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Subject: How to disassemble the front seats Author: DavidC (moderator) : member since December, 2003 : 11918 posts Posted on: 2004-04-16 20:50:00

When I purchased my '86 735i last summer, I anticipated that there would be some fixing up to do. After all, the car is nearly 20 years old. Having just completed a fairly substantial transformation of a '97 e38 (740iL), my wife and I were enthusiastic about the possibility of ending up with a nice car for a relatively small investment compared to the cost of a new car. We love old bimmers, too, so what else would one possibly even consider throwing so much effort and money into?

Anyway, the '86 e23 turned out to be a LOT more work than we ever imagined. I purchased it sight unseen, other than the photos on the ebay auction, for $1600 from a fellow in Michigan. It had a blue leather interior, which is my favorite color for this model, and a limited-slip differential plus new TRX tires (worth $800 by themselves).

We got a cheap Airtran flight from Atlanta to Flint and the seller picked us up at the airport. When I saw the car in person, it wasn't quite as good as the description the seller made it out to be. The photos were, in my opinion, suspiciously missing several major flaws, such as two large dents in the roof above the rear window (caused by the delivery truck, according to the seller, but he didn't bother to have it fixed) and a bit of rust on the rear wheel wells.

The car started reasonably well and it drove acceptably, too. The blue leather interior, though faded, was in excellent condition. The air conditioning didn't work at all. It just blew hot air. I knew that might be a problem point, but I liked the car and could see good potential, so I paid the seller and we drove the car 800 miles back to Atlanta.

Since then, we've done a lot of work to the car, much of which is chronicled here on BimmerBoard. As part of the leather seat restoration, we had to completely remove and disassemble the front seats (and the rear seats, too, but that's for another post).

The nitty gritty...

First, remove the front seats. Start by noting the location of all the connectors and wires under the front. It helps to label them. Pull out the headrests. This will make it easier to get the seats out of the car. Elevate the seats to the highest position, then use a socket wrench (17mm, if memory serves correctly) to remove the four bolts securing the seat to the floorboard. You'll need to move the seat back a bit to access the front bolts, then forward again to access the rear bolts. After that, you can unplug the wiring harnesses under the seats.

It helps to have a workbench to place the seats on so that you can work without bending over. Believe me, investing in a pair of sawhorses and a sheet of plywood is worth it. From this point on, I'll talk about "seat" instead of "seats". The same procedure applies to both seats.


We're going to separate the metal underframe of the seat from the seat cushion. Turn the entire seat over and look for the black wires that lead from the frame to the seat cushion and seat back above it. You'll need to cut three of them. I suggest using colored tape to mark the wires so that you'll be able to quickly reconnect them when we're done.

The next three photos show how you unscrew the four bolts that hold the seat frame to the seat bottom.





Remove the seat back. There are two screws along the bottom, two screws above the magazine pocket and two metal guides at the top.


Remove the two screws behind the armrest.


And pull the armrest away.



Pull the black wiring harness through the pivot hole in the sides of the seat. This seat has heat, so you may not have as many wires if not similarly equipped.


Now we're going to remove the worm drive.


Remove the four screws on the black cover plate. Be careful not to let the parts fall apart. Everything is really greasy, too, under the plate so have some paper towells on standby. You'll get dirty.


A view of the internals of the worm drive. The piece on the right is the underside of the white, rectangular plastic piece in the previous photo.


Lift the worm drive away from the frame. I recommend putting the black metal plate back on, with the four screws, to keep the worm drive mechanism in one piece while you work on the other parts of the seat.


Here is a closeup of the gear that the worm drive turns to adjust the seat back. There is another gear on the opposite side of the seat (sans motor). When you reassemble the seat, the two gears have to be in the same position to avoid seat twist. You can use a flat-blade screwdriver to move the gear.


Remove the C clip.


Remove the bolt, in the lower right corner, to detach the gear assembly from the seat.

Fix any problems you see with the wiring or the alignment of the gears, then reverse the steps to reassemble. If your power headrest isn't working, see my previous post, Power headrest cable repair. The same technique described in that article can be applied to correct problems with the flexshafts controlling the seat back adjustment, too.

David Cecil
'97 740iL, 119k miles
'86 735i, 91k miles
'77 320i, 140k miles

www.e38.org has links for everything about your BMW 7-series automobile

• How to disassemble the front seats (pic) (url) - DavidC 2004-04-16 20:50:00 (9789 views)
  • Re: How to reassemble the power control box for the front seat - toups 2004-04-28 05:20:34 (1032 views)
    • Do you mean this? (pic) - DavidC 2004-04-28 10:11:46 (1182 views)
      • Re: Do you mean this? - toups 2004-04-29 16:51:20 (773 views)
  • Wow! Fantastic write up! Thanks! (nt) - erwin8r - '86 L7 2004-04-19 11:11:44 (627 views)
  • You're awesome at the step-by-step, keep up the good work ! (nt) - Kevin '86 735i VA 2004-04-19 00:48:42 (614 views)
  • Great post David. This one is a keeper. (nt) - Jeff '84 733i 5-Speed 2004-04-17 15:22:04 (540 views)