Topic: Having trouble gluing the mirror to the windshield

[RoyceP]

I bought a new Carlite windshield for my 68. Like all 68 - and up Mustangs / Cougars the mirror button glues to the windshield. I started out by laying out where the center of the windshield is, and attempted to place a piece of masking tape there to make a mark. The masking tape would not stick! I cleaned it first with lacquer thinner. No good, tape still would not stick. Then I tried Goof Off. Better results, now tape will stick. I used the Goof off to clean the area where the mirror button goes, because tape would not stick there either. Finally it - whatever the residue was - seemed to be gone. I followed the directions on the windshield mirror adhesive, using the primer / activator first, then waiting 60 seconds, applying one drop of adhesive to the button, and holding it in place for another 60 seconds.

All seemed good. I waited until the next day and installed the rear view mirror.

Two days later I am working in the garage and I hear a clunk inside the car. The mirror was laying on the console, undamaged thankfully. The windshield had no signs of adhesive remaining. The mirror button has the adhesive stuck to it.

Anyone else had this problem? What fixed it? I am out of ideas.

[carlite65]

i use rubbing alcohol to clean both surfaces. i also tape the button to the glass overnight.

[bgp429]

I have tried the DIY kits, they don't seem to work as well as the bulk glue the window shops use. Around here they usually will do it for free or minimal cost.

[JKWilson]

I can finally offer some help with something I have a ton of experience at! I use only the Permatex brand adhesive. You can find it at most box auto parts stores. Others may have had luck with other brands but I've had 100% success with so I've stuck with it (no pun intended!).

First off cleanliness is utmost. I determine where the mirror mount will go and then with a grease pencil or masking tape mark the area on the outside of the glass. Make sure your marks are level at the top of the location. Wet the area inside the windshield where the mount is going with alcohol. While wet, scrape the glass with a single edge razor blade (just like your taking off a decal or sticker). Go over it several times. Wet it again with alcohol and wipe off with a lint free rag or paper towel (I use paper towels). Next use a fine to medium coarse file and lay the mount on it (mounting surface against the file). Run the mount across the file several times. You don't need to bear down on it. Check the mount and insure it's level and the entire surface was filed. This exposes fresh material and if it's a used mount it removes the old adhesive. If all is well wash it thoroughly with alcohol. Don't let anything contact the mount surface (keep ya greasy fingers off!).

Now apply the activator to the glass. Permatex used to supply it in a tube that had a glass vial inside with a swab on the end. You crushed the tube, shook it to saturate the swab and then applied it to the glass. They seemed to have changed several years ago and now supply a towelette. I found it works just as good. Apply the activator to completely cover the area of the glass where the mount will go. If you go beyond the area don't worry. The excess can be cleaned with glass cleaner. Now apply the adhesive to the mount. A little goes a long way. There is no need to completely cover the mount surface. When it's placed against the glass it will squeeze out across the surface. Too much and it will squeeze out the sides and dry on the glass. Too little and the mount won't hold properly. It's not an instant set adhesive so you can move the mount slightly. Line it up with your marks you made, stick to the glass and press down. A helper outside can advise if the adhesive spread fully across the mount. Hold it in place for at least several minutes. The warmer the glass, the quicker it sets. Once stuck if you're uncomfortable you can place tape across it. I have never had to do this. DO NOT put the mirror on the mount yet. I have always let the mount fully harden for a day before putting anything on it. I have never had one fail following these steps.

I have mounted mirrors, police radar antennas and video cameras using these steps. The only time anything came off is because the item on the mount was accidentally struck. The mount didn't fail though....it actually took the windshield glass with it! Good luck!

[196667Bob]

++1

Bob (also from experience with same Permatex product)

[carlite65]

that is what i do also, although his explanation is much more detailed. it has produced good results.

[Chris Thauberger]

This is what was used in the body shop for decades. Used to be called MinuteBond but was bought out by Loctite.

This is the full size kit (50.00) and will do hundreds of mirrors. They make a smaller one for about 30.00.

Expensive, but has never failed me.



Chris

[RoyceP]

Thank you all for the comments. I did use the Permatex kit. I did mark it on the outside as the shop manual says. I taped the inside in case there was any excess adhesive - that turned out to be unnecessary but it still seems weird that tape won't stick to the inside of the windshield but not the outside. I will try the razor blade and alcohol, that's about the only thing I can see suggested that I did not already do. I've done this dozens of times over the years and never had this problem previously.