Removing side view mirror base

[davidrbroder62]

I am trying to replace the driver side sideview mirror of my 1996 Z3. The bolts are completely corroded and have no heads on them. I was told to drill them out. In attempting to do that I have destroyed several drill bits which have broken off in the attempt.
The base is not moving, I dont want to damage the door but am at a loss.
Anyone else try to attempt this? What did YOU do to accomplish this task?

 

[Jam03]

I can’t help, but am sympathetic. My bolt heads were not too badly corroded.

 

[IainP]

I am trying to replace the driver side sideview mirror of my 1996 Z3. The bolts are completely corroded and have no heads on them. I was told to drill them out. In attempting to do that I have destroyed several drill bits which have broken off in the attempt.
The base is not moving, I dont want to damage the door but am at a loss.
Anyone else try to attempt this? What did YOU do to accomplish this task?

Cobalt drill bits from Toolstation, 40442 is a set of six, but you’ll likely need an 8mm as well. Use a little lube and don’t use too high a speed, they’ll go through the head like butter.

 

[AntStark]

You could try getting a reverse (left handed) drill bit..as long as you have a drill that will also go in reverse. I promise it’s a thing..it’s not tartan paint or anything like that

 

[Duncodin]

Drilling the bolt head off will get the mirror base off but then you'll still have the bolt shaft/thread stuck in the door. Not sure how easy that will be to get out. I can't remember how the captive nut thread is attached to the door panel.

I think I'd have tried an extractor.

 

[Mazza]

worst case… you drill out the bolts and damage the thread in the door.
but then just drill out and insert a Rivnut… ( I have loads of different sizes if you need any. )