Brake pads are riveted with what we call a hollow shank rivet. It takes a rivet set that curls the hollow shank. Give these guys a call. http://www.rivetsinstock.com/rivets/brake-clutch-rivets.html

This is what the rivet set for hollow shank rivets looks like. http://www.rivetsinstock.com/rivet-tools/solid-semitubular-rivet-tools.html

I use one with a .401 Parker shank that fits in a pneumatic rivet gun. An air chisel will not work because it is not controllable enough. I have seen these type of rivet sets rigged up to work in an arbor press.