Setting up brakes on bicycles can sometimes be an exercise in utter frustration. Several factors contribute to setup issues. People will reuse poorly worn pads, use bent rotors, over fill resoviors and just mismatch parts.
One issue most overlooked is the geometry of the caliper mount. Some people do take the time to machine the frame/fork interface so that the post mount surface is parallel to the wheel axis. That’s a major step in setup. It goes further though. The adapter and caliper surface themselves need to be checked and probably worked. At the very least, paint and build-up need to be removed for good mating.
It’s dramatic what a difference this can make. Setting up brakes becomes far easier and a much smoother process. Parts lock into position with precision.
I’m looking into making a fixture for milling the caliper face so that it is perpendicular to the piston faces. It’s a little tricky to do while the caliper retains fluid. Hopefully in the next few months. Regardless, even making the attmpt to clean up the surface with a file makes a massive difference.
Also, remember to always use threadlocker on brake hardware!