There's been plenty of threads, but none as detailed as this one. I'm confident that I have identified the source of our problems and developed a permanent solution.
I "fixed" my window many times before I finally got sick of dealing with it and was on the verge of retrofitting manual windows into my car. Then one day I sat down and thought the whole thing through from the source of the problem to each step of the self destruction process.
I've known people who have taken their cars to the dealers and spent hundreds of dollars to replace regulators and sliders that still give them troubles. As long as your regulator motor still works and the plastic sliders are not broken in half, this repair should be a permanent fix with no replacement parts needed.
Just follow the steps posted in this thread and it shouldn't happen again or atleast for another 10 years if you use the wrong grease. Normal Operation:
The power window assembly is composed of a motor attached to a "scissor" mechanism known as the window regulator which raises and lowers your window upon actuation. Both of the regulator "arms" have plastic "sliders" attached to them via a "ball & socket" which snaps together and is held on by a steel "C" clip. The sliders are coated in grease and slide back and forth in a metal channel which is located on the bottom of the window. The window itself is held in place by forward and aft bow-shaped vertical guide tracks which have felt-lined rubber inserts to absorb shock and allow smooth motion of the window during operation. Self Destruction:
The problem is that when the factory grease used to lubricate the window sliders gets old, it turns into a paste-like substance. This causes one of the sliders to bind, which in turn causes the window to go up or down unevenly. Once the window is tilted, The regulator arms will flex causing the metal ball on the regulator arm to pop out of the plastic slider. This is the first snap that you'll hear.
Then when you operate the window again, the window will only be held on by one slider and the metal ball on the detached regulator arm brushes against the slider track and onto the window glass. This is the crunch that you hear next. The window is now off-track which causes the window to twist inward which in turn tweaks the forward or aft vertical track.
Sometimes, the felt-lined rubber guides that fit into the vertical tracks slide down allowing slop in the window and causing uneven resistance on the window during operation. The Breakdown:
The cold weather contributes to the grease hardening into a pasty substance, this is why it happens more frequently to cars in colder climates. Hence, less Californians and Floridians having window issues. It doesn't mean we're exempt, just prolonged. My car came from Michigan and my window troubles started on day two of my voyage home. It's not so much a bad design as it is a poor choice of grease on BMW's end. It's really embarrassing when it happens to you in a drive-thru The fix:
If you have side-impact air bags, DISCONNECT YOUR BATTERY and wait approximately 30 minutes before starting this procedure. DO NOT reconnect the battery while the airbag is disconnected as this will trigger an SRS light that requires a special tool to reset. To avoid death, serious injury, or damage to the vehicle, NEVER work in the vicinity of an un-deployed airbag. Only after the airbag is completely removed and placed in a safe location away from you and the vehicle, is it safe to perform work on that part of the vehicle. While my intentions are to save you guys money by fixing your own cars, the last thing I want is for someone to get hurt. Let's stay safe guys, your health isn't worth saving a couple bucks!
Step 1: Remove Interior Door Panel
1a) Pry out the power mirror switch(driver's side) or the blanking plate(passenger's side) and disconnect.
Look inside the hole, locate the torx head screw and remove. 1c)
Locate the hole on the bottom of the interior door handle(not the door lever, the actual handle that you grab to close your door). Shine a light up in there and locate the torx screw. It's the same size as the one you removed from behind the mirror switch. 1d)
Remove the trim piece around the door lever by sliding it forward and pull inboard. 1e)
Start to pry the door panel off at one of the top corners and work your way around the panel prying the clips out of the actual door. There's 10 of these. Some may come unglued from the door panel and remain stuck in the door. Don't worry, I'll address this in the next step. 1f)
Unplug the speakers from the back of the door panel. 1g)
Lift upward on the door panel and set it aside.
Step 2: Repair Door Panel Clips 2a)
If the door panel clips happen to come unglued and remain in the door itself, just pull them out of the door. 2b)
Notice that they are numbered. Clip #1 is located by the door lock pin and they go in order around the bottom of the door panel ending with #10 near the mirror. 2c)
Look at the factory glue left behind on the door panel. Compare it with the corresponding clip and determine which side of the clip is up by looking at the imprint of the number left by the clip. 2d)
Mark where each clip goes on the door panel with a sharpie or permanent marker. I wrote down the number along with an arrow pointing which direction the clip goes. I also put a dot on each corner of the rectangular impression in the glue on the door panel to ensure exact placement. 2e)
Remove the old glue using a flathead screwdriver to pry and peel the old glue off. Make sure your marks are still visible to avoid gluing the clips on upside down or in the wrong location. Remember that they have to line up with the holes on the door! 2f)
Use a coarse grit sandpaper and roughen the mating surface of the clips and the door panel. 2g)
Get some "JB Weld" QUICK DRY from your local autoparts store. It's the only thing that works!!! Nothing else will stick to the door panel. 2h)
Mix equal parts bonding agent and hardening agent on a piece of cardboard. Only mix enough to LIBERALLY do one clip at a time as the working time of the JB Weld is very short. 2i)
Verify the number on the clip and the direction in which it goes onto the door panel(<---VERY IMPORTANT!) 2j)
Apply a liberal amount of JB Weld onto the clip and firmly press it onto its corresponding location on the door panel. Be sure to place it in the exact spot as the rectangular imprint on the old glue that you previously removed. 2k)
If you have enough JB Weld left over, mix it up and apply it around the edges of each clip and if possible slightly overlap the flat part of the clip to ensure a nice grip when it hardens. 2L)
Wait atleast an hour or two before reinstalling the door panel. The JB Weld will dry as hard as steel and you shouldn't be able to make an impression in it with your fingernail. Step 3: Remove Insulation/Sound Deadening Foam
Just gently peel it away from the door and place it aside. Be careful not to let the black adhesive putty stick to your interior or clothing. Step 4: Remove Inner Weather Strip
With the window in the completely lowered position, pry and unclip the metal clips holding the rubber strip along the inner edge of the door. Try not to bend these clips, a tiny flathead screwdriver works well.