Window Motor R&R
03-21-2009, 10:11 AM
#1
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Thread Starter
Window Motor R&R
Window motors are now only available from Porsche at $300 a pop.
This is to give you an idea about how you can rebuild your existing window motor.
Now, this far from as comprehensive as Dwayne's write-ups, but it will give you an idea of what's involved.
It's not so bad. I will leave the getting to the window motor up to you.
Once you have it in your hands, it's easy to disassemble with 2 torx bolts holding the motor to the transmission.
- Give the motor bits a good cleaning with some Electromotive spray and a brass wire brush.
- Check all the solder connections to make sure there still intact.
You may decide to re-flow the connections, I did not as they looked in good shape.
-Clean all the cruddy grease around the transmission gear
(not much to clean inside unless as the transmission housing can't be separated easily.)
- Re-lube gear. I eased the gear up with WD-40, which helped loosen the sticky gear,
then coated the base of the gear with lithium gease.
-I found water a made it's way into the motor. There is a gasket there, but not around the main 2-pin connector.
I applied RTV around the there and on the gasket.
Plugged it back in and it worked. Funny thing is I had already bought a new one, so this was an exercise in exploration.
So I figure I would make it worth my while and share.
Now, your experience may not be the same, but it's worth checking into before buying a new motor. Wish I did.
Actually I got luck and bought the last one from Autohaus AZ for $100.
Also, there are companies out there that do rebuild these, so that may be another approach.
Hope this helps....
This is to give you an idea about how you can rebuild your existing window motor.
Now, this far from as comprehensive as Dwayne's write-ups, but it will give you an idea of what's involved.
It's not so bad. I will leave the getting to the window motor up to you.
Once you have it in your hands, it's easy to disassemble with 2 torx bolts holding the motor to the transmission.
- Give the motor bits a good cleaning with some Electromotive spray and a brass wire brush.
- Check all the solder connections to make sure there still intact.
You may decide to re-flow the connections, I did not as they looked in good shape.
-Clean all the cruddy grease around the transmission gear
(not much to clean inside unless as the transmission housing can't be separated easily.)
- Re-lube gear. I eased the gear up with WD-40, which helped loosen the sticky gear,
then coated the base of the gear with lithium gease.
-I found water a made it's way into the motor. There is a gasket there, but not around the main 2-pin connector.
I applied RTV around the there and on the gasket.
Plugged it back in and it worked. Funny thing is I had already bought a new one, so this was an exercise in exploration.
So I figure I would make it worth my while and share.
Now, your experience may not be the same, but it's worth checking into before buying a new motor. Wish I did.
Actually I got luck and bought the last one from Autohaus AZ for $100.
Also, there are companies out there that do rebuild these, so that may be another approach.
Hope this helps....
03-21-2009, 10:21 AM
#2
Rennlist Member
Rennlist Site Sponsor
Cleaning and lubricating the window motor and gearbox is a good thing.
I have had two different window motor problems on my '86S. On one side, the motor windings were not making good contact with the commutator segments on the armature. Carefully scrape the wire next to the bent-over piece, and apply a tiny drop of solder. Do every connection, being careful not to short two together. No cost to fix, takes two hours total.
The other problem was a little more interesting. I assumed that it would be the same as the drivers side problem, but after I soldered the wires, it still didn't work. A little troubleshooting revealed that the motor has a tiny thermal protection device in the end of the motor. If you are getting power to one connection on the end bell (the molded plastic end of the motor), but not to the brushes, this may be the problem. There is a little black block that is inserted into the end bell. Unsolder it and pry it out. Take a razor knife, and carefully cut around the base to remove the cover. Using very fine sandpaper, clean the contacts, and adjust them so that you get electrical continuity through the contacts. Reassembly is the reverse of disassembly. Again, no cost.
WYAIT, clean and lubricate the rest of the window lift mechanism as well. This will help speed the operation quite a bit.
You might also want to tighten the central tube sliders to reduce rattling. If you don't have replacement parts, you can take care of the problem for a year or two by putting nylon wire ties around the slider to take up the wear.
I have had two different window motor problems on my '86S. On one side, the motor windings were not making good contact with the commutator segments on the armature. Carefully scrape the wire next to the bent-over piece, and apply a tiny drop of solder. Do every connection, being careful not to short two together. No cost to fix, takes two hours total.
The other problem was a little more interesting. I assumed that it would be the same as the drivers side problem, but after I soldered the wires, it still didn't work. A little troubleshooting revealed that the motor has a tiny thermal protection device in the end of the motor. If you are getting power to one connection on the end bell (the molded plastic end of the motor), but not to the brushes, this may be the problem. There is a little black block that is inserted into the end bell. Unsolder it and pry it out. Take a razor knife, and carefully cut around the base to remove the cover. Using very fine sandpaper, clean the contacts, and adjust them so that you get electrical continuity through the contacts. Reassembly is the reverse of disassembly. Again, no cost.
WYAIT, clean and lubricate the rest of the window lift mechanism as well. This will help speed the operation quite a bit.
You might also want to tighten the central tube sliders to reduce rattling. If you don't have replacement parts, you can take care of the problem for a year or two by putting nylon wire ties around the slider to take up the wear.
03-21-2009, 11:02 AM
#4
Rennlist Member
Thread Starter
Cleaning and lubricating the window motor and gearbox is a good thing.
I have had two different window motor problems on my '86S. On one side, the motor windings were not making good contact with the commutator segments on the armature. Carefully scrape the wire next to the bent-over piece, and apply a tiny drop of solder. Do every connection, being careful not to short two together. No cost to fix, takes two hours total.
The other problem was a little more interesting. I assumed that it would be the same as the drivers side problem, but after I soldered the wires, it still didn't work. A little troubleshooting revealed that the motor has a tiny thermal protection device in the end of the motor. If you are getting power to one connection on the end bell (the molded plastic end of the motor), but not to the brushes, this may be the problem. There is a little black block that is inserted into the end bell. Unsolder it and pry it out. Take a razor knife, and carefully cut around the base to remove the cover. Using very fine sandpaper, clean the contacts, and adjust them so that you get electrical continuity through the contacts. Reassembly is the reverse of disassembly. Again, no cost.
WYAIT, clean and lubricate the rest of the window lift mechanism as well. This will help speed the operation quite a bit.
You might also want to tighten the central tube sliders to reduce rattling. If you don't have replacement parts, you can take care of the problem for a year or two by putting nylon wire ties around the slider to take up the wear.
I have had two different window motor problems on my '86S. On one side, the motor windings were not making good contact with the commutator segments on the armature. Carefully scrape the wire next to the bent-over piece, and apply a tiny drop of solder. Do every connection, being careful not to short two together. No cost to fix, takes two hours total.
The other problem was a little more interesting. I assumed that it would be the same as the drivers side problem, but after I soldered the wires, it still didn't work. A little troubleshooting revealed that the motor has a tiny thermal protection device in the end of the motor. If you are getting power to one connection on the end bell (the molded plastic end of the motor), but not to the brushes, this may be the problem. There is a little black block that is inserted into the end bell. Unsolder it and pry it out. Take a razor knife, and carefully cut around the base to remove the cover. Using very fine sandpaper, clean the contacts, and adjust them so that you get electrical continuity through the contacts. Reassembly is the reverse of disassembly. Again, no cost.
WYAIT, clean and lubricate the rest of the window lift mechanism as well. This will help speed the operation quite a bit.
You might also want to tighten the central tube sliders to reduce rattling. If you don't have replacement parts, you can take care of the problem for a year or two by putting nylon wire ties around the slider to take up the wear.
03-21-2009, 11:51 AM
#5
Jim,
Great write up. It would be nice if this list had a "how to" folder where posts like this would always stay at the top. One thing that did catch my eye was the use of RTV around electrical contacts. I always heard that the evaporating acetic acid in the RTV could corrode the near contacts.
Dennis
Great write up. It would be nice if this list had a "how to" folder where posts like this would always stay at the top. One thing that did catch my eye was the use of RTV around electrical contacts. I always heard that the evaporating acetic acid in the RTV could corrode the near contacts.
Dennis
05-11-2009, 07:47 PM
#6
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Dennis,
This list DOES need a how-to folder. Check out this link: http://www.e38.org/ It's my first stop when doing anything to my 740 and it saves alot of searching. The drivers motor on Carli is no longer working. I can hear a clunck in the door when the switch is actuated.............probably the motor?
David
This list DOES need a how-to folder. Check out this link: http://www.e38.org/ It's my first stop when doing anything to my 740 and it saves alot of searching. The drivers motor on Carli is no longer working. I can hear a clunck in the door when the switch is actuated.............probably the motor?
David
05-11-2009, 09:11 PM
#7
David,
The clunck may the motor trying to work but the gear lubricant is locking it. This happened on my 78. When I opened the gear case, the grease had hardened into plastic like chips.
Dennis
The clunck may the motor trying to work but the gear lubricant is locking it. This happened on my 78. When I opened the gear case, the grease had hardened into plastic like chips.
Dennis
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05-11-2009, 11:10 PM
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Dennis,
You may very well be right. There is a current draw when the switch is activated (door panel light dims). I'm going to yard the motor out tomorrow and take a peak. So it is possible to open and clean the gearbox? I wonder if the slow moving wipers have the same gearbox problem..........any suggestions?
David
You may very well be right. There is a current draw when the switch is activated (door panel light dims). I'm going to yard the motor out tomorrow and take a peak. So it is possible to open and clean the gearbox? I wonder if the slow moving wipers have the same gearbox problem..........any suggestions?
David
05-12-2009, 09:23 AM
#11
David,
IIRC the early versions had three screws to remove the journal side of the gearbox. I was able to clean mine out and replace the grease chunks without removing the motor.
Dennis
IIRC the early versions had three screws to remove the journal side of the gearbox. I was able to clean mine out and replace the grease chunks without removing the motor.
Dennis
05-12-2009, 09:27 AM
#12
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Rennlist already has a DIY forum for collecting all this stuff in one place. 
https://rennlist.com/forums/928-134/
https://rennlist.com/forums/928-134/
05-12-2009, 10:11 AM
#13
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Thanks for the write-up and pics. Great stuff!
Just one of the reasons I enjoy working on this car is that most of the mechanisms are actually built to last instead of sealed units made to be used and thrown out.
Just one of the reasons I enjoy working on this car is that most of the mechanisms are actually built to last instead of sealed units made to be used and thrown out.
05-12-2009, 10:13 AM
#14
Rennlist Member
"Rennlist already has a DIY forum for collecting all this stuff in one place. "
Yup, and it is segregated by model type - we shark owners have our own Rennlist DIY forum. Lots of stuff in there. Gretch will need to put this in there too when he gets the chance.
Nice write up Jim!
Yup, and it is segregated by model type - we shark owners have our own Rennlist DIY forum. Lots of stuff in there. Gretch will need to put this in there too when he gets the chance.
Nice write up Jim!
06-15-2011, 07:10 PM
#15
Nordschleife Master
Just saw this linked from another thread.
FYI - from the UK list:
FYI - from the UK list:
The identical Bosch motor was also used on the Saab 900 (79-94) and I've seen these from about £55+vat new. Different badge, different price. The Saab part also lists as 51.821036 and is available from the likes of http://www.twostroke.co.uk (no connection, never used them).
S4 and later have 10 teeth on the cog, so the Saab 900 fits this. I believe the earlier 928's have only 8 teeth.
S4 and later have 10 teeth on the cog, so the Saab 900 fits this. I believe the earlier 928's have only 8 teeth.