Replacement of front pads on the S8 is an easy task, even if you've never done it before. Consider replacing the rotors if they have 50,000 miles or more on them. This will prevent you from having to do the job again anytime soon. Plus, you don't have to get the rotors turned, which can be a real hassle if it is not done correctly or you don't have two vehicles.
If the front brake pads are worn down, the rears are probably not far behind. Check them while doing the fronts. The rears DO NOT have wear sensors. When the brake pad backing plate comes in contact with the rotor and metal to metal contact is heard, you will know it's time to do the rears!
The following procedure shows the S8 Brembo four piston design.
Special Tools Required
No special tools are required
Brake cleaner and rags
The following picture is from the Bently manual. They identify the major brake components.
Take lug nut caps off and loosen lug nuts. Jack the car up and put front end up on jack stands. Raising the entire front end makes the job much simpler and safer. Remove wheel. Secure brake disc by reinstalling a wheel bolt.
After removing the wheel, secure the
brake disc by reinstalling a wheel bolt.
S8 Brembo front caliper with pads installed.
Disconnect brake pad wear sensor wire connector. Disengage connector from bracket using a screwdriver and simultaneously turn connector 90 degrees. Lift connector up and out and disengage wire.
Pull the two small circlips (Figure 1, Item 6) and retaining pins (Figure 1, Item 5) which hold down the pad retaining spring. Remove pad retaining spring.
Remove the old pads.
Push the pistons back. If you don't mind brake dust, they'll go back
with finger pressure; and make sure you don't overflow the brake fluid
reservoir. An alternate method is to place a screwdriver between the rotor and pad surface before removing the pad. Push the pistons back into the caliper by prying the screwdriver between the rotor and the pad surface.
Pushing the pistons back into the caliper by prying a screwdriver between the brake rotor and pad face. Ensure the brake fluid reservoir does not overflow.
S8 Brembo front caliper with pads removed
and pistons pushed all the way into the caliper.
Clean the brake calipers with brake cleaner and rags.
Insert the new pads. Note the the inner pad has the wire from the
pad wear sensor.
Install retaining spring, pins, and clips.
If you bleed the brakes, note that this caliper has two bleed screws. They must both be bled, the outer first.
S8 Brembo caliper bleed screws on left and right side.
When bleeding, bleed both, outer first.
Connect wear sensor wiring connectors.
Sit in the car and slowly depress the brake pedal until it firms up. This is pushing the pistons back out to its required position. Repeat other side. When complete, test drive your car around the block slowly. Take it easy on the brakes for the first couple of days or per manufacturer's instructions.