When I purchased new "Wilwood" brakes there were instructions for "Breaking In The Rotor" and "Breaking In The Pads".
Breaking In The Rotor: I would gently heat the rotor by driving at first slowly and bringing Morgan to a stop and then a bit faster and gently bring the Morgan to a stop etc. until the rotors were quite hot and then let them cool down until I could touch them with my fingers.
Breaking In the Pads: Same as "Breaking In the Rotor" but a more aggressive stop until I could smell the Brake Pads.
I think this procedure was to prevent warping the rotors. Not totally sure what Breaking In The Pads did, but the braking certainly improved.
