Our A6 Avant starts making noise from the rear brakes, the rotors were shot, there weren’t any pad wear indicator. This is how we replaced ours.
The rear brakes are identical on both sides, so this is the passenger side pictures only. Before doing anything, make sure the car jacked up correctly, the other side has blocks to stop the car from moving forward/backward from jacking up the car.
Use 13mm & 15mm open wrenches to remove the brake bracket bolts (2)
Remove by lifting both the bracket and brake pads. If we’re going to just replace the pads, we can loosen the top bolt and remove the bottom bolt and lift the bracket upward to remove the pads only. But we’re going to replace the rotor, we need to remove both caliper and brake bracket. The brake bracket has 2-8mm hex bolts.
After 2 hex bolts removed, lift the brake bracket out and replace the new rotor, very simple procedure. Put some lock tight on the bolts before screwing them back in.
Put back the bracket, use a lug bolt to hold the new rotor in place. The next step is to compress the extended piston, we need to use the tool to turn and compress at the same time. The rear pistons always have to be done this way on most cars.
When the piston is retracted to the original position, place the new brake pads on the new rotor, put back the caliper, top bolt first, then drop it down over the springs of the pads slowly and carefully, then put back the bottom bolt. Tighten every bolts and we’re done. Give some lock-tight on the bolts.
Now, we don’t bleed the system, but we may have to suck some brake fluid out of the brake fluid reservoir because the piston compression. Check the reservoir level while compressing the piston, if it rises above the top, remove some using meat juice sucker or something to suck it out. We don’t open the piston bleed valve because the system is air-tight and working well.