While investigating my Rear Drivers Side Window not going down I removed the Door Panel and found that my Window Regulator was bent and had most of the gear teeth on the Regulator severely worn and rounded off.

The Door Panel came off easy enough that I took a look at the Rear Passenger Side Window Regulator also. I found that while the Regulator Gear Teeth were in much better shape the Window Regulator Mounting Plate was bent and warped worse than the opposite side.

I ordered a new Regulator for the Drivers side. When it arrived I found that it was an original Mercedes part and that they had not taken any opportunity to strengthen the Regulator Mounting Plate (adding a reinforcement plate). To me this meant that the Mounting Plate was going to get twisted up again.

I decided to make a Steel plate to overlay over the original so that in the future it would not bend.

I made a cardboard template and rooted around in my Garage until I found some suitable scrap metal

The cutting of the metal involved a Sawsall, metal cutting Hole Saws and a Die Grinder with a Rotary File on it to approximate the shape of the Plate; and Drill Bits and Motor do drill the bolt hole for the Motor.
I also removed the curled Spring that attaches to the Regulator Arm Pivot. I felt the Spring was just 1 more item to put stress on the Regulator Mounting Plate.

I installed the assembly and it is working fine; even without that curly Spring that I removed.

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84 300D, 82 Volvo 244Gl Diesel

The Passenger side rear was a different story as besides making another reinforcement plate I would have to straighten out the old twisted Window Mounting Plate (I did not want to buy a new one for this side as the gear teeth were still functional and that Window does not get used much).
I used the same cardboard template but reversed; and made another reinforcement plate and added a little extra metal to part of it. I added the extra as my intent was to use clamps to straighten everything with Epoxy Glue between the reinforcement plate and the Regulator Plate and I needed that extra metal to keep the Regulator Plate straight. (Cutting the 2nd reinforcement plate went faster.)

I also removed the curly Spring from the used Regulator Plate but went a step further and cut of the raised area on the plate that one end of the Spring attached to so that area would be flat; the extra metal I added would go over the top of that area.

After the reinforcement plate was cut I clamped it to the Regulator Plate with no Glue. I did not put Glue as I was worried that the Regulator Plate might crack when bent back into shape. I let it sit clamped overnight in hopes that the Regulator Plate would want to stay bent back in shape.
The next day I cleaned and degreased both plats and Epoxied them together and clamped them a gain.

After the Epoxy cured I installed the Regulator and it works OK.
The results of the straightening were not perfect but worked enough to be functional.

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84 300D, 82 Volvo 244Gl Diesel

More pics.

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84 300D, 82 Volvo 244Gl Diesel

That's pretty slick. Do you think the teeth in the gears will work properly?

I have always hated "Pot Metal"

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'84 300SD sold
124.128

I have been using it and it is working fine. Sometime a small amout of noise going down.

The one I reused/fixed; the rear passanger side had better teeth the the other ther side. They are worn an an angle but still have their points.
That combined with the fact that, that window is not used as much as the other 3 means that it should still have some life in it.

The metal on the Regulator Gear is soft. I could see no wear on the Motor Gears.

I actually was considering welding the edge of the gear and filing new teeth on it. The worn teeth are in the central 50% of the teeth. The teeth on the ends were complete and not worn and a pattern/template could be made from them as well as the radius.
It would not be too hard to do; just time consuming; it would have meant rough cutting the teeth with a Die Grinder with a Cuttoff Wheel on it and finishing the job (while I watch TV) with a triangular file.

If I find a good one at the a junk yard to replace it I can heat the Steel Plate to I put on the Old one to burn the Epoxy; take it off and transfer it to the Junk yard one; so that one will not bend.

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84 300D, 82 Volvo 244Gl Diesel

Yes.
This is one time when a nice thick Sheetmetal Stamping with some stiffening ribs would have done a better job.

I thought the new one I put on the Drivers Side Rear might be made thicker but it was not so.
I was suprised that I was sent an Origional Mercedes Regulator (had the Mercedes Star and part number on the tag as well as a Star on the Regulator Arm).
It may be some aftermarket company makes thicker ones.

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84 300D, 82 Volvo 244Gl Diesel

I thought I would get criticized for removing the springs!
The springs seemed like useless parts that only put more tension on the Regulator Plate.

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84 300D, 82 Volvo 244Gl Diesel

Ten years ago, I repaired the power-windows on a friend's 80 rustbucket 300D. All of the alloy regulator frames had badly twisted and the driver's frame was actually broken. Got replacemnt regulators for the fronts from Potomac German Auto in Maryland, and they were obviously a redesign, with a thicker casting and extra stiffening ribs. Unfortunately, no 'improved' regulators were availible for the rears, so I straightened the originals as much as I dared, and fabricated a pair of steel reinforcing plates. I didn't remove the regulator counterbalance springs, and that car has probably long since been junked anyway.

Happy Motoring, Mark

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DrDKW

Diesel911,

Does the bent piece and worn gears result in a clicking noise as the window goes up and down?

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AJ

1985 300D (SOLD)

It can. If yours are origial, it would bea good idea to check them, and at least lube the gears, pivots and channels where the lifting arms attach at the bottom of the glass. A bit of silicone spray might reduce friction in the window tracks.

Happy Motoring, Mark

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DrDKW

In my case it was the worn at an angle teeth that were making the clicking noise.

Before I replaced the Right Rear and straightened out the Left Rear Window Regulators they both made clicking noises.

After the repair and replacement of course the Right Rear makes no noise and the Left Rear will click a little after it is 2/3 rds of the way down. Going up it makes no clicking noise.
The clicking is not a problem for me as I almost never roll the Left Rear Window down more than 1/2 anyway. I am just sooo... glad to have all of the windows working.

I would like to have done my repair job on the Right Rear Regulator but the Gear Teeth were just too badly worn to salvage it.
I think I could have welded new metal on the teeth and filed them down and made the old Regulator work but it was just too much work and my welding skils are patetically out of paractice.

Several days ago I welded a broken off piece of my Computer Desk Chair and had a lot of trouble with a simple job.

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84 300D, 82 Volvo 244Gl Diesel

Ounce the Regulator Mounting plate is warped the Gear Teeth on the Regulator Arm (the steel teeth are soft metal) will start to wear on an angle. On my Right Rear the end teeth were rounded of and would no longer move the window up.

The Gear on the Lift Motor showed no wear at all; indicating that they must be hardend steel.

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84 300D, 82 Volvo 244Gl Diesel

Good write up! I bet someone could make money selling regulators with the steel reinforcing plates.

Unfortunately I think there is a limited market.

I think if the Regulator Mounting plate was made of Steel to begin with and some ridges were stamped into it in the areas were it is inclined to bend the problem would be solved.

I thought that the New One I ordered would be an aftermarket one and that it might have a thicker casting.
But, the one they sent was OE; from Mercedes itself; and Mercedes did not see fit to thicken their casting of the plate.

If a big Punch Press was set up you could easily punch out enough Steel Plates in an 8 hour day to supply the needs whole US. Even with the need to weld on the bushing areas that the arm pivots from.
Not even a big enough market for them to be made in China.

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84 300D, 82 Volvo 244Gl Diesel