Side mirror glass won't stay on...

[atownusa]

Hey all,

I've got an '89 911 and the mirror keeps coming off. It ends up hanging by the electrical wires. I know there's a hole on the bottom side of the housing that allows for a screwdriver to then turn the disc to snap the mirror into place, but I can't get it working.

Any tricks/tips out there for a newb?

Thanks!

[EC900]

There’s plenty of info to search here on PP also on the Yu Tube on flag mirrors.
If these are flag mirror, I think the pivot joint may have come loose and you’ll need to remove and disassemble to tighten this up. Likely the nut has worked its way loose. This pivot adds the tension to keep mirrors attached to the base also keeps mirror in place and allows them to be folded. This pivot screw post can be a tough project due to the spring tension and tightening with a spline driver or large flat head screwdriver, but you’ll find that wires will be in the way.
Take a look at the PET that show the anatomy…



Also, here’s a good tutorial on flag style mirror removal…

https://youtu.be/QYpBfatozWw

[EC900]

Edit -
I may have misunderstood…you say the mirror glass is hanging or the entire mirror module ?
The retaining ring to hold just the mirror glass is accessed by tilting the mirror in such a manner to slide a thin screwdriver underneath to lock it to the bracket.
More on that here;
Flag Mirror Help