Replacement of day/night mirror glass

[RDJ]

The glass in my rearview mirror in my 67 Barracuda is really bad. It has a day/night switch on the bottom. I can barely see anything with it. I have a similar one which I can use, but the glass is still not great, and I would like to keep the original.

I asked a local glass shop guy if he could replace the glass in it. He said he could replace it, but the day/night function would not work. I'm not sure why.

Is there somebody out there that can replace the glass in a day/night mirror and have it function as intended?

Does anybody know why the glass is special? I jut thought the switch changed the angle of the mirror.

 

[RDJ]

By the way, if somebody has a mirror with good glass and a day night switch of a similar year, let me know. I don't need the post/mounting part, just the bottom part with the glass that is held on by an allen type screw.

 

[slantsixdan]

The glass in a day/night mirror is wedge shaped in cross section; the front and back aren't parallel as in a normal sheet of glass or mirror. In the "day" position you are looking through the front surface at the reflection off the silvering on the back surface. In the "night" position the silvered back surface is pointing up at the dome light so you can't see it from where you're sitting, and the dim reflection you're seeing is off the front surface of the mirror glass. The wedge-shaped glass isn't available as a repair part. But day/night rearview mirrors in good used condition are not hard to find.