The fork lock is mounted to the steering head and the seat lock is mounted in the rear sub-frame. I remove them so I can powder coat the frame and the sub-frame.
Remove Fork Lock
The fork lock mechanism is retained by the lock cover. The pin holding the cover keeps the key assembly in the frame.
Fork Lock with Cover
I use a large blade screw driver and put it through the gap between the steering head and the down tubes with the blade against the back side of the cover as near to the cover pin as I can.
Remove Fork Lock Cover
I use a plastic mallet and hit the screw driver a couple stout wacks to start driving the pin out. As the pin slides out, it becomes easier to bend the cover plate. So once the pin is loose and there is a gap between the cover plate and lock housing, I use a smaller blade screw driver to pry the cover plate pin out of the frame.
Remove Fork Lock Cover
Fork Lock Cover Hardware Detail
Fork Lock With Cover Removed
Next, I insert the fork lock key into the lock, turn it while at the same time pushing up on the key a bit to keep it in the lock and pull the key backward. The lock mechanism comes out of the frame attached to the key.
Removing Lock Mechanism-Insert Key
Removing Lock Mechanism-Turn Key Counter-clockwise
Removing Lock Mechanism-Pull Lock Out
Fork Lock Removed
Fork Lock Hardware Detail
Remove Seat Lock Assembly
The seat lock assembly is secured to the rear sub-frame with two long screws from the inside of the sub-frame. There is key lock on the outside of the rear sub-frame next to the grab handle.
Rear Sub-frame Has Seat Lock Next To Grab Handle
There is a metal housing holding the seat latch components on the inside of the rear sub-frame.
Seat Latch Mechanism is Inside a Housing on The Inside of the Rear Sub-frame
I remove the two Phillips head screws from the housing.
Remove Seat Latch Mechanism Backing Plate
Seat Latch Mechanism Backing Plate Hardware Detail
Seat Latch Mechanism Backing Plate Detail
Part of seat lock mechanism is inside a shell. The mechanism includes a lever that catches the seat pin locking it down, a lever return spring, and the lever pivot pin that goes through the center of the return spring.
Seat Latch Mechanism Parts Detail
Seat Latch Mechanism Parts Detail
I remove the lever, pivot pin and spring. The pivot pin is secured with a cir-clip on each end of the pivot pin. I remove them using cir-clip pliers.
Seat Latch Lever Pivot Pin C-Clip
Remove Seat Latch Lever Pivot Pin Cir-Clip
Seat Latch Lever Pivot Pin C-Clip Detail
After I remove one of the cir-clips, I push the pin out the other side of the shell to remove the spring and the lever.
Removing Seat Latch Lever Pivot Pin
Seat Latch Lever Pivot Pin & Spring Assembly Detail
Seat Latch Pivot Pin Hardware Detail
Seat Latch Arm Orientation
Seat Latch Mechanism Parts Detail
I push the button out of the shell.
Seat Latch Push Button Pulls Out
The lock fits in a ring that is secured to sub-frame with a small Phillips screw . It has an arm that prevents the lever in the shell from rotating which locks the seat.
Seat Lock Orientation
Remove Seat Lock
Seat Lock Lock Ring Detail
The lock retaining ring has a triangular section that fits into the triangular space on the lock.
Seat Lock Mounting Detail
Thank you for the article. I have the exact lock combo above but no key. I have a blank and the key code but apparently BMW no longer makes locks for 1971’s. I can make the key myself but need guidance on how to get the tumbler out of the seat lock assembly (your last photo). That ring with the tab have to come off the end of the tumbler assembly. How do you get that off. there looks to be a pin pressed into the side of it and it is not clear if that needs to be drilled out, or perhaps it can turn. Any help is appreciated.
Hi G,
I’ve never tried to remove the tumblers, so I don’t have any information to assist you with that.
Best.
Brook.
My BMW R100s seat is locked closed, the release button nor the key turn. How do ai open the seat lock if Stuck ( without breaking with a hammer
Alex,
It’s possible the seat lock is rusted so it won’t turn. You could spray some Kroil, or other penetrating oil, into the key slot of the lock and let it set for awhile to see if it helps the key turn.
If you lie on your back and look up at the front hinge on the right side of the frame, you should be able to see the three Philips head screws that secure it to the seat pan. If you use a long shaft Philips screwdriver you should be able to remove them and pull that hinge off the pin. That may let you move the seat enough to get free of the latch.
There is also a clip on the rear hinge pin that can be removed so you can pull the seat to the rear off the hinge pins and then lift it up.
I hope this helps.
Best.
Brook.