Bimmerfest - BMW Forums - View Single Post - How do we loosen tension on a BMW E39 front window regulator anyway?
View Single Post
Old 10-25-2012, 08:55 PM
bluebee's Avatar
bluebee bluebee is offline
Seek to understand,^Value
Location: San Jose, California
Join Date: Mar 2008
Posts: 25,236
Mein Auto: 02 BMW 525i M54 auto 130K
Originally Posted by dvsgene View Post
did the cable just come off while in operation?
The cable came off in testing - but I don't think it was due to the chipped roller; I think it was because I had not tightened everything - and/or because the window was out of adjustment, as there is not a well defined procedure (despite the Bentleys, which are worse than confusing) for adequate adjustment of the stops.

BTW, I pulled out the square plastic bolt - but it doesn't seem to be of any benefit in loosening the tension. All it does is plug the hole, perhaps so that we can add grease to the motor helical gear.

At some point (I don't know when), the smaller springed tube fell out of its slot in the motor housing.

In hindsight, here is how that tube 'should' have been reassembled:

Another mistake I made (of many) was to not realize that this ribbed black plastic spring-tension adjuster might be a critical component in loosening cable tension!

I should at least have marked the initial location of the black plastic large spring stop, so that I would know how much to push it back into the motor when I put it back.
Here is that black plastic ribbed spring stop, almost pulled out:

I spent some time trying to figure out how that larger black plastic stop goes into the motor - and finally concluded it's a press fit - which takes a LOT of force to fit inward - and which is mighty hard to perform with that heavy spring in place (more about how to conquer that all-important heavy spring comes later).


While I was examining the motor for how to release tension, curiosity got the better of me.

This gear is what spins the coils of cable.

Notice each coil is wrapped around the takeup spool twice, in opposite directions.
The large spring cable is coming in from the left; the smaller spring cable comes in from the right.

Within seconds of snapping that photo for you, as I put the camera down, that nice arrangement of cable coils literally unwound in my hands.

Leaving me with an unsprung front window regulator takeup spool.

After all this - I belatedly realized (what might be) the trick to reduce tension on the front window regulator!
Look at this picture below.

Notice you can easily unhook the heavy coil spring from the cable, and hook it back up easily after the fact, simply by unwrapping it from the wire as you would unhook a key from a common keychain.

I'm guessing this spring unwrapping can be performed without disassembling anything!

If so, that's the trick to releasing tension (WITHOUT DISASSEMBLING ANYTHING!)

It's too late for me to try this trick - but - if I had known that I could simply unwrap the heavy coil spring, I would have tried that, instead of ending up with motor parts all over the place.
Attached Thumbnails
Click image for larger version

Name:	bmw_e39_front_driver_window_regulator_square_plastic.jpg
Views:	3145
Size:	16.9 KB
ID:	347417   Click image for larger version

Name:	bmw_e39_front_driver_window_regulator_spring_stop.jpg
Views:	3130
Size:	18.6 KB
ID:	347418   Click image for larger version

Name:	bmw_e39_front_driver_window_regulator_small_spring_stop.JPG
Views:	3138
Size:	29.3 KB
ID:	347419   Click image for larger version

Name:	bmw_e39_front_driver_window_regulator_small_cable_tube.jpg
Views:	3478
Size:	23.8 KB
ID:	347420   Click image for larger version

Name:	bmw_e39_front_driver_window_regulator__loosen_tension.jpg
Views:	3091
Size:	28.3 KB
ID:	347422  

Click image for larger version

Name:	bmw_e39_front_driver_window_regulator_winding1.jpg
Views:	3144
Size:	111.2 KB
ID:	347425   Click image for larger version

Name:	bmw_e39_front_driver_window_regulator_winding2.jpg
Views:	3145
Size:	99.8 KB
ID:	347426   Click image for larger version

Name:	bmw_e39_front_driver_window_regulator_winding3.jpg
Views:	4357
Size:	109.2 KB
ID:	347427   Click image for larger version

Name:	bmw_e39_front_driver_window_regulator_winding4.jpg
Views:	3276
Size:	114.8 KB
ID:	347428   Click image for larger version

Name:	bmw_e39_front_driver_window_regulator_winding5.jpg
Views:	3283
Size:	114.4 KB
ID:	347429  

Click image for larger version

Name:	trick_to_remove_tension.jpg
Views:	3076
Size:	17.1 KB
ID:	347430  
Please read the suggested threads and add value, either by pictures or by descriptions, so the next person stands on your shoulders.
See also: E39 Bestlinks & How to easily find what you need

Last edited by bluebee; 10-26-2012 at 05:38 PM.
Reply With Quote