Does the image in your external mirror wobble or vibrate while driving? It may be a sign that the glass face has come loose.

If the image in one of the external mirrors seemed to wobble when driving due to car vibration, the glass face may be partially detached from its backing. If this is the case, one can gently pull on the glass by the edge with a fingernail to pry it free from the housing, and remount it before it is lost. If you can see that the adhesive backing has partially released but the glass still seems stuck, applying a little heat from a hairdryer to the glass may help release the remaining backing. 

If it seems you are applying more than just a little force, the source of the wobble may be elsewhere in the mirror mount or its adjusting gimbal, and is not addressed in this document.

The original part is a high-quality glass mirror and is a very expensive dealer part, $200+. The aftermarket replacements are made of plastic and are not of the same quality, so I feel it is worth the effort to reuse the original glass part. In most cases, the root cause of the glass coming loose is that the sealing paint on the back of the mirror glass has failed, causing the glass to detach from its adhesive backing sheet. Here is how to fix it:

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• Separate the glass from the mirror housing.
• Clean the back of the glass with CRC QD Electronic spray cleaner or a similar product.
• If a small amount of the old adhesive backing remains on the glass, don't attempt to remove it, as doing so could damage the mirroring.
• Spray the back of the mirror glass with epoxy or urethane spray paint. If desired, using a darker paint color will make the lettering on the passenger-side mirror more visible.
•  I avoided using acrylic paint as it can be prone to adhesion issues. 
• I purchased the spray paint at a home improvement/hardware store to reseal it and let it dry overnight.
• Peel off the mirror's remaining adhesive backing sheet from the aluminum backing plate in the housing. For me, the adhesive sheet peeled off easily in one piece. 
• Leaving the car out in the sun to warm it up can help in softening the adhesive or; 
• Using a hair dryer to warm it up may help if you find the backing sheet stubborn to remove.
  
  
• Clean the aluminum backing plate of old adhesive with CRC QD Spray Electronic Cleaner or a similar product. First, wet the backing plate with the cleaner, then saturate a cotton rag and rub it onto the plate to remove the residual adhesive. The electronic cleaner will not attack the plastic parts.
  It may take several applications to soften the adhesive and remove it. Don't worry about it being pristine. If most of the adhesive is removed is all that is required.
• Apply the wider variety of 3M Super Strength Molding Tape (double-sided) or similar in strips to cover the back of the mirror, leaving the double-sided tape's second side red protection strips in place.

Mirror Aluminum Backing Plate

• Use scissors to trim the tape around the mirror so the tape strips do not extend past the edge of the glass.
• Peel the red second side strips from the tape, exposing the adhesive backing. Then;
• Gently press the glass into position onto the aluminum mount in the mirror housing for a perfect repair.
• The adhesive on the 3M tape is very strong so make sure the glass is oriented properly before the adhesive touches the backing plate.
• Take a look at the other mirror for reference, and consider making some cardboard shims and taping them in place along the inside edges of the mirror housing opening. This may help ensure a relatively even gap around the glass when pressing it into place.
• I positioned the bottom edge of the glass and then tilted it vertically until it came into full contact with the backing plate. An alternative is to apply adhesive tape to the aluminum backing plate, then align the glass.
• Once the tape comes in contact with the backing plate, it really can't be repositioned. 

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