Most vehicles come with a prismatic rear view mirror that can be dimmed for day or night manually. A small lever is toggled to change the setting from a day position to a night position. The glass that is used on the mirror is not flat but curved, with the bottom part thinner than the top portion. When the prismatic mirror is on the day position, the image that can be seen from it is reflected off the silver surface that can be found at the back of the glass.
When it is in a night position, the glass is tilted slightly upward, thus letting the surface of the mirror give the reflective image. What you see is still dark but enough for you to check on what is going on behind you. Although this kind of mirror may be high tech, it is still subject to the damage, wear, and tear of everyday use like an ordinary mirror. If you find your rear view mirror suddenly lying on your center console, do not panic, as you can fix it yourself.
Step 1 - Remove the Mirror Mount
A metal part is used to mount the rear view mirror to the windshield, and it is typically secured in place with a star wrench. There are vehicles though where you will need to remove it with a screwdriver or an Allen wrench.
Step 2 - Clean the Mounting
To clean the metal mount of all the old glue, scrape its surface with the use of a metal scraper. If you cannot scrape it off with the tool, use sandpaper.
Step 3 - Mark the Mounting Position
To line up the metal mounting with its original position, line it up with the glue residue that is left on the windshield. You can then trace the metal mount with the use of a black marker. Allow it to dry before going on with the project.
Step 4 - Clean the Windshield
To remove traces of the old glue from the windshield, scrape it off with the metal scraper. Avoid scraping on the mark you made with the black marker. Clean off any residues with the use of the glass cleaner, again avoiding the black marker.
Step 5 - Secure the Metal Mount
Install the metal mounting on the windshield with the use of a glue. Usually, you just have to hold the metal to the glass windshield for a few minutes, but to be safe, refer to the instructions printed on the glue label.
Step 6 - Wipe Off the Black Marker
Once the glue hardens and the metal mount is securely in place, clean off the black marker from the windshield. You should be able to do it easily, but if you cannot, use naphtha instead.
Step 7 - Mount the Rear View Mirror
You can now mount your prismatic rear view mirror unto the metal piece. You can use the old metal mount in mounting a new mirror. When replacing the rear view mirror, be sure to park your car in a garage or shade. If it is hot, the glue will not adhere properly.