HOWTO: Stop the Rear View Mirror From Rattling

It's been annoying me for years so I finally got around to doing something about it.

I'm sure most people with a lower engine mount or lots of bass will know what I'm talking about. The rear view mirror just seems to resonate now and then and make the worst rattling noise of the whole interior.

I finally got sick of it and took it off, thinking I could pop it open and put some foam or something in it to damp the vibrations. What I didn't realize is that it's completely sealed so there's really no way to get inside it. The only openings are around the edges of the reflectors where the map light bulbs are.

So I looked at it and shook it and tried to figure out what was making all the noise. I thought it might be the light housings but they're in there pretty tight. I thought it might be the bulbs themselves, but the seemed pretty snug as well. Shaking the thing around, I figured out that the mirror glass itself had just a little bit of play. I got a strip of foam, slightly thicker than double-sided tape. I used my finger to pry the top edge of the plastic away from the glass just enough to make a little gap that I could slip the foam in there.

Letting go, the foam was jammed solidly in place. I used a utility knife to trim away the foam left outside the housing and that was that.

The top of the mirror looks like it has a very slight peak now in the middle, and there's no more rattling. I guess if you use a wider piece of foam, you won't get the little peak, but it's barely noticable.

AND NO MORE RATTLING.