Brake System Audi A6 C5

MODEL IDENTIFICATION

MODEL IDENTIFICATION

A6, Allroad, RS6 and S6 models are equipped with one of several brake systems. Brake caliper application is designated by the Production Code (Pr. No.). Pr. No. is printed on vehicle data sticker located in spare tire well or in owners customer's service schedule. (Scheme 1) For brake caliper Pr. Nos., see PRODUCTION CODES table. To identify brake system and components (Scheme 2)- (Scheme 7).

PRODUCTION CODES

Scheme 1

Scheme 2

Scheme 3

Scheme 4

Scheme 5

Scheme 6

Scheme 7

DESCRIPTION & OPERATION

All models have self-adjusting front and rear disc brakes. The cable actuated parking brake mechanically activates the rear calipers.

Hydraulic system uses a tandem master cylinder with vacuum assist. Hydraulic system is diagonally split. Left front and right rear wheels form one circuit. Right front and left rear wheels form the other circuit. The brake pressure regulator has been deleted, as regulation function has been replaced by ABS control module programming.

Turbocharged models are equipped with an auxiliary electric vacuum pump. Vacuum pump supplies vacuum to power booster ensuring adequate vacuum for proper vacuum assist. Vacuum pump is activated by vacuum sensor signal to ABS control module. Vacuum sensor is located in power booster vacuum line.

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 8) 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 8

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 9) If distance is not.004-.020" (.1-.5 mm), loosen lock nut and adjust as necessary.

Scheme 9

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 10) After adjustment, brake pedal must not be under preload. If necessary, turn switch back slightly, noting clearance

Scheme 10

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 11) Adjust push rod length if not as specified. See POWER BOOSTER PUSH ROD LENGTH table.

POWER BOOSTER PUSH ROD LENGTH

Scheme 11

PARKING BRAKE

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

Scheme 12

Scheme 13

Scheme 14

Scheme 15

1. Press brake pedal firmly. Remove rear passenger compartment ashtray. Use flat-bladed tool to prevent compensator from turning. (Scheme 12) 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 13)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 14) 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 15) 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.

Description & Function

The electric vacuum pump is only installed in vehicles with automatic transmission. It is switched on by Engine Control Module (ECM) depending on intake manifold pressure. Vacuum pump is On Board Diagnostic (OBD) capable. Detected malfunctions are stored in Engine Control Module (ECM) memory. See appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE. Testing function of electric vacuum pump via On Board Diagnostic (OBD) must only be performed with engine at standstill.

Testing

1. Electric vacuum pump is tested using VAS 5051 or VAG 1551 scan tool in diagnostic function 04 - BASIC SETTING mode. Before beginning procedure ensure that battery voltage is 11 volts or more, engine and transmission grounds are okay, engine is not running and transmission is in Neutral or Park.
2. Turn ignition off. Connect scan tool to Data Link Connector (DLC). DLC is located under dash to left of steering wheel. (Scheme 8) Turn ignition on. Following scan tool instructions, navigate to BASIC SETTINGS mode.
3. On scan tool, press keys "0", "0" and "8" to select "PERFORM SHORT TRIP UP 28" function. Press "Q" key to confirm entry. Press "4" key. Firmly apply brake pedal several times to vent power booster.
4. When power booster is vented electric vacuum pump should begin to run. Once test has begun DO NOT press brake pedal until testing is complete. Diagnosis of electric vacuum pump is run in parallel in the control module. System passes test if power booster reaches shut-off threshold within specified time (about 20 seconds).
5. If electric vacuum pump does not run during test, check circuits between vacuum pump and ABS control module. See ANTI-LOCK BRAKE SYSTEM wiring diagram in appropriate SYSTEM WIRING DIAGRAMS article in ELECTRICAL. If no problem with wiring is found, replace vacuum pump. See «ELECTRIC VACUUM PUMP»(/audi/a6/c5-1997-2001/remont/mechanical-hydraulic/#brake-system) under REMOVAL & INSTALLATION. If vacuum pump continues to run on, go to next step.
6. Check for leaks in power booster, vacuum line or vacuum pressure sensor. If problem is found, repair as necessary. After repair, repeat steps 1 - 4.
7. To verify repairs, on scan tool press "0" and "3" to select "FINAL CONTROL DIAGNOSIS" function. Press "Q" key to confirm entry. Press arrow key until, FINAL CONTROL DIAGNOSIS is displayed. Vacuum pump should run for about 10 seconds.

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 16) Remove vacuum hose. Unclip pump by hand, and pull up on vacuum pump. To install, reverse removal procedure.

Scheme 16

Removal & Installation

1. Raise and support vehicle. Remove wheels. If replacing calipers, disconnect brakeline from caliper, and plug openings. If not replacing calipers, DO NOT disconnect brake line from caliper. Hang brake caliper from body or suspension. Do not allow caliper to hang by brake hose or line.
2. On all calipers, remove caliper mounting bolts. (Scheme 2)- (Scheme 3). Remove caliper assembly from wheel bearing housing.
3. To install, reverse removal procedure. Tighten fasteners to specification. See «TORQUE SPECIFICATIONS»(/audi/a6/c5-1997-2001/remont/mechanical-hydraulic/#brake-system__torque-specifications). Bleed hydraulic brake system. See «BLEEDING BRAKE SYSTEM»(/audi/a6/c5-1997-2001/remont/mechanical-hydraulic/#brake-system) under BLEEDING BRAKE SYSTEM.

FRONT PADS

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

Removal & Installation (FN3)

1. Raise and support vehicle. Remove front wheels. Secure brake disc with a wheel bolt.
2. Remove protective caps. (Scheme 2) Using a flatbladed tool, pry off brake pad retaining spring from brake caliper housing and remove.
3. Remove both guide pins from brake caliper. Remove brake caliper housing and support so that the weight of the brake caliper does not burden or damage the brake hose. Remove brake pads from brake caliper housing or from brake carrier.
4. To install brake pads, press piston back into caliper housing using resetting tool before inserting new brake pads. Before pushing back the piston, draw off brake fluid out of the brake fluid reservoir with a bleeder bottle. Otherwise, especially if reservoir has been topped off, fluid will overflow and cause damage.
5. Insert brake pad with retaining spring in brake caliper housing. Inner pad (with spring) is marked with an arrow. The arrow must point in the direction of forward rotation of the brake disc when installed. Noise may result from incorrect installation.
6. Remove protective foil on backing plate of outer brake pad. Install outer brake pad on brake carrier. Install brake caliper housing in brake carrier using both guide pins, and tighten to specification. See «TORQUE SPECIFICATIONS»(/audi/a6/c5-1997-2001/remont/mechanical-hydraulic/#brake-system__torque-specifications).
7. Install both protective caps. Install retaining spring in brake caliper housing. Retaining spring must be pressed under brake carrier after it is inserted in both holes. If the spring is improperly installed, the brake caliper cannot adjust to compensate for wear on the outer brake pad. This will cause the brake pedal travel to increase.
8. Install wheels and tighten to specification. See «TORQUE SPECIFICATIONS»(/audi/a6/c5-1997-2001/remont/mechanical-hydraulic/#brake-system__torque-specifications). After installing brake pads and before moving vehicle, depress brake pedal several times firmly to properly seat brake pads in their normal operating position. Check brake fluid level, and top off as necessary.

Removal & Installation (FNR-G60)

1. Raise and support vehicle. Remove front wheels. Secure brake disc with a wheel bolt.
2. Using screwdriver, pry off brake pad retaining spring from brake caliper housing and remove. (Scheme 3) Disconnect brake wear indicator harness connector. Using a flatbladed tool, release harness connector from the holder turning connector by 90 degrees at the same time. Pull connector out upward and unhook the wire.
3. Detach brake line from bracket. Remove trim cap and unscrew both guide pins and remove from brake caliper. Remove brake caliper housing and lay to one side so that the weight of the brake caliper does not stress or damage the brake hose. Remove brake pads from brake caliper housing or from brake carrier.
4. To install pads, press piston back into caliper housing using resetting tool. Before pushing back the piston, draw off brake fluid out of the brake fluid reservoir with a bleeder bottle. Otherwise, if reservoir has been topped off, fluid will overflow and cause damage to finish.
5. Insert brake pad with retaining spring and wear indicator into brake caliper housing. Install outer brake pad onto brake caliper. Insert pads in brake carrier and install together on brake caliper and brake disc. Secure brake carrier to brake caliper housing with both guide pins, and tighten to specification. See «TORQUE SPECIFICATIONS»(/audi/a6/c5-1997-2001/remont/mechanical-hydraulic/#brake-system__torque-specifications).
6. Ensure brake hose is installed without twisting. Install both protective caps. Insert retaining spring into brake caliper housing. Retaining spring must be pressed under brake carrier after it is inserted in both holes. If the spring is improperly installed, the brake caliper cannot adjust to compensate for wear on the outer brake pad. This will cause the brake pedal travel to increase. Attach brake line. Connect harness connector for wear indicator and engage line in dust cap and trim cap.
7. Install wheels and tighten to specification. See «TORQUE SPECIFICATIONS»(/audi/a6/c5-1997-2001/remont/mechanical-hydraulic/#brake-system__torque-specifications).
8. After installing brake pads and before moving vehicle, depress brake pedal several times firmly to properly seat brake pads in their normal operating position. Check brake fluid level, and top off as necessary.

Scheme 17

Scheme 18

Scheme 19

Scheme 20

1. Raise and support vehicle. Remove wheels. Install one wheel bolt to secure brake disc.
2. Disconnect connector for brake pad wear indicator. (Scheme 17) Disengage connector from bracket using a screwdriver and simultaneously turn connector 90 degrees. Lift connector up and out and disengage wire.
3. Press upper and lower spring tensioner out of locking mechanism using pliers. Slide spring to side. (Scheme 18)
4. Press piston back into brake caliper housing. To do this, insert floating frame using a screwdriver and press powerfully outward.
5. Use screwdriver to press outer brake pads off brake caliper. (Scheme 19)
6. Press floating frame in direction of arrow until stop. (Scheme 20) Carefully press brake pads out of piston and remove brake caliper housing.

Scheme 21

1. Clean brake caliper housing thoroughly before installing new brake pads. Be especially careful to remove any residual adhesive foil, left by outer brake pads.
2. Insert lower and upper brake pads in piston. Be sure protrusions on backing plates are securely installed in brake piston. Do not damage protective caps when installing brake pads. (Scheme 21)
3. Press floating frame caliper outward until it contacts stop. (Scheme 22)
4. Install upper and lower tension (anti-rattle) springs in correct position. (Scheme 4)and (Scheme 18).
5. Remove wheel bolt from wheel hub. When installing wheels, ensure rim flange does not rest on brake caliper. This could push pads out of position.
6. After installing brake pads and before moving vehicle, depress brake pedal several times firmly to properly seat brake pads in their normal operating position. Check brake fluid level, and top off as necessary.

Scheme 22

1. Raise and support vehicle. Remove wheels. Install one wheel bolt to secure brake disc.
2. For RS6, remove damper bracket bolts and remove bracket. On all models, disconnect connector for brake pad wear indicator. (Scheme 23) Disengage connector from bracket using a screwdriver and simultaneously turn connector 90 degrees. Remove lower half of connector out of holder.
3. Drive out pad retaining pins (arrows). Remove anti-rattle clips.
4. Press off the brake pads from the brake disc and remove pads from the brake caliper housing.
5. Press piston back. Insert brake pads into brake caliper housing. The brake pads are directional, note the markings on the damping panel. Install pad retaining springs. Press retaining springs downward and drive in pad retaining pins to stop.
6. To finish installation, reverse remaining removal procedure. On RS6, notch on damper bracket must face out. Damper bracket mounting points should make full contact with contour of bracket. Use thread locking fluid on damper bracket mounting bolts. Tighten nuts and bolts to specification. See «TORQUE SPECIFICATIONS»(/audi/a6/c5-1997-2001/remont/mechanical-hydraulic/#brake-system__torque-specifications).
7. After installing brake pads and before moving vehicle, depress brake pedal several times firmly to properly seat brake pads in their normal operating position. Check brake fluid level, and top off as necessary.

1. Raise and support vehicle. Remove wheels. Remove brake calipers. See «FRONT CALIPER»(/audi/a6/c5-1997-2001/remont/mechanical-hydraulic/#brake-system) . Slide rotor off hub.
2. To install, reverse removal procedure. Tighten fasteners to specification. See «TORQUE SPECIFICATIONS»(/audi/a6/c5-1997-2001/remont/mechanical-hydraulic/#brake-system__torque-specifications) . If hydraulic system was opened, bleed hydraulic brake system. See «BLEEDING PROCEDURES»(/audi/a6/c5-1997-2001/remont/mechanical-hydraulic/#brake-system__bleeding-procedures) under BLEEDING BRAKE SYSTEM.

Removal

1. To catch leaking brake fluid, place sufficient lint free cloths in area of plenum chamber, engine and transmission. Install bleeder hose and bleeder bottle to the front left brake caliper bleeder screw and open bleeder screw. Operate brake pedal until sufficient amount of brake fluid has been pumped out for the brake fluid level in the brake fluid reservoir to sink below the clutch master cylinder supply hose (if equipped). Close front left bleeder screw.
2. Disconnect and clamp clutch master cylinder supply hose (if equipped) and seal with a plug. Disconnect brake fluid level warning indicator sensor harness connector. Remove reservoir retaining bolt. Remove brake fluid reservoir. To do this press down the locking tab on the reservoir and at the same time pull the brake fluid reservoir out of the sealing plugs.
3. Disconnect brake lines on brake master cylinder and seal brake lines and threaded holes with plugs from repair kit Part No. 1H0 698 311 A. Remove brake master cylinder nuts. (Scheme 24) Carefully remove brake master cylinder from brake booster unit.

Scheme 23

Installation

To install, reverse removal procedure. Always use NEW "O" ring between master cylinder and brake booster. When installing the brake master cylinder and brake booster unit together, make sure that the push rod is correctly located in the brake master cylinder. Apply slight pressure to the brake pedal to move the push rod towards brake master cylinder; this makes it easier to guide brake master cylinder onto the push rod. Tighten fasteners to specification. See TORQUE SPECIFICATIONS . Bleed clutch and brake systems. See BLEEDING BRAKE SYSTEM .

Front-Wheel-Drive Vehicles

Use following illustrations to aid in removing and replacing parking brake cables on Front Wheel Drive (FWD) vehicles. (Scheme 25)- (Scheme 29).

Scheme 24

Scheme 25

Scheme 26

Scheme 27

Scheme 28

All-Wheel-Drive Vehicles

Use following illustrations to aid in removing and replacing parking brake cables on All Wheel Drive (AWD) vehicles. See - .

Scheme 29

Scheme 30

Scheme 31

Scheme 32

Scheme 33

PARKING BRAKE HANDLE

Use following illustrations to aid in removing and replacing parking brake handle. (Scheme 35)

Scheme 34

CENTER CONSOLE

Removing and installing rear part of center console is necessary for access to parking brake handle. For removal and installation procedures (Scheme 36)- (Scheme 41).

Scheme 35

Scheme 36

Scheme 37

Scheme 38

Scheme 39

Scheme 40

1. Disconnect negative battery cable. Remove master cylinder. See «MASTER CYLINDER»(/audi/a6/c5-1997-2001/remont/mechanical-hydraulic/#brake-system__master-cylinder).
2. Remove trim from under driver's side instrument panel. On vehicles equipped with a manual transmission, remove connecting piece between brake and clutch pedals. Remove brake light switch. See «BRAKELIGHT SWITCH»(/audi/a6/c5-1997-2001/remont/mechanical-hydraulic/#brake-system). Using Release Tool (T10006) disconnect brake pedal from power booster. (Scheme 42)
3. Remove T45 Torx bolts from brake booster. Disconnect vacuum hose from brake booster. Remove power booster and master cylinder.

Scheme 41

To install, reverse removal procedure. Tighten fasteners to specification. See TORQUE SPECIFICATIONS . Adjust brake light and clutch vent valve (if equipped) switches. See BRAKELIGHT SWITCH and CRUISE CONTROL VENT VALVE under ADJUSTMENTS. Bleed brake system. See BLEEDING BRAKE SYSTEM .

1. Raise and support vehicle. Remove wheels. If replacing calipers, disconnect brakeline from caliper, and plug openings. If not replacing calipers, do not disconnect brake line from caliper. Hang brake caliper from body or suspension. Do not allow caliper to hang by brake hose or line.
2. Disconnect parking brake cables. (Scheme 6)- (Scheme 7).
3. On all calipers, remove caliper mounting bolts. Remove caliper assembly from wheel bearing housing. To install, reverse removal procedure. Tighten fasteners to specification. See «TORQUE SPECIFICATIONS»(/audi/a6/c5-1997-2001/remont/mechanical-hydraulic/#brake-system__torque-specifications). Bleed hydraulic brake system. See «BLEEDING BRAKE SYSTEM»(/audi/a6/c5-1997-2001/remont/mechanical-hydraulic/#brake-system) under BLEEDING BRAKE SYSTEM.

Removal (C38)

1. Raise and support vehicle. Remove rear wheels.
2. Disconnect parking brake cable from caliper.
3. Remove guide pins, or caliper mounting bolts. (Scheme 6)
4. Remove caliper, and wire aside. DO NOT allow caliper to hang by brake hose.
5. Remove pads and retaining springs from caliper support.

Installation (C38)

1. Use Special Tool (VW 3272) along with Collar (3272) or equivalent, to seat caliper piston fully into cylinder bore. (Scheme 43)
2. Seat piston by turning special tool until piston is bottomed out in bore.
3. Install brake pads, note positioning of pad to caliper (pin on pad must fit into groove on caliper piston).
4. Position caliper. Install caliper mounting bolts.
5. With engine off, depress brake pedal several times to allow pads to move into operating position.
6. Top off master cylinder reservoir as necessary. Adjust parking brake as necessary. See «PARKING BRAKE»(/audi/a6/c5-1997-2001/remont/mechanical-hydraulic/#brake-system__parking-brake) under ADJUSTMENTS.

Scheme 42

Removal (C43)

1. Raise vehicle. Remove wheels.
2. Secure brake disc with one wheel bolt.
3. Remove securing bolts from brake caliper housing, when doing this counter-hold on guide pins.
4. Remove caliper, and wire aside. DO NOT allow caliper to hang by brake hose.
5. Remove brake pads and retaining springs.
6. Clean brake caliper housing and contact surface for brake pad.

Installation (C43)

1. Use Special Tool (VW 3272) along with Collar (3272/1) or equivalent, to seat caliper piston fully into cylinder bore. (Scheme 43)
2. Insert pad retaining springs.
3. Insert brake pads, making sure brake pads are located correctly in anti-rattle springs. (Scheme 44)
4. Secure brake caliper housing with new self-locking bolts.
5. Ensure brake hose is not twisted when installed on caliper housing.
6. Install wheels. Torque wheel lug bolts to specification. See «TORQUE SPECIFICATIONS»(/audi/a6/c5-1997-2001/remont/mechanical-hydraulic/#brake-system__torque-specifications).
7. Check brake fluid level and top off if necessary.

Scheme 43

1. Raise and support vehicle. Remove wheels. Remove brake calipers. See «REAR CALIPER»(/audi/a6/c5-1997-2001/remont/mechanical-hydraulic/#brake-system) . Slide rotor off hub.
2. To install, reverse removal procedure. Use NEW lock plates (if equipped) and mounting bolts. Tighten to specification. See «TORQUE SPECIFICATIONS»(/audi/a6/c5-1997-2001/remont/mechanical-hydraulic/#brake-system__torque-specifications) . Install wheels and tighten to specification. See «TORQUE SPECIFICATIONS»(/audi/a6/c5-1997-2001/remont/mechanical-hydraulic/#brake-system__torque-specifications) . If hydraulic system was opened, bleed hydraulic brake system. See «BLEEDING PROCEDURES»(/audi/a6/c5-1997-2001/remont/mechanical-hydraulic/#brake-system__bleeding-procedures) under BLEEDING BRAKE SYSTEM.

Disassembly

Remove caliper from vehicle. Remove pads, and clean exterior surfaces. Use air pressure to force piston from cylinder. Use a block of wood between piston and housing to prevent damage to piston. Remove dust seal. Remove piston seal without damaging bore or groove. (Scheme 45)or (Scheme 46).

Scheme 44

Scheme 45

Cleaning & Inspection

Use alcohol or brake cleaning fluid to clean hydraulic chambers. Check cylinder bore and piston for corrosion and damage. Replace defective parts as necessary.

Reassembly

1. Use all parts supplied in repair kit. Coat piston, cylinder bore and NEW seal with clean brake fluid. Fit piston seal into cylinder. Slide dust seal onto piston. Slowly insert piston into bore.
2. Seat inner lip of dust seal in groove on cylinder housing. Open bleed screw and push piston into bore as far as possible. Fit outer lip of dust seal into piston groove.

FRONT CALIPER (HP2, ALUMINUM CALIPER)

Scheme 46

Scheme 47

Scheme 48

Scheme 49

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 48) 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 49)
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 50)
4. Insert piston in hole by hand. Insert brake pad (a) in piston before inserting in brake caliper housing. (Scheme 51) Outer sealing lip of protective cap will then engage in piston groove.

FRONT CALIPER (BREMBO)

Scheme 50

Scheme 51

Scheme 52

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). (Scheme 53) When removing, make sure that surface of brake caliper is not damaged.
4. Remove piston seals using Wedge (3409). (Scheme 54) When removing, make sure that surface of brake caliper is not damaged.

Use alcohol or brake cleaning fluid to clean hydraulic chambers. Check cylinder bore and piston for corrosion and damage. Replace defective parts as necessary.

Note. Apply a thin coat of brake cylinder paste G 052 150 A2, or equivalent, to brake cylinders, pistons and seals before reassembly. Also apply to threads of caliper bleeder valve.

Scheme 53

1. Install piston dust seal (1) on piston (2). Insert piston seal (3) in brake caliper. (Scheme 55)
2. Insert piston into hole by hand. Press brake piston past inner seal by hand. Repeat process for all pistons.

Scheme 54

Scheme 55

1. Unscrew piston from brake caliper housing. (Scheme 57)
2. Remove dust seal from piston. Remove piston seal from rear caliper bore.

Use alcohol or brake parts cleaning fluid for cleaning purposes. Check cylinder bore and piston for wear and corrosion.

Note. Apply a thin coat of brake cylinder paste G 052 150 A2, or equivalent, to brake cylinders, pistons and seals before reassembly. Also apply to threads of caliper bleeder valve.

Scheme 56

Scheme 57

1. Insert inner sealing lip of dust seal using Wedge (3409). Hold piston in front of caliper housing for this procedure. see scheme 58
2. Screw piston into brake caliper housing up to stop. (Scheme 57) Press powerfully on piston while screwing. Outer sealing lip of protective cap will then engage in piston groove.
3. Pre-bleeding brake caliper. Open bleeder valve and fill with brake fluid using standard bleeder bottle until brake fluid flows out of threaded hole (end of brake hose) without bubbles. see scheme 59 Close bleeder screw. Position brake caliper as shown during pre-bleed procedure.

MASTER CYLINDER

Manufacturer recommends replacement of master cylinder if defective.

VACUUM POWER BOOSTER

Manufacturer recommends replacement of vacuum power booster if defective.

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS FRONT (FN3 & FNR-G60)

TORQUE SPECIFICATIONS FRONT (HP2)

TORQUE SPECIFICATIONS FRONT (BREMBO)

TORQUE SPECIFICATIONS REAR (C38 & C43)

DISC BRAKE SPECIFICATIONS

DISC BRAKE SPECIFICATIONS

See also:
• PRODUCTION CODES
• BRAKELIGHT SWITCH
• TORQUE SPECIFICATIONS
• BLEEDING PROCEDURES
• MASTER CYLINDER
• PARKING BRAKE