E9 front window regulator.

My mechanic Matt successfully mounted the Porsche regulators to the front windows. The problem was the holes on the new regulators were more recessed than the originals, hence he used shorter mounting bolts. Works like a charm.
 
I am. My mistake. They are the motors from a ‘91 Porsche 911 I believe. They are nearly identical, but the seat for the bolts are more recessed than the original ‘74 motors requiring shorter mounting bolts. Thanks for the clarification.
 
Comparing to picture in post #11, what is distance between gear and mounting thread surface? (if you still have the first replacement motor)
Did you happen to check gearbox gear to regulator gear engagement - fairly centered or not fully engaged?
On your picture the motor on left does not appear to have a centering shoulder on one; did you have to modify in any way or did it make no difference?
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This is what trying to compare on the 911 motors - if you still have your first replacement (broken window one) would you be willing to sell or lend it to do head to head comparison? As long as the mounting point surface to gear distance is within range whether motor sits closer or further to regulator gear should not really matter (unless it hits something else).
Alternatively new counterbored spacer sleeves would not be too hard to make if that's what it takes to line up the two gears.
 
The motors are from a 1975 Porsche. No need to have the centering for the bolts, however because the Porsche seats are more recessed, shorter bolts are required. I do have the older motors if needed.
 
Think the recess shoulder handles a lot of the torque, allowing the bolt to just have to hold gearbox in place. Without it the bolt is in shear (in a somewhat larger hole), tends to get loose, wallow out hole.
Having two out of three shoulders is probably ok as in the one on left side of your picture. Shorter bolt would prevent bolt rubbing or locking up the gear inside with a thinner gearbox case (more recessed as you put it).
What I'm interested in learning is if the motor driving gear to regulator driven gear alignment with the Porsche motor is the same as with the BMW motor or if it is offset, possibly leading to eventual problems. Guess I'll just order a Porsche motor and see.
 
My mechanic said that the gear of the Porsche motor did not reach fully with the regulator. By the picture, it is a little shorter than the oem. He also said that enough of the gear did engage and was very sure it would not be a problem. If I thought he was ever slightly iffy, I would have gone in a different direction. Time will tell.
 
BTW, if anyone is in the Greenville SC area, I highly recommend Matt who works at Thunder Bunny Racing. His email is [email protected]. Very meticulous, knowledgeable, and a bimmer lover. He was the one who filled the hole left by removing the rusted sunroof, sealed, then painted at a perfect match. I’ve supplied him with a shop manual for the e9. There is a 2800cs on display in their lobby, along with numerous other cars, including an Alpina Z8. As his main job is for Thunder Bunny Racing, the wait time is a little longer than average. I have no affiliation with him, but am passing on this info for members.
 
Thanks. If necessary it should be possible to shorten the factory spacers, thus moving the motor gear closer/in better alignment with the regulator teeth.
 
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