Brake System: Other Audi A6 C5 facelift

BLEEDING PROCEDURES

Note. Brake fluid should be replaced every 2 years regardless of elapsed mileage.

Electronic Stability Program (With ESP 5.3)

Note. Electronic Stability hydraulic unit must be bleed using VAG 1551 or VAG 1552 scan tool.

Note. A positive pressure of 29 psi must be maintained to bleed hydraulic pump. Before beginning bleeding procedure, verify pressure bleeder setting.

1. Connect pressure bleeder US1116 or equivalent, to master cylinder reservoir. Connect hose to brake caliper bleed screw and insert other end of hose in a clear container 1/4 full of clean brake fluid. Bleed air from brake system in following order: Right Front Left Front Right Rear Left Rear
2. Turn ignition off. Connect scan tool to Data Link Connector (DLC). DLC is located under dash to left of steering wheel. (Scheme 35) Bleeding of hydraulic unit is accomplished with scan tool in diagnostic function 04 - BASIC SETTINGS mode of address word 03 - BRAKE ELECTRONICS. Following scan tool instructions, navigate to BASIC SETTINGS mode. Connect hose to left front caliper bleeder screw, and insert other end of hose in a clear container 1/4 full of clean brake fluid.
3. Using scan tool command hydraulic pump on. Pump should run for 10 seconds. Repeat procedure until brake fluid runs clear with no air bubbles.

Scheme 35

Electronic Stability Program (With ESP 5.7)

Unlike ESP 5.3, ESP 5.7 does not incorporate hydraulic pump for traction control. Therefor it is not necessary to bleed the brake system with the diagnostic tester. When pressure bleeding brake system, a pressure of at least 29 psi (2 bar) is required for bleeding the hydraulic unit. Always check the pressure setting on the bleeding device. Bleed system as follows

1. Connect pressure bleeder US1116 or equivalent, to master cylinder reservoir. Connect hose to brake caliper bleed screw and insert other end of hose in a clear container 1/4 full of clean brake fluid. Bleed air from brake system in following order: Right Front Left Front Right Rear Left Rear
2. Continue bleeding at each wheel until brake fluid runs clear with no air bubbles.

Pedal Bracket With Internal Thread For Brake Light Switch

With brake pedal released, measure distance "A". (Scheme 36) If distance is not.004-.020" (.1-.5 mm), loosen lock nut and adjust as necessary.

Scheme 36

Pedal Bracket With Spring Clip For Brake Light Switch

The switch must installed only ONCE to ensure it is adequately tight. Insert switch into installed clip and press in to step. (Scheme 37) After adjustment, brake pedal must not be under preload. If necessary, turn switch back slightly, noting clearance

Scheme 37

Non-Spring-Type Clip Mounted Vent Valve

Insert vent valve in installed clip and press in until stop. Press back valve by pulling back the brake pedal until cable is contacted. In order to assure sufficiently secure fitting, valve must not be installed more than once.

Spring Clip Mounted Vent Valve

Procedure is same as that used to adjust brakelight switch. See BRAKELIGHT SWITCH .

POWER BOOSTER PUSH ROD

Note. Audi refers to power booster push rod as ball head adjustment.

Measure push rod length whenever power booster or master cylinder is replaced. Push rod length is measured from master cylinder mounting flange to end of ball head. When measuring, ball head must be at a right angle to surface of the brake booster. Measure to end of ball head without seal. Measure distance "A". (Scheme 38) Adjust push rod length if not as specified. See POWER BOOSTER PUSH ROD LENGTH table.

POWER BOOSTER PUSH ROD LENGTH

Scheme 38

PARKING BRAKE

Note. Adjust parking brake only if parking brake cable, rear brake pads or rear caliper have been replaced.

Scheme 39

Scheme 40

Scheme 41

Scheme 42

1. Press brake pedal firmly. Remove rear passenger compartment ashtray. Use flat-bladed tool to prevent compensator from turning. (Scheme 39) Remove plastic shielding and discard (if present).
2. Raise and support vehicle. On Front Wheel Drive (FWD) vehicles, locate parking brake adjustment nuts in the tunnel on the underside of the vehicle. On All Wheel Drive (AWD) vehicles, adjusting nuts are in front of rear lower control arms.
3. On all models, remove locking clip "D". (Scheme 40)Counter-holding hex "E", turn adjusting nut "C" until it stops. Slide cable adjuster "B" together. Turn adjusting nut until slot for locking clip is visible. Install locking clip "D".
4. Pull both cable sleeve adjusters apart simultaneously until cables are tensioned. Lever at rear brake caliper must not lift from stop. Remove screwdriver from compensator. Apply and release parking brake 3 times. Check parking brake adjustment. If necessary, fine tune adjustment by turning cable adjuster "B".
5. The colored "O" ring must not be visible. (Scheme 41) This ensures that the parking brake cable adjustment mechanism is sufficiently protected against dirt and water spray. Check parking brake tension and adjust fine adjustment in or out if necessary.
6. Check distance "A" at rear caliper. (Scheme 42) Lever should not contact brake caliper. Gap should be visible but no wider than 0.059" (1.5 mm).

BRAKE PAD WEAR INDICATOR

Brake pads that have reached the end of their service life are indicated on instrument cluster by the Brake Pad Wear Indicator. Indicator will go out when NEW brake pads with NEW brake pad wear sensors are installed on vehicle.

VACUUM CHECK VALVE

To check function of check valve, blow air through valve. Air must pass through in direction of arrow. Valve must remain closed in opposite direction. Ensure that check valve is installed correctly.

BRAKELIGHT SWITCH

Remove storage compartment on driver's side. Disconnect brakelight switch harness connector. Loosen lock nut, and remove switch by turning switch counterclockwise. Installation is reverse of removal. After installing switch, adjustment is necessary. See BRAKELIGHT SWITCH under ADJUSTMENTS. Verify proper functioning of brake lights.

ELECTRIC VACUUM PUMP

Remove engine cover. Disconnect electric vacuum pump harness connector. Vacuum pump is located below master cylinder. (Scheme 43) Remove vacuum hose. Unclip pump by hand, and pull up on vacuum pump. To install, reverse removal procedure.

Scheme 43

FRONT PADS

Note. If re-using brake pads, mark them so that they can be installed in their original positions to prevent uneven braking.

PARKING BRAKE HANDLE

Use following illustrations to aid in removing and replacing parking brake handle. (Scheme 45)

Scheme 44

CENTER CONSOLE

Removing and installing rear part of center console is necessary for access to parking brake handle. For removal and installation procedures (Scheme 46)- see scheme 41.

Scheme 45

Scheme 46

Scheme 47

Scheme 48

Scheme 49

Scheme 50

FRONT CALIPER (HP2, ALUMINUM CALIPER)

Scheme 51

Scheme 52

Scheme 53

Scheme 54

1. Insert brake pad (b) in piston. Place a wooden board (a) into the recess of the caliper housing to catch the pistons so they are not damaged. (Scheme 53) Use compressed air to remove pistons. Only one piston can be pressed out at a time. Hold the other piston securely in brake caliper housing using piston resetting tool.
2. Removing piston seals using Wedge (3409). When removing, make sure that surface of cylinder is not damaged. (Scheme 54)
3. Install piston dust seals on piston. Insert lip of piston dust seal using Wedge (3409). Hold piston in front of caliper housing for this procedure. (Scheme 55)
4. Insert piston in hole by hand. Insert brake pad (a) in piston before inserting in brake caliper housing. (Scheme 56) Outer sealing lip of protective cap will then engage in piston groove.

FRONT CALIPER (BREMBO)

Scheme 55

Scheme 56

Scheme 57

1. Remove pads, and clean exterior surfaces.
2. Use air pressure to force piston from cylinder. Only one piston can be pressed out at a time. Hold the opposite piston in position in the brake caliper housing using a piston resetting tool. Block the other pistons using wooden blocks. Place a wooden board in front of the piston resetting tool to prevent the piston from being damaged when being pressed out.
3. Remove piston dust seals using Wedge (3409). see scheme 53 When removing, make sure that surface of brake caliper is not damaged.
4. Remove piston seals using Wedge (3409). see scheme 54 When removing, make sure that surface of brake caliper is not damaged.

MASTER CYLINDER

Manufacturer recommends replacement of master cylinder if defective.

VACUUM POWER BOOSTER

Manufacturer recommends replacement of vacuum power booster if defective.