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Old 10-26-2012, 09:37 PM
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bluebee bluebee is offline
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Originally Posted by MatWiz View Post
I am telling you that this is the tensioning mechanism.
Thanks. Too bad I didn't know this before I took it apart - but - let's try to document its function moving forward so that the NEXT person benefits.

Originally Posted by MatWiz View Post
it has been such a long time.
I understand. Your DIY thread was posted in 2007!

Originally Posted by MatWiz View Post
the ribs are angled ... like an arrow. Can you see that?
Yes. And, empirically, I think it was much harder to pound the adjuster post inward (into the motor) than it was to simply pull it out (out of the motor).

The strange thing is you'd expect the exact opposite!

That is, the spring tension is clearly placing a force on the head of the ribbed adjuster post such that there is tension pulling it OUT of the motor - yet - it seems to stay in place (probably due to the design of the white plastic 'catch' inside the white motor tube?).

So, for whatever reason ... the post is not supposed to go into the motor as easily as it's supposed to be pulled out.

Given that pushing it in apparently decreases cable tension, that would mean that it's designed to allow an INCREASE in cable tension - but not a decrease.

Maybe it's a cable-stretch compensator?

Originally Posted by MatWiz View Post
That's why I said that once it moves out one rib, it can not move back. The spring and the angle of the rib prevent it from moving in. And that is the self adjusting mechanism. It keeps the cable tight on the rollers.
Ah! So it 'is' a cable-stretch compensator. It's a self-adjusting tensioner of sorts!

Originally Posted by MatWiz View Post
You can't lock it in place. It is designed that the spring gives it the desired tension, and if and when the cable loosen up in time, the spring moves the black piece out a rib, and keeps the tension.
I see. It is adjusted in one place, and then, as cable tension slackens, it's pulled out a notch, to take up the slack in the cable.

If that's the case, then pushing it in a few notches should LOOSEN the cable. Right?

Originally Posted by MatWiz View Post
Practice makes it easier...
I think I'm getting way too much practice on this BMW window regulator!

Thanks for your help. You put a lot of the puzzle together (are you an engineer?).

Here is a photo of the regulator when I pulled it out of the door.
Notice that the cable tensioner was almost all the way in at that time.
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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 09:38 PM.
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