'86 420: Rear window not working - plastic "sliding jaw" was broken. Ordered a new one but can't figure out how to install it. The metal button on the regulator arm does not seem to fit into the sliding jaw. There is a brass-colored metal piece in the new part, I didn't notice in the broken sliding jaw. Even if I removed the metal piece, the metal button the regulator arm would not fit into the hole in the plastic sliding jaw - too small in diameter. Could it be that the old metal piece is in the regulator arm? If so, it doesn't look like the brass colored piece in the new part. Following is a picture of the piece I ordered:
http://catalog.eautopartscatalog.com/tayco/image.jsp?title=Window%20Regulator%20Kit&url=http%3A//img.eautopartscatalog.com/live/O304116660FEB.JPG

You have bought exactly the right part.

1) There is a portion of the old plastic piece still in the regulator. It is the steel piece in the center of the plastic. You must remove this piece. To remove it, get a Dremel tool and grind the raised portion of the steel pin on the back side of the regulator. It is peened over and you must grind off all the peened metal to get it out.

2) Now that you have a hole in the regulator, you can insert the pin from the new plastic piece. BUT DON'T DO IT NOW. Carefully take the plastic piece apart. It is a three piece deal. Two plastic halves that trap a steel center.
Once the plastic piece is apart, set one half of the plastic piece, together with the steel pin, into the regulator.

3) Carefully set the regulator down so that the steel pin is pointing upwards through the regulator and the face (bottom) of the pin is supported on a very rigid surface (steel table). BE SURE that the steel is supported and NOT the plastic.

4) Now, carefully peen the steel pin over with a ball-peen hammer to mushroom its face down onto the regulator. It's quite soft so this is not difficult, PROVIDED that you have properly supported the bottom face.

5) Reassemble the plastic pieces together (don't lose the rubber bumpers inside) around the steel central portion.

6) Put the regulator back in the vehicle.

Good luck.

I just did this repair without removing the window motor from the door.

One important note is the inner door panel isn't held by clips, there are 4 or 5 plastic legs that slide down into slots. If you try to use a pry-tool the legs will break off. Remove the tiny screw from the bottom-center of the inner door panel, and push the panel upwards, the legs will come out of the slots without breaking. Of course, first you remove the lock-knob, the plastic cup at the inner door handle, the main door handle, the chrome door latch trim, and the window switch.

Then I drilled a tiny pilot hole in the center of the old peened stud on the arm, 1/2 way deep into it. Then I drilled it out with a larger bit just enough to cut loose the peened shoulder. Carefully knock out the old stud.

I peened over the stud in the new plastic slider by supporting the back side of the small part with a socket for a 1/4" nut. The O/D of the socket exactly fit inside the plastic hole in the back of the plastic slider. Then I backed the socket by hand, with a 2 pound auto body dolly. The 2 pound mass of metal absorbed the inertia of the hits by the ball-peen hammer, so the arm doesn't get bent.

You don't need to hit the stud very hard with the ball-peen hammer, the metal is pretty soft. Remember to put the small spring washer back on the stud before peening over the stud; I forgot, its too late now.

I made an alignment mark on the part that stops the downward movement of the window arm, and removed that part from the arm. Then the window slides down a bit further than usual so the slider can be put into the end of the track. Then put the stopper back on the arm.

I used a few dabs of contact cement to re-afix the plastic vapor barrier, and the door panel went back on just fine.

those original style ones are junk. they will break quickley.
you need to get the solid ones sold by i.m.c.. they will last forever.
otherwise the repair advise is spot on.

george

I too just went thru this - 126 model - drivers side rear door.

Following the advise of another member here, I used a clevis pin instead of battling with the rivet that must be peened.

Dremeled off the old rivet with arm extended downward. Drilled a 5/16" hole thru the spot where the rivet had originally existed. Bought a 5/16 clevis/2" long from Home Depot. Cut it down so there were 2 holes left on the clevis. If you don't do this, the pin will collide with the window. Ran it thru plastic bushing(sliding jaw), then thru hole in arm and secured with cotter pin. Good as new and no need to remove the regulator, motor, arm, etc. and battle with peening a rivet that will likely cause you to break the $10 plastic bushing.

My 2 cents.

__________________
Mike Murrell
1991 300-SEL - Model 126
M103 - SOHC
"Fräulein"