ago, the passenger seat would jerk forward/backward slightly with hard shifts or fast start and stops. We thought it would be a matter of tightening something up and didn't pay a lot of attention to it. Now the driver's seat is also slightly loose. We heard it's not a simple matter of tightening something. The seat motor is good, the seats adjust properly as far as I can tell, just that slight wiggle forward and backward, I guess on the rails.
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Thursday, May 22nd, 2008 AT 1:38 PM

5 Replies

Tiny
DOCHAGERTY
  • MECHANIC
  • 9,601 POSTS
When we got this complaint at the dealer, replacement of the seat rail was the only cure.
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Monday, May 26th, 2008 AT 4:24 PM
Tiny
CARMANIA12
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The problem is fixed in 2 hours max.
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Wednesday, July 23rd, 2008 AT 6:25 AM
Tiny
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I learn something new everyday! Bookmarked them both, thanks for the help!
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Wednesday, July 23rd, 2008 AT 8:11 AM
Tiny
NEOCLICKNCLACK
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I can personally attest to this issue as I just did this repair on my 97 Z3 1.9L and thought I would look for this issue and post my comments for others. This IS a pretty simple fix that anyone can do themselves and once you see how it is done, you can basically pull this off in 15 minutes per side. You could probably make the part easily enough or order the Delrin parts from the other posted link. I bought the Delrin replacement parts from Whalen Shift Machine in the Chicago area and they sell them on ebay now also. Basically they are just hard spacers with holes in them which fill up the gap in the mount. You could probably make the spacers easily enough, but I dont have the time etc for that. These are replacements for the soft rubber gasket material BMW uses which wears quit easily. Delrin is a very hard and tough plastic and I expect these spaces to last for a very long time.
I have a few basic comments for the repair.

You don't need to disconnect any electrical. Just make sure to have space to open the car doors fully and then you should be able to turn the seats over easily enough to work on without disconnecting the electrical.

Once you remove the threaded piece form the seat rails, mark the small slider position relative to the thread with some tape, because you are going to have the fully remove the slider from the thread. You remove the slider from the thread by using a ratchet at the thread end.

Once the small slider is removed, clean all the old rubber out of it. Then put the Delrin spaces in. You will need to sand the Delrin down (they come slightly thick on purpose). I used some fine grit paper and it took a good 5 minutes to sand down by hand. Do this by placing the paper on a flat table and moving the Spacer on it to keep it flat.

And finally dont mix up the rails.

When you put the threads back into the rails, there is are two small plastic pieces on the end of the thread that help lock the item into place within the rail. They are a bit fragile so be careful not to break them.

And then finally, there is a 4 inch square pin which links the thread to the motor which need to stick into the end of the thread. Its a little tricky to get this pack into the thread, but there is a small slot in the rail into which you can get some needle nose pliers or some other item, to get it to fit.

Finally, before you put the seats back, CLEAN the carpet thoroughly. Good luck
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Wednesday, December 30th, 2009 AT 11:26 PM
Tiny
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Look over the information, the hump removal is key to getting more legroom.
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Thursday, December 31st, 2009 AT 8:29 AM

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