Disc Brakes Audi A4 B6

MODEL IDENTIFICATION

MODEL IDENTIFICATION

FRONT BRAKE CALIPER IDENTIFICATION

A4 and S4 models are equipped with one of several brake systems. Front 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 front brake caliper Pr. Nos., see A4 & S4 PRODUCTION CODES table.

A4 & S4 PRODUCTION CODES

Scheme 1

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 The brake pressure regulator has been deleted, as it's function has been replaced by ABS control module programming.

BLEEDING PROCEDURES

Recommended Maintenance

Manufacturer recommends changing brake fluid every 2 years.

With & Without Electronic Stability Program (ESP)

Ensure brake master cylinder reservoir is full. 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 brake calipers in sequence. See BRAKELINE BLEEDING SEQUENCE table. Unlike ESP version 5.3, ESP version 5.7 does not incorporate hydraulic pump. Therefore it is not necessary to bleed the system with the diagnostic tester, VAG 1551.

BRAKELINE BLEEDING SEQUENCE

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

BRAKELIGHT SWITCH

Working under dash, remove glove compartment driver's side. (Scheme 2)and (Scheme 3). Disconnect brake light switch harness connector. Remove brake light switch by turning brake switch 45 degrees to left. Pull plunger out as far as possible by hand. (Scheme 4) Being careful not to press down on brake pedal, guide switch into mounting bracket. Turn switch 45 degrees to right. Brake switch adjusts automatically. Connect brake light switch harness connector.

Scheme 2

Scheme 3

Scheme 4

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. Measure distance "A". When measuring, the ball head should be aligned at right angles to the surface of the brake booster. Gasket should NOT be installed when measuring distance. (Scheme 5) Adjust push rod length if not as specified. See POWER BOOSTER PUSH ROD LENGTH table.

POWER BOOSTER PUSH ROD LENGTH

Scheme 5

PARKING BRAKE

Note. The rear brakes are self-adjusting, so it is not necessary to adjust the parking brake. Adjustment is only necessary if the parking brake cables, brake calipers, brake pads and brake discs are replaced.

1. Release parking brake lever. Working at rear brake calipers, use spacers to adjust lever position so that "A" equals.060" (1.5 mm). (Scheme 6)
2. Firmly press and release brake pedal 3 times. Press release button, both snap hooks should catch parking brake cable eyelets. Let release button go. (Scheme 7) Firmly apply parking brake lever 3 times.
3. Press release button, both snap hooks should catch parking brake cable eyelets. Let release button go. Remove spacers from brake calipers. Check lever position at brake calipers. If "A" does not equal.060" (1.5 mm), repeat adjustment.

Scheme 6

Scheme 7

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.

CENTER CONSOLE

Removing and installing rear part of center console is necessary for access to parking brake handle and cables. For removal and installation procedures (Scheme 8)- (Scheme 18).

Scheme 8

Scheme 9

Scheme 10

Scheme 11

Scheme 12

Scheme 13

Scheme 14

Scheme 15

Scheme 16

Scheme 17

Scheme 18

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 19)- (Scheme 21). Remove caliper assembly from wheel bearing housing.
3. To install, reverse removal procedure. Tighten fasteners to specification. See «TORQUE SPECIFICATIONS»(/audi/a4/b6-2000-2006/remont/mechanical-hydraulic/#disc-brakes__torque-specifications). Bleed hydraulic brake system. See «BLEEDING BRAKE SYSTEM»(/audi/a4/b6-2000-2006/remont/mechanical-hydraulic/#disc-brakes) under BLEEDING BRAKE SYSTEM.

Scheme 19

Scheme 20

Scheme 21

Removal (FN3)

1. Raise and support vehicle. Remove front wheels. Remove guide pin protective caps. (Scheme 19) Pry brake pad retaining spring out from brake caliper housing with a screwdriver and remove. Disconnect brake pad wear indicator harness connector (if equipped).
2. Remove both guide pins from brake caliper. Remove brake caliper housing and secure with wire so that the weight of the brake caliper does not stress or damage brake hose. Remove brake pads from brake caliper housing.

Installation (FN3)

1. Before inserting new brake pads, press piston back into the cylinder with piston resetting tool. Before pressing the piston back, draw off brake fluid from the reservoir with a bleeder bottle. Otherwise if reservoir has been topped off, fluid will overflow and cause damage to finish.
2. Install brake pad with retaining spring into brake caliper piston. The inner pad (with expansion spring) has an arrow. The arrow should point in the direction of rotation of the brake disc when travelling forward. If installed incorrectly this may cause noise problems. Pull off protective sheet on backing plate of outer brake pad. Install outer brake pad onto brake carrier.
3. Install brake caliper housing with brake pads on wheel bearing housing, lower part of brake caliper first. Brake caliper housing lug must be behind the wheel bearing housing guide. Secure brake caliper housing to brake carrier with both guide pins and tighten to specification. See «TORQUE SPECIFICATIONS»(/audi/a4/b6-2000-2006/remont/mechanical-hydraulic/#disc-brakes__torque-specifications) .
4. Connect brake pad wear indicator harness connector. After brake pad change firmly depress brake pedal several times with vehicle stationary, so that the brake pads are properly seated. Check brake fluid level.

Removal (C54)

1. Raise and support vehicle. Remove front wheels.
2. Disconnect brake pad wear indicator harness connector. Lift locking tab slightly, turn 90° and remove harness connector from bracket.
3. Unscrew lower mounting bolt for brake caliper housing. (Scheme 20)
4. Remove lower caliper-to-brake pad carrier bolt (counter-holding at guide pin). Swing brake caliper housing upward and remove brake pads.

Installation (C54)

Note. Before pressing the piston back, draw off brake fluid from the reservoir with a bleeder bottle. Otherwise if reservoir has been topped off, fluid will overflow and cause damage.

1. Before inserting new brake pads, press piston back into the cylinder with piston resetting tool.
2. Insert brake pads.
3. Swing brake caliper housing downward and tighten mounting bolts to specification. See «TORQUE SPECIFICATIONS»(/audi/a4/b6-2000-2006/remont/mechanical-hydraulic/#disc-brakes__torque-specifications) .
4. Repair kit includes two self-locking hex-bolts which must always be installed.
5. Connect brake pad wear indicator harness connector. After brake pad change firmly depress brake pedal several times with vehicle stationary, so that the brake pads are properly seated. Check brake fluid level.

Removal (FNR-G60)

1. Raise and support vehicle. Remove front wheels. Secure brake disc with a wheel bolt.
2. Using flat-bladed tool, pry off brake pad retaining spring from brake caliper housing and remove. (Scheme 21) Disconnect brake pad wear indicator harness connector. Using a flat-bladed tool, release harness connector from the holder by turning connector by 90 degrees. Pull connector out upward and unhook the wire.
3. Detach brake line from bracket. Remove trim cap, unscrew 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.

Installation (FNR-G60)

Note. Before pressing the piston back, draw off brake fluid from the reservoir with a bleeder bottle. Otherwise if reservoir has been topped off, fluid will overflow and cause damage.

1. To install pads, press piston back into caliper housing using resetting tool.
2. 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/a4/b6-2000-2006/remont/mechanical-hydraulic/#disc-brakes__torque-specifications) .
3. 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.
4. Install wheels and tighten to specification. See «TORQUE SPECIFICATIONS»(/audi/a4/b6-2000-2006/remont/mechanical-hydraulic/#disc-brakes__torque-specifications) .
5. 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.

Raise and support vehicle. Remove wheels. Remove brake caliper. See FRONT & REAR BRAKE CALIPER . Secure caliper with wire so that the weight of the brake caliper does not stress or damage brake hose. Remove countersunk screw that holds rotor to hub. Pull rotor off hub. To install, reverse removal procedure. Apply a small amount of polycarbamide grease (G 052 142 A2) to contact surfaces between brake disc and wheel hub. Tighten fasteners to specification. See TORQUE SPECIFICATIONS .

Removal

Note. Master cylinder and power booster must be removed together.

1. Working under dash, remove driver's side accessory tray. (Scheme 2)and (Scheme 3). Remove brake light switch harness connector. Turn switch 45 degrees counter clockwise, and remove switch.
2. Using Release Tool (T40024), separate brake pedal from power booster. (Scheme 22)
3. Working under hood, remove appropriate engine covers. Disconnect brake fluid level sensor harness connector. Disconnect vacuum hose. Using bulb type suction device, remove as much brake fluid as possible from reservoir. Remove brake fluid reservoir retaining bolt. Remove bolt connecting reservoir to master cylinder and remove reservoir from master cylinder. DO NOT allow brake fluid to contact painted surfaces.
4. Disconnect steel hydraulic lines at master cylinder, and plug ports to prevent fluid spillage. Remove master cylinder/booster mounting bolts. (Scheme 23) Remove master cylinder-to-booster nuts. Separate master cylinder from power booster.

Scheme 22

Scheme 23

Installation

Before installing master cylinder, clean residual brake fluid from power booster. Ensure push rod is properly centered in master cylinder. To install, reverse removal procedure. Tighten fasteners to specification. See TORQUE SPECIFICATIONS . Adjust brake light switch. See BRAKELIGHT SWITCH under ADJUSTMENTS. Bleed brake system. See BLEEDING BRAKE SYSTEM .

1. The parking brake cable adjusting elements are located in front of the rear lower transverse links. Remove center console extension. See «CENTER CONSOLE»(/audi/a4/b6-2000-2006/remont/mechanical-hydraulic/#disc-brakes__center-console).
2. Raise and support vehicle. Remove wheels. Unhook exhaust at rear. Detach heat shield at rear of tank. Detach rear tunnel heat shield (underneath the drive shaft). Detach rear tunnel heat shield (above the drive shaft).
3. Pull out retaining washer and detach parking brake cables at brake caliper. DO NOT damage parking brake boot when detaching and attaching. Unclip brake cable (1) from retainer (3). (Scheme 24)
4. Unclip brake cable from retainer. Unclip brake cables from retainers (2) and (4). (Scheme 24) The parking brake lever has to be removed and the mechanism reset before it is possible to install new parking brake cables. See «PARKING BRAKE HANDLE»(/audi/a4/b6-2000-2006/remont/mechanical-hydraulic/#disc-brakes).

Scheme 24

1. Clip parking brake cable on to parking brake lever as far as it will go. Clip loop on retainer must be located between two positioning rings (5). (Scheme 25) Clip point on retainer (4) must always point toward the outside of the vehicle.
2. Hook cable to exhaust mounting. Attach parking brake cables to underbody and tank. Connect cable to lever at brake caliper. DO NOT damage parking brake boot when detaching and attaching. Hook parking brake cable into brake caliper and insert retaining washer.
3. Cable positioning rings must be located within clip points on the retainer. Attach heat shields. Adjusting parking brake. See «PARKING BRAKE»(/audi/a4/b6-2000-2006/remont/mechanical-hydraulic/#disc-brakes__parking-brake) under ADJUSTMENTS.
4. Install center console extension.
5. Install wheels. Tighten wheel lug bolts to specification. See «TORQUE SPECIFICATIONS»(/audi/a4/b6-2000-2006/remont/mechanical-hydraulic/#disc-brakes__torque-specifications).

Scheme 25

1. Remove center console extension. See «CENTER CONSOLE»(/audi/a4/b6-2000-2006/remont/mechanical-hydraulic/#disc-brakes__center-console).
2. Raise and support vehicle. Working under vehicle, detach the underside panelling on the left and right rear. Unclip parking brake cables, at parking brake handle.
3. Unhook the left underside panelling, approximately 8 bolts.
4. Detach the inside of the underside panelling at the exhaust. Unhook exhaust at rear.
5. Pull out retaining washer (1) and detach the parking brake cables at brake calipers. (Scheme 26) Unclip brake line (2) from retainers (3).
6. Unclip the parking brake cables (1) from the fuel tank clip (2). (Scheme 27)or (Scheme 28). Unclip the parking brake cables (3) from the retainer (4). The parking brake lever has to be removed and the mechanism reset before it is possible to install new parking brake cables. See «PARKING BRAKE HANDLE»(/audi/a4/b6-2000-2006/remont/mechanical-hydraulic/#disc-brakes).

Scheme 26

Scheme 27

Scheme 28

Scheme 29

1. Connect clip on the parking brake cable as far as it will go. At the cable crossover point, cable (1) must lie underneath cable (2). (Scheme 29) Clip cable into the designated retainers.
2. The clip loop on the retainer must be located between the two positioning rings (4). Tighten cable bracket bolt to 18 ft. lbs. (25 N.m).
3. Secure the parking brake cables on the underbody and tank. Be careful not to damage parking brake bellows when detaching and attaching cables. Hook the parking brake cable into the brake caliper and insert the retaining washer.
4. Ensure cable positioning rings are located within the clip points on the retainer. Attach the heat shields. Install center console extension. Adjusting parking brake.

1. Remove center console extension. See «CENTER CONSOLE»(/audi/a4/b6-2000-2006/remont/mechanical-hydraulic/#disc-brakes__center-console). Release the parking brake handle (1) with a screwdriver (3) and pull it off. (Scheme 30)
2. Pull off the cover (4) and the handle (1). (Scheme 31) Remove the hexagon bolts (2) and remove from support (1). (Scheme 32)
3. With two cables hooked into handle insert a screwdriver into the release opening. Press screwdriver in the direction of "center adjustment". Hold screwdriver pressed in this position and slowly operate the parking brake lever. Ensure that the cable eyelets do not jump off the hooks. Remove screwdriver. Unhook the parking brake cables.
4. With one cable hooked in release the mechanism with a screwdriver (2), at the same time press back the second snap hook (1) with a screwdriver. (Scheme 33)
5. Remove flange nuts (1). (Scheme 34) Disconnect parking brake contact switch. Remove parking brake lever (2) from console. Pushing downward remove parking brake lever.

Scheme 30

Scheme 31

Scheme 32

Scheme 33

Scheme 34

Resetting Adjustment Mechanism

1. Clamp one of the snap hooks into a vice. Release the mechanism with a screwdriver (2), at the same time press back the second snap hook with a screwdriver. (Scheme 35)

Scheme 35

1. Installation is reverse of removal. Install center console extension. Tighten both nuts (1) finger tight. The rear nut can be accessed through the ashtray opening, and the front one through a cut-out in the bottom of the storage shelf.
2. Align the parking brake cable so that it is in the middle of the recess for the center console. (Scheme 36) Tighten nuts to 18 ft. lbs. (25 N.m). Adjust parking brake. See «PARKING BRAKE»(/audi/a4/b6-2000-2006/remont/mechanical-hydraulic/#disc-brakes__parking-brake) under ADJUSTMENTS.

Scheme 36

POWER BOOSTER

Note. Master cylinder and power booster must be removed together. See MASTER CYLINDER .

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. Bend back locking tabs (if equipped) on mounting bolts. If removing rear brake calipers, disconnect parking brake cables. (Scheme 37)- (Scheme 38).
3. On all calipers, remove caliper mounting bolts. Remove caliper assembly from wheel bearing housing. To install, reverse removal procedure. Use NEW lock plates (if equipped) and mounting bolts. Bleed hydraulic brake system. See «BLEEDING BRAKE SYSTEM»(/audi/a4/b6-2000-2006/remont/mechanical-hydraulic/#disc-brakes) under BLEEDING BRAKE SYSTEM.

Scheme 37

Scheme 38

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 37)
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 39)
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/a4/b6-2000-2006/remont/mechanical-hydraulic/#disc-brakes__parking-brake) under ADJUSTMENTS.

Scheme 39

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 39)
2. Insert pad retaining springs.
3. Insert brake pads, making sure brake pads are located correctly in anti-rattle springs. (Scheme 40)
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/a4/b6-2000-2006/remont/mechanical-hydraulic/#disc-brakes__torque-specifications).
7. Check brake fluid level and top off if necessary.

Scheme 40

FRONT CALIPER

Note. Black staining from piston seal wear may show on caliper bore walls and piston. This staining is normal.

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 41)

Scheme 41

Scheme 42

Scheme 43

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 a thin coat of assembly paste or 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.

REAR CALIPER

Note. Black staining from piston seal wear may show on caliper bore walls and piston. This staining is normal.

Note. Overhaul procedures for C43 system were available from manufacturer.

Disassembly (C38)

Remove pads, and clean outside surfaces. Use Special Tool (VW 3272) or equivalent, unscrew piston from cylinder. (Scheme 39) Carefully remove piston seal without damaging bore or groove. (Scheme 44)

Scheme 44

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

Reassembly (C38)

Use all parts supplied in repair kit. Coat piston, cylinder bore and NEW seal with a thin coat of assembly paste or brake fluid. Fit piston seal into cylinder. Slide dust seal into groove on piston. Press down on piston while screwing it into cylinder bore using Special Tool (VW 3272). Ensure outer lip of dust seal slips into piston groove.

MASTER CYLINDER

Manufacturer recommends replacement of master cylinder if defective.

VACUUM POWER BOOSTERS

Manufacturer recommends replacement of vacuum power booster if defective.

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

DISC BRAKE SPECIFICATIONS

DISC BRAKE SPECIFICATIONS

See also:
• A4 & S4 PRODUCTION CODES
• TORQUE SPECIFICATIONS
• BRAKELIGHT SWITCH
• CENTER CONSOLE
• PARKING BRAKE
• MASTER CYLINDER