Before you work, use the jackstand to lift the car and keep it supported on the jackstands. Hold the brake caliper, leave the brake hose connected, then lift it off and secure the caliper in place with a length of wire. Look at both sides of the rotor for deep score marks; light damage and small grooves are fine, but deep scoring means you need new rotors and resurfacing. Look at both sides of the brake disc-if the vehicle knbuces when you apply the brakes, the disc might not be round. An automotive machine shop should resurface the disc if you find runout when you reattach the cap nuts (in the opposite direction) and measure the difference from the disc's edge with a dial gauge-as long as it's less than the allowed amount. Make sure the machine shop doesn't grind the disc too thin but leaves the minimum thickness cast or stamped onto the disc, which you can measure with a micrometer. First exit the caliper for CTS-V models, next reverse the lug nuts, then unscrew and pull off the screw on the hub-attached plate to extract the disc total. Before putting the disc in place, scrape off dirt and rust from the hub surface and clean the entire hub-facing side of the disc center with wire brush. Put a little bit of high-temperature anti-seize on both the wheel hub's edge and the raised area next to it. Put the disc over the stud, put the bolt through its hole, and turn it to the recommended tightness. Mount the caliper and its bracket, and fasten the bolts according to the recommended torque forces. Put the wheel on, let the car hit the ground, and properly tighten the wheel lugs until they meet the prescribed torque rating. Pull down on the brake three times to let the brake pad touch the disc, then double-check the brakes work correctly before you can drive.