How permanent are you looking for? you can get epoxy that can do it but you normally need to rough up the surfaces of both objects to get things to stick properly. you can get some 2 part epoxy for like 5$ at any auto parts store.

 

im looking for 100% permanent
i'll look again to see if i can find something like that, i just dont want to waste my money if it's gonna fail within a few hours of putting the mirror up after the glue has set

 

Like i said if it does not stick its more then likely improper surface prep. Most things cant stick to something that is completely smooth. the plastic is easy to rough up but the windshield will be a bit more difficult.

 

have you tried... rearview mirror glue?

 

yes i have. as i stated in the op, ive tried the rearview mirror kits from the local auto store, they dont work and specifically say they are made to used on metal

 

Not to ask a stupid question. But is there any other way to mount it?

I thought I've seen some that looked like they mounted in the headliner.

 

Check a local marine supply store. I'm sure they'd have something. If they can stick something to the bottom of a boat in saltwater, I'm sure it can hold onto glass.

example:http://epoxieszvyjrz.blogspot.com/2012/08/loctite-1405604-085-ounce-plastic.html

 

Which part comes off? The glass end or the plastic end?

 

The glass I'm sure. I sold those windshield mirror mount kits all day long, most people do not have the patience to install them correctly. They are not a form of silicone, rather an ester resin of some sort. Your skills are the problem, the kits work for years if done right. If the plastic is an oily base plastic or flexible, bendable, it will not hold either, choice of plastic used there is a problem. The key to making windshield kit work is to clean BETTER THAN PERFECT, perfect is not good enough there. Then figure out some way of positively holding the part in one EXACT place while the glue cures. That glue is cranky as shi-, it will fail if the part is moved even so much as a few thousandths of an inch. The glue is forming bonds that if the part is moved will shear internally to fail shortly. A shaky hand doesn't have a prayer of installing using it. I always taped part down hard so it can't move. I've got a 250cc. bottle of the Loctite branded stuff (cost back then around $300!) from 35 years ago, it still works like gangbusters as long as I do my part right. Really quirky stuff, it drives people crazy because they can't make it work. We had hell back then too, Loctite had to give classes to train how to use it.

Windshield is safety glass and tempered to crack with a thought, if you were successful in sanding it you just ruined your windshield as safety glass just loves to crack at stress risers (grooves), which is what sanding work leaves behind. One should NEVER sand on windshield or side window glass...................

 

where were you when i was first trying to install this lol. i dont understand why one side has stayed and the other is having such big issues. to address some of the other questions, the kit came with the things required to attach the mirror to a roll cage, but i only have the rear section of a cage, a roll bar. the part that comes off is where the plastic button attaches to the windshield (glass). i tried a different glue from my local Sears hardware and that ended up melting the section of my windshield that i used it on. i think the combination of the different adhesives had a chemical reaction? idk what to do now

 

every wink mirror I've seen in person was mounted using hardware to slip unerneath the mounts for the sunvisors, basically using the same screws being pinched between the visor and headliner.

 

Is windshield glass? Glass does not melt.................

 

it has a plastic compound melted into it when it's being made....hence safety glass.

 

The plastic is in a thin layer between two sheets of true glass, glass cannot be made with plastic mixed in it.

Meaning the glue cannot get to the plastic unless a crack through one side of a glass layer.

The glass is tempered by heat to explode upon impact into small rounded fragments just like on side glasses but the glue/plastic layer holds the broken windshield fragment matrix somewhat together.