Does anyone know whats under the black button in the center of this pic? I'm looking for a place to mount a Go Pro camera.
Agreed, that's how I remember it, no metal bolt inserted, it was all plastic. I thought it was poured in hot plastic. I may have inserted a hot screwdriver to remove it. I still have a ~2" tall aluminum pedistal with a ball on the end that fits a Garmin GPS installed in the mirror hole. Ended up liking the GPS in the center, so I use the 2" tall aluminum pedistal with a ball to hang my helmet.I didn't save the stuff I took out of the hole, but I don't recall a metal bolt under the plastic cap. It was plastic all the way down. My guess was, they put the plastic in the hole while it was still soft, and let it harden in place, because the cap was not designed to be removed.
Also the threaded hole is a 10mm X 1.25, somewhat less common than the easy-to-find 10mm x1.00 thread size.