Repairing window motors

[b33mer]

I've been sorting out some electrical issues, and throwing some money at the cars lately. So I figured it was time to start a thread, after all who doesn't enjoy watching other people spend money?

Seriously, maybe a few others have travelled these roads before, had the same problems and this thread will be helpful. Electrical issues can be aggravating and can tarnish the enjoyment of an older vehicle. I'm new to e30's but no stranger to classic cars, but that's another story.

Anyhow, I finally figured out what was going on with the inoperable window motors.

Background: The supply of window regulators seems to be drying up, and those available online are typically over $100, even for refurbished.

In my research, I read the 87-91 regulators were different than the earlier design, and the motors themselves would not interchange either. But curiosity got the better of me and I had to see for myself.


Note: 87 on the left

[b33mer]

Clearly the external drive gear is different, but maybe, just maybe the motor would work? Well, the worm gear does in fact have a different pitch so that was kind of a waste of money, but it led to an interesting discovery.


Note: earlier model above

[b33mer]

The stator in the failed motor seemed to turn, but it was being held in place by some unknown mechanism. How complicated could it be?!

After removing the cap with the brushes, it was time to apply a little "persuasion".

[b33mer]

The stator came out along with with the lower bushing.

[b33mer]

The bushing had seized onto the stator shaft. How to remove that bushing? A little more persuasion, this time using a piece of brass rod, to prevent damage to the end of the stator shaft.

[b33mer]

Back to the motor housing, now we can see what is holding the lower bushing in place (it's nasty in there!)

[b33mer]

By prying the stator out of the housing, you can see a starlock washer under the grease and surface rust. The tabs bent upwards when the bushing popped out, but with very little damage. Curious if I could find a replacement, out it came...

[b33mer]

Figuring it was metric, even though it was mangled it looked pretty close to M24 OD. The M12x24.5 in this kit fit perfectly.

[b33mer]

So if you are able to turn the stator on a failed motor, quite likely the bushing is spinning beneath the starlock. The motor does not have enough torque to spin when mounted to the regulator, so it "seizes".

Now all you have to do is clean up the housing, bushing and stator and then re-assemble.

This type of rust remover only goes after rust on steel and iron (read all about chelation). NOTE: Do not use a phosphoric acid based rust remover on the stator!

[b33mer]

Drop the clean bushing into the housing, then use a 5/8" spark plug socket on an extension. With the extension, you can gently tap the new starlock washer into place. Be patient. As an alternative, you can leave the old starlock in place and tap the tabs back down to retain the bushing.

[b33mer]

Grease up the bushing, drop in the stator and replace the motor cap, using a small screwdriver or pick to push back the brushes one at a time.

To test the motor before installing in your car, you can use a 12VDC 0.5A adaptor. This is one that will work (e.g. from an old router). The pigtail is actually a door-side plug but a couple of wires will suffice. Just be careful not to short out your adaptor with a sketchy electrical setup. Polarity doesn't matter - the window goes up and down, right? Motor should spin freely with 0.5A.

[b33mer]

There is a flimsy cardboard-type gasket which is supposed to seal the motor housing. If it tears, then trace out a new one and cut out using an X-acto blade. Motor screws are Torx T25. Be sure to grease the worm gear and re-install the rubber boot/seal for the shaft.

[b33mer]

Seems like a lot of work? Maybe so, but if you're willing to remove the motor from the regulator in the door, then this should be a cheaper alternative compared to complete replacement of the regulator assembly. Good luck!

[efficient]

interesting. thanks for being the guinea pig