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1994 S600 Coupe, 1995 S600 Coupe
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2,016 Posts
Discussion Starter #1
Coupe rear window regulators fail for a variety of reasons. Lack of, or very old and gooey lubrication doesn't help matters. Coupled with the window drop feature whenever you open the doors, and the heavy windows, the regulators take a beating. Fortunately, the plastic piece that breaks is common with other European cars. New cables are made from model airplane parts. The job is not hard, but takes awhile, especially removing and replacing the regulator. This is a whole lot cheaper than a new regulator, even if someone does the work for you.

This procedure will likely also work on sedan cable assemblies, but I have no experience with them.

I won't go into everything required to get the regulator out of the car, but here's a summary:
Remove lower seat cushion
Remove side inner side panel
Remove rear outer lower body cladding
Remove seat belt presenter mechanism
Remove black plastic cover over the regulator, then disconnect the connectors from the regulator motor
Remove the black metal cover that sits under the seat belt presenter mechanism.
One way or another, raise the window to remove the bolts holding it to the regulator, and remove the window from the car. This is tricky, but it comes out toward the outside of the car.
Remove the round covers that are found under the body cladding, and loosen, but don't remove the nuts found underneath on the adjusting screws for the regulator
Remove the regulator motor
Remove the upper bolts holding the regulator to the body.
Remove the regulator from the car. You may have to raise or lower the window regulator mechanism on its tracks.

Once the regulator is out and on the bench, you will likely find either a broken cable, or a broken cable attach block on the mechanism, or both. The first picture shows mangled cables, and a broken block from one of my mechanisms. The block had cracks elsewhere, so I'd recommend changing them whenever the mechanism is out of the car, broken or not. The side of the blocks break out, allowing the cables to come out and get tangled up. A broken cable has the same effect. The bottom line is if your window doesn't work, STOP. Don't continue to try to raise or lower the window, as once the cables get into this mangled condition, they are useless. If they are still more or less straight, they can be reused.

Order the following parts:
Cable block:
https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.com/ulk/itm/123684514062

Du-bro 48" flex cable assembly:
https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.com/ulk/itm/302002941804, or local hobby shop

Great Planes 1/16" brass wheel collars:
https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.com/ulk/itm/401764419771, or your local hobby shop

Very small washers that are same size as the spring OD on the cable

Plastic compatible lubricant

It's also common for the clips that hold the pulleys and other parts on the mechanism to break. If the do, order N912007006001 clip from your Mercedes dealer.

You will also need a heavy duty soldering iron, solder and flux.

I have not found replacements for the white pulleys, but none have broken on my two cars, so I haven't looked too hard.

I tried bicycle cables, but they are too stiff for this purpose. The Du-bro cables I recommend are very flexible, and the right diameter to work well. They also have the advantage of being solderable.

Disassemble the entire mechanism. The winder pulley is held on by two torx screws on the back of the regulator. Clean all three slide tracks front and rear with alcohol to remove all grease and dirt. Clean the pulleys and bearing surfaces. Also clean the yellow winder pulley. You will grease things as they are reassembled. Be sure to grease the tracks front and rear.

Keep your old cables as you'll need them to get the proper lengths. The original cables had ends crimped on, but we will be using the wheel collars and solder, as crimping tools are very expensive.

Basically, slide the spring on the cable off the opposite end of the cable. It will be reused. Make the longer of the two cables the same length over all as the old one. Slide on the wheel collars on on end and tighten it down with the set screw. Solder that collar on. File opposite sides of the collar flat, so it will fit into the yellow winder pulley. Slide the spring on the opposite end of the cable, then the washer, and finally the other wheel collar.

Start making the second cable, BUT DO NOT CUT IT TO LENGTH!! Rather cut it a little long. Run the slide mechanism to one end or the other. Wind cable attached to that end around the yellow plastic drive pulley that is driven by the regulator motor. Wind the other cable around the pulley, then slip the other end with the spring and washer into the cable block. Adjust the wheel collar until both springs are about half compressed. Make sure the cable is around both pulleys. Solder the wheel collar on, and cut the excess cable off. Snap the cover on, install the flat washer and clip. BTW, I had the grind down the circumference of the washer slightly to fit the new block.

Have fun!

Jon
 

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Registered
1994 S600 Coupe, 1995 S600 Coupe
Joined
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2,016 Posts
Discussion Starter #2
I now recommend using silver solder to solder the collars to the cables. I also use two collars at the new blue plastic center piece because it is trying to pull the cable straight thru the collars. I also use a vice and slightly crush the collars on the cable. The cable ends that wrap around the winder pulley don't seem the be an issue.

Cable length is critical, so that the springs in the center keep constant tension on the cable. They should be compressed almost to binding when installed. The heavy window glass stretches the cables a bit. Any slack causes issues.

Jon
 
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