2009 Chevrolet Silverado 3500 HD Brake Disc

You should remove the Brake Caliper, drain all the brake fluid from the caliper, secure the brake caliper in a suitable holding device, insert a piece of wood in the brake caliper between the pistons and the outer bridge, cover the brake caliper with a shop towel, apply filtered, non-lubricated compressed air into the brake hose inlet fitting port of the brake caliper, remove the pistons, remove the boots, remove the piston seals, remove the bleeder valve cap, remove the bleeder valve, clean the bleeder valve, the caliper bores, the caliper passages and the pistons with denatured alcohol, clean the brake caliper assembly with denatured alcohol and then dry with filtered, non-lubricated compressed air.

You should discard the brake pad shims, clean the brake pad hardware mating surfaces of the caliper bracket of any debris and corrosion, apply the brake pedal to approximately 2/3 of its travel distance, release the brake pedal, fill the master cylinder to the proper level and then burnish the brake pads and rotors.