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BMW 3-series 92 Thru 98 Electric Seat Repair – E36

May 21, 2010

Are you having troubles with the power seats in your 3 series 92 thru 98? Are the seat back recline and or the seat bottom up-down actions not functioning? You’re not alone. While these problems could be due to a number of things (including faulty motors), the most common cause is failure of some small plastic gears inside the motor gearbox assemblies. One gear is for the recline function of the seat back; the other gear is for the up-down function at the rear of the seat bottom. Previously, the only fix was to replace the complete gearbox/seat frame assembly (for about $400-600!). But now we are offering inexpensive replacement gears (part #SG 1000) so you can once more have a fully functional seat. Following are the basic steps for replacing the faulty seat gears:

1) Raise the seat to the full upright position. Remove the four hex-head bolts securing the seat to the floor (move the seat forward and back, to access the four bolts). Disconnect the battery’s negative cable to prevent any SRS codes from being generated. Tilt the seat assembly up and back and unplug the electrical connector plugs. Remove the seat from the car.

2) Set the seat on the floor, upside-down. Remove the plastic cover from the rear motor/gearbox assembly. Position the seat on its side, with the gearbox toward the floor and the motors upward (figure 1).

3) Remove the four Torx-head screws securing the motors to the gearbox. Remove the motors from the gearbox, noting the position of each motor. Note that three screws are readily accessible; the fourth can be accessed after the rearward motor has been removed (figure 1).

4) Remove the six Torx-head screws securing the cover to the gearbox, noting the positions of the different length screws (figure 2).

5) Remove the gearbox cover by gently tapping it with a mallet and prying with a screwdriver or similar tool (figure 3).

6) The gear closest to the seat bottom is for the up/down function at the rear of the seat bottom. The other gear (closest to the vehicle floor, when installed) is for the seat back recline function (figure 4). Relieve the pressure on the gears by gently moving the seat back as required. Remove the broken plastic gear and shaft assembly. Clean out all broken pieces and grease from the gearbox.

7) Remove the circlip securing the plastic gear to the shaft. Remove the gear and install the new gear (figure 5). Replace the circlip. Re-grease the gearbox and install the gear and shaft assembly into the gearbox. Reassemble the gearbox cover, motors and plastic cover. Install the seat into the vehicle and reconnect the battery cable. Now climb in, adjust the seat to your preferred position and drive in total comfort once more.

Bavarian Autosport

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Categories → 3 Series 92-98 - E36

  1. MOHAMED KHAN permalink


  2. Tom permalink

    That back torx bolt on the front motor is a real pain. Make sure you have either a socket and a universal joint or some really loose extensions. Even with them, it was a battle.

    Also, somehow I got the large front gear out of whack (while doing the reclining rear gear). Anyway, the lower teeth will unseat from the large height gear (deep in the mechanism). Just ease the brass gear off, and then the entire unit below will come out as one piece (be patient here). Then with some testing you can get it aligned and seated properly.

    Thanks for the write-up and the gear. So nice to have a fully functional passenger seat again in my 161K mile M3.


  3. Pete permalink

    Great write-up you guys, can’t thank you enough. I had no problem with the back torx bolt. I think it may be because I released the back rest and folded it forward befor taking the seat out of the car and left it that way out of the car. It raises the seat a little bit away from the seat mount rails, giving you more room to work. Don’t forget you need your radio code when you reconnect your battery.

    Thanks again, Pete.

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