Over time, a rear view mirror can loosen from the windshield because of constant adjusting of the mirror, bumping and weakening of the adhesive. In that event, there's no need to hire a professional. Gluing a mirror back to the windshield is a simple job that can be done quickly and inexpensively.
On the outer side of the windshield, mark the spot where your mirror was attached on the inner side. Use a grease pencil or dry erase marker to trace around the old glue line. This will help you reattach the mirror in the right spot.
Inside the car, use a razor blade to scrape away the old adhesive from both the windshield and the mirror mount. Clean both surfaces with rubbing alcohol, vinegar or any regular glass cleaner.
Remove the mirror from the mounting button by undoing the lockscrew. You might need an Allen wrench or screwdriver to do this.
It's important that the windshield be warm when re-attaching the mirror. If the glass is cold because of cold weather, turn on the heater or defroster to warm it up.
Because you'll be working with adhesive and chemicals, open the windows for good ventilation. Follow the manufacturer’s instructions to open and apply the activator chemicals or “primer” to the mounting spot on your windshield. It might require some drying time before proceeding, so check the package.
Open the adhesive from your kit and follow the manufacturer’s directions to apply it to the base or mounting button. Making sure the mounting button is correctly aligned, firmly press it onto the windshield at the spot with the primer.
Hold the base or mounting button to the windshield for as long as the manufacturer suggests. Be careful not to get the glue on your fingers.
Allow the adhesive to dry for at least as long as the manufacturer suggests. Reattach the mirror to the mounting button.
