Ok so it sounds like maybe it's all solid supported parts but some things are just very close to each other. They don't touch, but if the whole shell of the door body is vibrating from the speaker, some close parts can touch. Though this video still does not quite explain what or where. But I guess if you just look in that area presumably you'd find it.bkw777,
From the video I couldn't see the foam under the "bracket" either.
The tech says in the video that it was installed under the bracket inside the door panel that ran near the window track. I don't think the "window track" is unsupported, it just happens to be very close the bolts and bracket. Re "touching": maybe the end of the bolts were close enough to the window rail/ track to cause the vibration (?). Possibly, the foam gave the bolts just enough cushion to stops the bolts from vibrating. It would only occur when I had the volume at 35-40 with heavy bass. Even though they don't touch sound waves can do strange things at certain frequencies. These speculations are simply a guess by me.
I can only report that I have had no issues with the bass rattle since the repair was done (almost a month ago). Others have said they have used the video at the dealership, had the repair done, and it has also resolved the problem.
C/G
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