i have 2 brand new door shells and need to install my sport mirrors on my 69. there are no holes drilled yet. I need to know the best way to install the threaded inserts into place for the mirror to mount to. Do they get pressed in and welded or what?
They are sometimes called riv nuts. There is a special tool, which looks and operates just like a pop rivet gun.
They way it works is you first get the correct size riv nut. Im not talking about the screw size(although obviously that matters) I am talking about the diameter and grip length. If the grip length is wrong, the riv nut will not be correctly compressed and may not hold in place.
Drill your holes, screw the rivnut onto the stud on the tool, insert it into the holes in the door, and squeze the handle, just like a pop rivet tool. The unthreaded portion of the rivut will squish and clamp down on the door. This is why the grip length must be correct for the thickness of material that it is being attatched too.
use the riv nuts but use the steel ones,not aluminum they will spin when you try to tighten the screws. if you are near a harbor freight they have one that works quite well for around $19..00 with several screw sizes. it has the size you will need. you can find the steel riv nuts at Ace hardware. also use stainless screws they wont rust.