30 March 2016

3M Window Weld = No good

The sun even shines on a dog's ass some days.  I don't know what that means but I heard it years ago and I like it.

So the tint shop reefed on my passenger side door panel like a bunch of gorillas and I had to remove and replace it.  As luck would have it, this gave me an opportunity to inspect my previous work.  When I serviced the window regulators I used 3M Window Weld to replace the factory butyl tape.  It felt and seemed to be about equivalent to the factory butyl beads and it got good reviews from other BMW owners on Amazon.  Not so, in my experience.  The vapor barrier was un-stuck from the 3M Window Weld, basically rendering the panel useless.  Maybe it is the SC heat or humidity or maybe there is an install trick I didn't know (hard to believe, it is a pretty simple product) or maybe it's just the wrong choice.

I added 3M Weatherstrip adhesive I had in stock instead.  This product is actually a contact cement, so you have to put adhesive on both surfaces to be bonded.  Then wait until it's tacky, then press the surfaces together.  I did not remove the Window Weld from the metal part of the doors as it was really well bonded to the sheet metal, I just glued on top of it and also around it.  Seems like the Window Weld just doesn't like to stick to the foam of the vapor barriers.  The results are very stout.  I have been driving around the last few days without door panels (I re-did the driver's side too) and the vapor barriers still pass my pull tests.  Complete removal may not go so well for the vapor barriers (they may need replacement at that time) but the seal is fantastic.  So, lesson learned.  Don't use Window Weld.  Do use Weatherstrip Adhesive.  Maybe the broken door panel was a blessing in disguise, as I would have eventually had water intrusion and or damage from un-stuck vapor barriers.

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