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Old 02-11-2013, 02:35 AM
Piston_broke's Avatar
Piston_broke Piston_broke is offline
What was that noise??
Location: Gold Coast, Australia
Join Date: Aug 2008
Posts: 307
Mein Auto: E28 M535i, E30 323i
Hi, not heaps but some info spread around the interwebs on this topic.
The rear windows, from what I know are designed to move (close) slower than the front. But not that slow where they creep up.
Several issues need to be addressed in order to cover all culprits.

1/ Sticky Regulators.
Remove the door cards and vapour barrier after you read this: and then remove (with a degreaser) what will appear to be gunked up factory issue grease from the regulators.
Apparently it gets quite gluggy and solidifies to a point over time. Remember you are dealing with a 30 year old car.

Then regrease all pivot points and moving parts on the reg with lithium grease. This is a light duty grease typically colored white which is also used on door hinges, hood hinges & latch etc. I remember also reading where it was recommended to use a teflon spray. The main point here is to remove the old grease, clean and replace it.

2/ Window Switches.
Also if you haven't done it, you should pull the switch units out from the centre console and polish up the contacts which can deteriorate over time. Take a read of this, take it easy and don't break anything:

3/ Window door guide rubber with felt guide.
After completing the above two steps and you still have no luck (unlikely) then you may want to r & r the door felt guides:

GL and report back and let us know how you went resolving this pain in the butt problem.

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