Mirror Mount torn out of door; how do I fix

[SunRader78]

1978 620: Noticed the passenger side mirror was shaking pretty bad at highway speeds,

Went to check and it was quite loose, removed the mirror to reveal the problem:

The sheet metal in the door had begun to crack outwards weakening the mirror mount.

What are my options here to fix it the right way?

 

Driver's side for reference:

[MikeRL411]

FIRST!  Get the smallest drill bit you have.  Drill a stop crack hole just in front of the existing cracks.  Now worry about how you are going to weld or braze the existing cracks.  Silver soldering a plate over the existing area [yes inside the door] and re-drilling just might be a solution.

[Draker]

Gonna have to weld it.

 

Good idea regarding drilling hole to stop the crack.

[distributorguy]

Find a washer that's a bit bigger than the hole in the door.  

Find a bolt that fits through the mirror mount and through that washer.  

Weld a nut to the back side of that washer (do all this twice).

Weld the washer to the inside of the door panel.  The washer will prevent the door from contining to crack, and the bolts won't rely on the sheet metal's strength to hold the mirror in place.  

 

Or just bolt it all together, skip the welding, and drill the hole mentioned above for the quickest repair if you don't weld.  

[kelowg]

Metal fatigue is killing our sheet metal. So even welding up cracks is only temp fix. But being an rv u dont have many mirror opts. Welding heavier gauge metal to back side of mounting points would help to prevent vibrations and stiffen up the panel. 

[SunRader78]

Excellent advice - Thank you.

I'll let you know how it works out.

[DaBlist]

If you want to save the paint make a plate to reinforce from behind as mentioned and install with panel bonding adhesive