When I got the mirror angled correctly, I marked it, and drilled through the door into the base of the mirror with a bit the right size for a 1/8' squeeze pin. I drove the squeeze pin into the base of the mirror. I enlarged the hole in the door so the squeeze pin would fit. Then tighten the mirror with the 1/4" bolt. The squeeze pin keeps the mirror in place without having to over tighten the 1/4 bolt.