RE: [DML] Re: 3M VHB Tape on Rear-View Mirror?

["Tom Tait" <TTait@xxxxxxxxxx>]

I did glue my button on before I mounted the plex to the windshield, I
probably clamped it or used books too as you said, but I don't recall.
That write up was written while it was all still fresh in my mind.
 
I did use super glue too, as I recall on the first try the button did
come off the plex before I even mounted it.
 
The plex I used was likely thicker than what you found, 
 
I just emailed Randal the 3M guy to confirm the procedure for safely
removing the tape, and to see if black is available.  I'll let you know
what I learn.  If your button falls off the base again it may be worth
taking it off the windshield and clamping it.
 
More info soon!
 
Tom

________________________________

From: dmcnews@xxxxxxxxxxxxxxx [mailto:dmcnews@xxxxxxxxxxxxxxx] On Behalf
Of Joe Angell
Sent: Friday, July 27, 2007 11:15 AM
To: dmcnews@xxxxxxxxxxxxxxx
Subject: Re: [DML] Re: 3M VHB Tape on Rear-View Mirror?




I just did this recently myself with a compass/temp/map light/auto- 
dimming mirror due to a windshield replacement, using ideas that I 
found after reading posts the posts here (it sounds like they were 
your ideas, actually :) ). Previously, it had been carefully glued 
on at a vendor with my permission, and it worked, but I wasn't 
willing to try that again by myself.

I used a thin strip of clear plexiglass and moulding tape (which I 
believe is basically VHB). I cut a strip of plexi with a utility 
knife, and then just rounded the corners and beveled the edges a 
little with sand paper. I didn't do any bending of the strip or 
anything like that; I didn't notice much curve in the windshield at 
all, but maybe I used thinner plexi that could more easily match the 
contours of the glass. I also made the strip longer so that it 
stretched a couple inches below the black square on the windshield, 
which let me mount the larger mirror so that it wouldn't hit the 
headliner. My piece of plexi goes from an inch or two below the 
black square all the way up to very top of the windshield behind the 
headliner.

The tape holds the plexiglass onto the windshield very well. I don't 
think I'm ever getting it off again. The tape is grey, but it 
doesn't look too out of place to me.

I tried four times to use mirror adhesive to glue the mirror button 
on, but each time it fell off. I scratched the glue off the button 
and roughed up both surfaces with sandpaper each time I tried. I 
almost just ran a screw through the button. I finally just used a 
five minute epoxy, plus I braced a piece of wood wedge between the 
shifter and the button to provide constant force while the epoxy 
cured. In retrospect, I should have glued the button on before I 
taped the plexi to the windshield so I could let gravity and some 
books keep constant pressure on the button, but this seemed to work 
fine.

It's been a few days now and it hasn't fallen off, so I think I'm 
good. :)

Also, there was something else I toyed with, but didn't actually 
try. Since the issue is the thermal expansion difference between the 
metal button and the glass, I was wondering if you could cut a small 
piece of plastic that was the shape of the button, glue that to the 
window, and glue the button to that. The reason you can't just use 
tape that is the size of the button is due to the low surface area, 
and you can't use glue because of the metal expansion, but it seems 
like a glass-glue-plastic-glue-metal sandwich might be sufficient to 
dampen the effects of the expanding metal by the time it gets to the 
windshield. It seems unlikely to me that we need to worry about the 
glue itself expanding at a different rate. If this theory is 
correct, then this would result in a nearly factory appearance to the 
mirror install. I didn't feel like cracking the windshield I just 
replaced if I was wrong, though.

Now back to figuring out how to get those center console A/C vents 
back on that rubber cowling...

-- Joe

> Been there. Its quite a task. You can't use the adhesive or you will
> bust your windshield, and the standard mounting tapes from the vendors
> are too weak for the job. Its hard to find something that won't 
> damage
> the car, doesn't allow the Mirror to vibrate, won't drop of when you
> take a turn or park the sun for the day in the summer sun, and looks
> good. The good news is, I've done it. I did this about 18 months ago
> and have had zero problems since.
>
> So to mount the mirror you first need to create a new intermediate
> baseplate out of plastic. I used smoke plex. Black Sintra will likely
> work even better. I cut a strip approx. 1.5" wide (same width as the
> base of the mirror) by 9.5" long - the distance from the top of the
> windshield to the bottom of the mirror base, when it is its final
> position.
>
> ...
>



 


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