PeachParts Mercedes-Benz Forum - View Single Post - how does the window motor know when to shut off?

Nate Stanley · #3 12-13-2002, 09:53 AM

The reason you are hearig the bumping noise is that the regulator and the motor gear have gone out of alignment.

This is because the regulator assembly is mounted on a die casting which warps over time as the window is raised against the stops. This die casting really should have been a steel stamping--

I have had some success in straightening the die casting. but be aware that the casting is brittle and dies not react well to radical changes during the straightening. The 3 mounting legs where it attaches to the door frame must be in the same plane. If you can tweak them into that condition. and at the same time get the motor and window riser gears to be in the same plane as well,
you will be able to reuse what you have.

There is no way to prevent the warpage of the die-cast frame except to use care in raising the windows, and don't let the motor push it too hard once the glass is in its up or down condition.

The rear regulators are simpler than the front ones because the fronts have that idler gear that adds one more element that must stay in proper alignment, and the 3 rear reguators I have straightened in my 2 W123 cars are fine after 2-3 years.