1. Loosen the lug nuts that hold the wheels to the Audi’s hub. You can use a socket and a ratchet or a lug wrench. Lift the car with a heavy-duty floor jack and lower it onto jack stands. You can support either the front or the rear of the car on jack stands or you can support the entire car. Audis are heavy vehicles, so make sure to use caution and also to use high-quality jack stands.
2. Finish taking the wheels off and set them aside where they won’t become damaged or scratched. Spray the brake caliper and rotor with brake cleaner and wipe everything down thoroughly with a clean, dry rag.
3. Loosen and remove the two caliper bolts located on the back of the caliper (facing the wheel well) on the top and bottom. Most Audis use a star-shaped bolt, so use the proper Torx bit and a socket. You may also need a breaker bar (an extension on the ratchet for extra torque) to remove the bolts.
4. Remove the caliper from the rotor by sliding it off. You may need to angle the caliper a little to get the piston to retract enough to allow the caliper to slide off the rotor. Support the caliper with a length of wire tied to a nearby suspension component so that the brake line is not damaged from the weight of the caliper while you work. Disconnect the wire for the brake-pad wear sensor.
5. Remove the old brake pads from the rotor or from the caliper. Depending on the model of Audi that you have, the pads may stay with the rotor or they may still be in the brake caliper. Open the lid to the brake-fluid reservoir, located in the engine bay. Use a syringe or a baster to remove a small portion of the brake fluid so that it does not overflow when the caliper pistons are retracted to make way for the new pads.
6. Retract the caliper piston into the caliper by wedging a piece of wood (or the handle of a hammer) between the piston and the opposite side of the caliper and pressing on the piston. Install the brake pads in the opposite of removal. Reconnect the brake-pad wear sensor wire if your Audi has one.
7. Retract the rear caliper piston on newer Audis by using a special caliper-piston tool that fits into the piston and turns it while pressing it into the caliper.
8. Reinstall the caliper and the new pads by sliding the caliper over the rotor. Install and tighten the caliper-retaining bolts with the socket and ratchet. Repeat for the remaining corners of the vehicle. Replace the wheels and lower the car to the ground. Fill the brake-fluid reservoir with brake fluid. Pump the brake pedal until the brakes feel firm again.