E28 window motor observation.

Mike Goble

Mike Goble

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I acquired a couple of E28 rear window motors a while back and one of them wouldn't hit a lick. It's not an item you would return since you won't find an exchange in the 30 days they give you as it's a pretty rare part. So, I got the electric motors from the front windows, leaving the gearbox on the regulator. As it turns out, they are identical, and now I have another set of working window gearboxes.
Front motor on the right, rear motor on the left.
 

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That is huge, you just doubled the supply of motors, therefore prices should drop in half :).
I always prefer rear gearboxes in any case because rear windows get very little use.
 
Arde said:
That is huge, you just doubled the supply of motors, therefore prices should drop in half :).
I always prefer rear gearboxes in any case because rear windows get very little use.
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About half right there. Only the rear gearboxes work in the conversion, but the electric motors can be from the front as well, so the same number of gearboxes but more motors that will replace a motor that fails.
Note in my picture that there isn't a gearbox attached to the motor.
 
Sounds like it's simple. So what your saying is the motors are the same but the gearboxes are different on the front E28 motors.
Thanks
 
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Arde said:
Ok, hoard gearboxes then.
Electrical motors seldom fail...
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I've had two motors that didn't work after I got them home. The gearbox only fits one side, so you need two of them. They have a much lower failure rate than the motors. Having a spare motor would pretty much cover the bases.
 
I can't see this being an advantage to getting E28 motors. Where can we find gearboxes without motors? The only advantage is if a motor goes bad you could buy a front assemble and use the motor since they are the same so there is no way it can double the set up for the rear window motors. Just my opinion.
 
jmackro said:
And how different are the front gearboxes? Do they still have the 10-tooth pinions? Is it just the mounting bolt pattern that differs? In other words, when the world's supply of e28 rear gearboxes runs out, can the fronts be adapted?
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Koopman said:
I can't see this being an advantage to getting E28 motors. Where can we find gearboxes without motors? The only advantage is if a motor goes bad you could buy a front assemble and use the motor since they are the same so there is no way it can double the set up for the rear window motors. Just my opinion.
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The front gearboxes are very different. There might be other versions of gearboxes that may be more adaptable, but I haven't found one yet. I do poke around in the local junkyards quite a bit, so if I find something that looks promising, I'll write it up.

This isn't going to make any more E28 motors, but it will lessen the pain of finding a pair in the boneyard, spending the time to remove them then getting them home only to find that one or both don't work. This happened to me and this is why I wrote this up. You want the unicorn you just found to work.
 
Mike Goble said:
The front gearboxes are very different. There might be other versions of gearboxes that may be more adaptable, but I haven't found one yet. I do poke around in the local junkyards quite a bit, so if I find something that looks promising, I'll write it up.
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OK, thanks! I have replaced my front pancake motors with e28 motor/gearboxs and can report that they work great.
 
Absolutely not. I think the E24 has a 12 tooth gear. I believe the E12 uses the same motor and gearbox.
 
jmackro said:
And how different are the front gearboxes? Do they still have the 10-tooth pinions? Is it just the mounting bolt pattern that differs? In other words, when the world's supply of e28 rear gearboxes runs out, can the fronts be adapted?
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Yes, it is not that big of a deal. I acquired all four window mechanisms from a 528 and installed them in my 2800CS. I did have to cut the door inner panel a bit to provide clearances, but they work great.

In my case, I guess ignorance was bliss. I didn’t know they didn’t fit.
 
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