A rear view mirror allows a driver to see what is happening behind the vehicle while driving. It is especially important while parking, maneuvering at slow speeds and changing lanes. Over time, the adhesive bond that connects the rear view mirror to the windshield glass can weaken and the mirror can fall off. Most mirrors can be replaced easily by the home mechanic.
In most cases, when a rear view mirror falls off the windshield, it will leave behind an adhesive residue. Begin by placing a piece of masking tape just above this residue and marking on the tape where the centerline of the mirror was. Then use a flat razor blade to clean the adhesive off the windshield.
The rear view mirror connects to the windshield via a small metal plate at the base of the mirror mount. Find the correct size hex or torx head screwdriver and loosen the screw at the base of the mirror. Note which side was against the windshield. Clean the old adhesive off this side of the metal plate.
Reattaching the Base Plate
Buy a specialty rear view mirror adhesive kit from an auto parts supplier. Most will come with directions and any special precautions for the specific product listed on the back. Work in a well-ventilated area. These adhesives contain toxic chemicals that can be hazardous to humans if inhaled in large quantities. If you are working outside on a cold day, use a hair dryer or heat gun to heat the mounting surfaces. Keep the heat source at least 12 inches away from the windshield. Heating the glass too quickly or too much can cause the glass to crack or shatter. The kit may contain a cleaning agent that must be applied before the glue. If it doesn't, use rubbing alcohol to clean the surfaces. Most rear view mirror adhesive kits contain a two-part epoxy. Mix the two parts together and apply it to the base plate. Use the mark you made on the masking tape to align the base plate, and press the plate onto the glass. Hold the plate for 10 to 15 minutes until the epoxy sets up.
Reattaching the Mirror
Wait at least 10 hours before attempting to mount the mirror on the plate. This will give the epoxy time to harden. Then simply slide the mirror base over the plate and tighten the retaining screw.