First hot day, mirror falls off

Last year I bought a couple of used cars, and when it got hot the rear
view mirrors fell off both of 'em. So I glued them back on with the
glue kits they sell for that purpose. I followed the directions,
cleaned carefully and let the glue harden over night.

It got pretty hot this week, and they both fell off again a few days
apart.

So I'm wondering if the windshield shades I use in both cars are the
problem. I use the kind with fabric and wire frames that twist and
fold up into a very small space. They push a little against the
mirror, and while they keep the interior of the car cool, I think the
windshield gets pretty hot, maybe hotter than without them.

Any suggestions on this? I'm particularly interested if you live
somewhere hot like Arizona. What's your experience?
-Paul

 

I'd trim away the windshield shades around the mirror-mount to reduce
pressure against the mirror. I also have had better success with a
good superglue or 2-part epoxy than the glue kits sold to re-attach
mirrors.

Suggest you also tape the mirror mount on after glueing, to put put
pressure on it against the glass while the adhesive cures.

 

The kits I tried used superglue (at least, it looked the same and
smelled the same). I was re-installing the mirror annually for a
while; JB-Weld (a two-part epoxy sold at auto parts stores) fixed it
permanently (so far; it's been over a decade).

Definitely.

 

Thanks for the tips. The "official" rear view mirror adhesive seems to
be flexible. My kit came with a razorblade to remove the old stuff, and
it's like a patch of clear plastic- bends, stretches, comes off in one
piece. Maybe they figure it's better to have it come off once a year
rather than risk damaging the windshield. Flexibility probably helps
with the differential thermal expansion between the glass and the metal
piece too.

I bought a kit to replace the first mirror when it fell off, and so I
used that to glue both of 'em on this time. If they come off again,
I'll try the 2 part epoxy. I use that all the time to repair other
things.
-Paul

 

Your kit is substantially different from the kits I got (at least one
from Mopar, at least one from NAPA, don't really remember how many
from each source) -- mine had an ampule of what I took to bes uperglue
and other accessories. So your mileage will most assuredly vary on
how well the kit works.

 

I don't remember what brand the other kits I used were, but this one
was a Permatex kit.
It came with a razor blade for removing the old glue, a strip of
sandpaper for polishing the metal mirror mount, a wipe with
sealer/accellerant, an ampule with the adhesive, and an alcohol wipe
for cleaning the felt tip marker ink off the windshield.

I only remember the accellerant and adhesive being in the other kits.

One other thing- seems like it always leaves the adhesive on the
windshield, so it doesn't stick as well to the metal...
-Paul

 

The secret with these kits to make a good bond is to use an extremely SMALL
amount of the glue, and the second you put the half-drop on that is required
you
immediately smack it squarely against the winshield, hold it against the
winshield
with as much pressure as you dare, and DO NOT MOVE IT until the glue hardens
in a couple minutes. Most people that don't do these regularly use way too
much glue, not enough pressure, and move the damn thing around getting it
positioned
after putting it against the window. And you also have to have a perfectly
clean
surface on each side, and the kit needs to be pretty new.

Superglue is one of my least favorite adhesives. It has practically zero
shelf life
after manufacture, no shelf life whatsoever after opening, won't glue most
plastics
worth a damn, won't glue anything porus worth a damn, sets up almost
immediately,
and can't stand shear shocks. About the only things it's good for are
gluing
skin together.

The two part, long setup epoxies are the best. JB Weld is the most well
known,
but any industrial supply house sells long-setting epoxy that has the same
24 hour setup
time that JB Weld has, and holds with the same ability. They also have a
huge
shelf life. I remember getting a baby jar full of epoxy and a baby jar full
of hardener from
by Dad's workplace from the taps on the 55 gallon barrels of industrial
epoxy, and
I used those for at least 10 years before the hardener finally ended up
solidifying.

Ted