My time for E28 window motors

dbower

dbower

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My summer project is to finally tackle the window motors in my '71 2800CS. Driver door still works slowly but the other 3 are all stuck. I've scanned all the relevant posts here, cleaned the tracks, etc. I want to go ahead and upgrade the motors while I have everything apart.

So, to upgrade my 3 nonworking windows, I'm looking for REAR window motors from an E28. It is my understanding that I need 2 lefts and one right from an E28 to replace my 2 rights and one left (passenger door and rear, plus driver rear).

E28's were made '81-'88, but someone posted to use only '84-'88. Can anyone clarify?

I also need 6 of the rubber bump stops or reasonable facsimiles W&N has them as a last resort.

And finally, of course, can anyone suggest a source for these 3 motors in decent shape? I'll buy 4 if required. Thanks.

Don
 
For the bump stops, see Layne's post:

Window regulator stoppers.

I thought I'd buy all new ones since they are hard and cracked, but I notice there's two different parts. One with a spring 51 33 1 837 518 and one rubber-only, which is NLA 51 37 8 545 198. I don't know how many of each are needed or which positions take which bumper. I found some generic...
e9coupe.com e9coupe.com

I have them in mine, once you have them set for how far up and down you want the window to go, get a razor and trim the side that faces the gear a little so after they compress in time they wont rub against the gear and make a horrific squealing noise. AMHIK. Once that is done they work great.
 
Don:

Some of your questions are addressed in a post I wrote a year-and-a-half ago at: https://www.e9coupe.com/forum/threads/a-few-tips-on-installing-e28-window-motors.27320/

E28's were made '81-'88, but someone posted to use only '84-'88.
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Yes, I believe that's true. The website I learned from - located at: https://sites.google.com/site/kdelimon/windowmotorconversion1 - also specifies '84 - '88. Be sure to get motors with 8 tooth output gears. Later BMW and some Porsches used identical-looking window motor-gearbox units, but with 10 tooth gears, which won't mesh with the big gear on the e9 regulator.

can anyone suggest a source for these 3 motors
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Contact e9coupe contributor "Koopman" He often has them - I got mine from him.

If I were you, I would do the driver's door too while you're at it. That's the window you use the most and you'll really appreciate having fast windows when you need to grab a parking lot ticket or visit a drive-through ATM.
 
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Bosch part numbers should end in 026 and 027. Sorry, don't have the full part #s. And not sure which is R and which is L.
 
Opposite of BMW which parts ending in odd numbers are always driver's side and even are passenger side. Bosch numbers ending 027 is for the passenger side and 026 is for the drivers. I will have a set in the next two weeks.
 
Shipping discount now at W&N
 

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jmackro said:
Don:

Some of your questions are addressed in a post I wrote a year-and-a-half ago at: https://www.e9coupe.com/forum/threads/a-few-tips-on-installing-e28-window-motors.27320/



Yes, I believe that's true. The website I learned from - located at: https://sites.google.com/site/kdelimon/windowmotorconversion1 - also specifies '84 - '88. Be sure to get motors with 8 tooth output gears. Later BMW and some Porsches used identical-looking window motor-gearbox units, but with 10 tooth gears, which won't mesh with the big gear on the e9 regulator.



Contact e9coupe contributor "Koopman" He often has them - I got mine from him.

If I were you, I would do the driver's door too while you're at it. That's the window you use the most and you'll really appreciate having fast windows when you need to grab a parking lot ticket or visit a drive-through ATM.
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Thanks, jmackro. I have had good experience with Koopman on previous purchases. In this case, I found the motors that I need at a recycling center (junkyard) in Florida and they are on their way to me now -- along with the bumpstops that Steve recommended from McMaster. Thanks all.
 
Question for the group on motors. I bought a pair of E28 rear motors for my 74 E9 and have almost finished installing the passenger side. I tested the passenger side motor on the leads in the car and it worked when I activated the rocker switch, so I re-assembled the motor and regulator and reinstalled it. Went for the moment of truth and the motor ran for about 5 seconds and stopped; rocked the switch back and forth and nothing. Checked fuses and nothing was blown. Took the motor off the regulator, disconnected the leads and put my meter on the leads connected to the switch; there's power. Put the driver's side motor on and it worked. Put the passenger motor back on and it didn't, at all. Took the passenger motor inside to my bench and hooked it up to a small 12 volt battery; ran like a charm.

Took it back out and reconnected it. Nothing.

Electrical work is not my forte, so any ideas on what is going and how to fix it would be most appreciated.
 
If I understand you correctly you have one motor that works fine when installed on the passenger side, and one motor that does not work on that same side yet spins with no mechanical load.

Failing to work under load could be an electrical problem or a mechanical problem (at the output gear). When motor windings overheat you can generally smell it. Any motor overheat smell during or after the 5 seconds it worked? Overheating can burn the insulation of the copper winding so one would expect lower resistance and of course lower magnetic field from such a motor.
 
Replied to this from email instead of using the forum; apologies if this shows up twice:

I just went out and reconnected the E28 passenger side motor to the power leads and it worked (what the?!); so then I connected it back to the regulator to test it and it worked fine in both directions (not with the window attached, just the regulator). As I was finishing taking it back and forth through repeated open and close cycles, it stopped.

So I took the window motor off the regulator and put it back on the power leads in the car. Nothing. Then I took it back to my bench and connected it to my 12 volt battery. Nothing.

Got the ORIGINAL window motor and tested it with the stand alone battery, it worked fine. I tested the resistance of the ORIGINAL window motor and got 1.7 on my multimeter.

When I tested the passenger side E28 window motor, I get a resistance of .5. However, when I test the E28 driver's side motor, I also get .5 and that motor seems to work fine.

I have never smelled any burning when running the E28 passenger side motor; when it runs it seems to run fine. Then it just stops and this time it appears to not be restarting.

Any thoughts? If it's shot then I need to contact the seller and figure out next steps.
 
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