Best sealant for affixing replacement mirror glass to car mirror

Factual Questions
1

3 weeks ago the mirror glass fell out of the passenger’s side mirror on my Nissan 300ZX, yes the same one in my avatar. I was just driving along and looked at my mirror and one minute it was there and I turn my head for a second and then it’s gone. I look back at the side of the road and there it is in a million pieces - fuck! I ordered a replacement glass, which arrived 2 days later. It fit perfectly and came with 4 large adhesive pads, which I stuck on the back and pressed to the plastic backing inside the mirror housing - quite firmly and making sure it was well adhered.

Or so I thought. Only a few days later the same damn thing happened again.

I ordered a SECOND replacement glass. But this time, screw the adhesives; they clearly didn’t do their job. I’m gluing the damn thing in there this time. The question is, what glue is the best? Epoxy? Some kind of rubber or silicone sealant? The ol’ double-barrel quick-set epoxy tube is my go-to for fixing shit that breaks, it usually works for almost anything. But epoxy sets rigid and gets brittle and that seems like maybe not the best choice for something that’s going to be vibrating and shaking like a mirror on a car - maybe I want something with some flex to it. But what’s the best thing that can combine that with a STRONG hold so the damn thing never falls out again?

2

I’d use Silicone.

3

Ditto. Clean the plastic carrier first, scrape off any old adhesive. Make sure the mirror is sealed around the edges.

I had to do it after a meteor cracked my car mirror*.

*No I can’t prove it was a meteor, but there is a slightly better chance that it was a meteor because a large one hit nearby at approximately the same time.

4

Sugru. Very happy with my experiences with the stuff.

5

In addition to shaking, which I assume the epoxy should be able to handle, the mirror will probably expand and contract at a different rate than the plastic housing surrounding it, and that is what would probably do you in. I would consider a silicone-based adhesive for this. Clean both surfaces VERY WELL before applying and it should work well.

6

The silicone sealer sold in aquarium stores works well. Triple dittoes on the pre-cleaning advice.

7

Thanks for the help !

8

As this is your 3rd try at this, I wonder if gluing is sufficient?

I’d consider adding some mechanical support to this. Could you find a plastic U-channel that could be glued to the backing piece, and would fit on the bottom to hold both the mirror & the backing piece? That would cover 1/8 -1/4 inch at the bottom of the mirror, but that’s not much. And a physical holder like this would be sturdier.