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DIY: Coupe Window Regulator Adjustment

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  • DIY: Coupe Window Regulator Adjustment

    Originally posted by ospfbgp on M3F

    (Apologies for picture resolution/size, could not save the pictures directly from the thread. Had to screenshot and crop them.)

    "DIY E46 M3 window regulator adjustment to stop wind noise from a window that is not sealing properly
    I guarantee nothing. This was my experience and try at your own risk. I am not responsible.

    What you need to get started so you can adjust.
    Painters Tape, plastic trim removal set, 1/4 drive ratchet and 2-3 inch extension, e-torx 5, t-25 torx, 13mm socket

    1. Tape parallel on the top and bottom of the outside molding on the door and get a plastic trim removal tool and start prying from back to front or front to back. I found I needed to pry a little on top and then bottom and work my way to the end of the door. Mine came off very easily. Once this is removed you will see some holes and I call these holes m1 and m2 in picture 1.

    2. Now look under the door and you will see 2 rubber plugs. One in front and one in the rear. Remove these plugs and put them in a safe place. I call these holes b1 and b2 in picture 1.

    You are now ready to begin adjusting.

    Picture 1 - Holes in the door that allow you to adjust the window regulator

    Holes b1 and b2 in the bottom of the door and have a black rubber plug filling the holes. In order to adjust b1/b2 you will need to lower the window all the way down and remove the rubber plugs. You will need to insert t-25 torx to adjust. I believe clockwise will raise the window on the regulator and counter-clockwise will lower the window on the regulator. Remember when adjusting these you need to count if you make a quarter, half or full turn with your wrench. This way you can set it back to where you started.

    Holes m1 and m2 allow you to release the window from the grip of the regulator so it can be removed or window moved on the regulator from front to rear. I am not sure you will ever have to adjust this very much if you marked your window when you reinstalled it with the new window regulator. In order to adjust the window, you will need to lower the window just past half until the e-torx 5 appears in holes m1 and m2. Clockwise tightens and counterclockwise loosens the grip of the window regulator.

    Close up hole m1 and the e-torx 5

    Hole m2 is the magic hole that allows you to adjust the pretension/drag of the window on the rubber seal. You will need to loosen the etorx on m2. I think 2 turns to 2 1/2 turns on the etorx. Once you have done this carefully insert your 13 mm socket and turn that nut to the right. The most the nut will turn will be 1/4 turn. 1/4 turn will adjust the wedge and give you maximum pretension. When you turn the nut to the right it will drive a wedge up and create more pretension/drag on the rubber seal. There is a special tool they reference in the Bentley Manual and BMW TIS for this but I have never seen the tool. I would like to have it but I do not know the cost. I think the tool would allow one to make a much finer adjustment on the drag/pretension.

    Hint: When adjusting a window go to the other side and check and see how it is. This will be a good reference if you have a window that has a nice tight seal. I suggest you try and replicate the way it seals.

    Picture 2 - My window leaked at the red area and caused me to write this DIY

    My window leaked at the red area above. I had purchased my m3 from an individual in Dec. 2009. On the way home with the car, I noticed the window was leaking air at the area in red on picture 2 and it was driving me crazy. So here is what I did to fix it.

    Problem 1 - hole b2 had been adjusted to push too tightly up on the seal towards the top of the car. When the window closed it would torque and bow the window out a little in the red area. I adjusted b2 so it did not push/torque or bow when it automatically seals when you close the door. After monkeying with this I still had some wind noise but not near as much. My advice is to adjust this so it is not pushing at all and if it does push must not bow or torque the window out in the red area. You can observe this with your eyes.

    Problem 2 - The pretension or drag was not allowing the window to seal properly at the red area in picture 2. I also noticed if I would close the door to one click and pull tightly on the door that the top of the window on picture 3 in green would not touch the seal. I think that the window at the top on the green area must touch the seal for you to get an airtight fit.

    Picture 3 - Pretension/Drag on rubber seal w/ door closed and pulled tight to 1 click

    Picture 4 - Proper sealing inside of the car

    Notice in picture 4 the area in red. I had a problem with this area on my passenger side that was caused by me trying to learn how the window adjust. I did not notice it until I road on the passenger side. I had adjusted b1/b2 but did not count my turns on b1 and b2 to put it back as I started. So I decided to get in the car and close the door and push on the window with my fingers on the area in red. I moved back and forth and it would push out fairly easily and I could tell it was not sealing. I pulled the plug on b1 and made 1/2 turn adjustment to push the window up. I then felt with my hand and it felt to me like it was not sealing properly. I test drove and it still leaked. I made another 3/4 turn adjustment and it felt very tight now. I test drove and I was leak-free. I then decided to adjust it down 2 turns and felt with my hand. I could tell just with my hand if it was sealing and really did not have to test drive. I suggest once you get the window close at the sealing points you make it so it does leak air. You then start adjusting with 1/2 turns on b1/b2 until you can feel it seal in the channel good. I believe this is the best way to learn how to get the window to seal almost perfectly.

    Hint: If you continue to adjust b1 without adjusting b2 or vice versa you will cause the window to not be equal distance from the B pillar. Look at Picture 5. This is a correctly adjusted window because the gap at the red arrows are equal. I suggest you try and get this equal but do not worry about having a perfect seal yet. Once you get this equal you can then start adjusting b1 and b2 the same amount of turns. So if you move b1 1 turn you must also to b2. This will preserve your correct gap and allow you to slowly get a perfect seal.

    Picture 5 - This is a perfect example of how the gap at the top and bottom are equal.

    Last edited by bran.stum; 03-21-2020, 02:00 PM.