Hi All -
We recently removed the door window glass from our 135i to lose some weight. Most of it was pretty straight forward except for getting the glass off of the cable tracks so it can slide out the top. Okay, first get the door panel off (pry off the press fittings). Raise the window and you can see the attachment points at the bottom of the glass.
You will see a Torx T-20 bolt. That may be an option, but unless you have hardened bits and remember to turn that thing Clockwise to loosen it, don't even thing about it. And then I still wouldn't do it. Ours was way too tight. And you'll see why. Think of a screw and trying to unscrew it from the bottom of the threads. That's what that little torx is. It's on the botton of a bigger bolt on the other side.
If you take a mirror and flashlight and look around to the outboard side of that attachment, what you'll see is this. We took this picture once we had the window out of the car for better visibiliy
That big cogged wheel thing is actually attached to the 5mm hex bolt going through the middle of it. We believe the factory uses a special tool to grab the cogs of that wheel and really get some torque on that thing to keep the window nice and tight (no glass rattling).
Well, maybe we would happen the right tool or can make one, but it's easy enough to take a flat punch and a small hammer and tap the wheel to the Counter-clockwise direction (facing the head of the wheel bolt). You may need to adjust the window height to give your hands more room.
Give some taps and it should loosen it up enough for a regular 5mm hex wrench to work. Once you get the wheel out, you'll feel the plastic clip that the glass sits in.
Feel for the tab at the top and pull it away from the glass (you should be able to do it with your finger) and lift the glass out of the holder on each end. Then slide the window out of the door.