10042 Seating New Brake Pads
In the same way piston rings and a newly bored cylinder wear to match the wall, your brake pads and rotors need to match each other before the full amount of friction is reached. If, through a microscope, you were to look at the cross section of a brake pad and a rotor you would notice that their surfaces aren’t as smooth as you might think. In fact hills and valleys exist at their surfaces which cause a bit of standing off at first. Until these parts are mated only the tops of the hills are making contact with each other. If you apply the brakes with heavy effort before they are seated in you run the risk of overheating the pads and causing glazing, a glassy smooth surface to the pad which reduces the friction.
Before installing new pads and rotors be sure to clean the rotors thoroughly and lube the contact and sliding point of the brake system. It’s not a bad idea to take some light to medium grit sandpaper to the surface of the brake rotors prior to install to help knock off and non-directionalize the finish. Take the time to seat the new pads and rotors - it really counts.