Disc Brakes Audi A4 B5

MODEL IDENTIFICATION

MODEL IDENTIFICATION

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 The brake pressure regulator has been deleted, as its function has been replaced by ABS control module programming.

BLEEDING PROCEDURE

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.

BRAKELINE BLEEDING SEQUENCE

Pedal Bracket With Internal Thread For Brake Light Switch

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

Scheme 1

Pedal Bracket With Spring Clip For Brake Light Switch

The swith must installed only ONCE to ensure it is adequately tight. Insert switch into installed clip and press in to step. (Scheme 2)After adjustment, brake pedal must not be under preload. If necessary, turn switch back slightly, noting clearance

Scheme 2

CRUISE CONTROL SYSTEM VENT VALVES

Note. Only install the cruise control brake pedal and clutch pedal vent valves ONE time, otherwise an adequately tight fit cannot be assured.

With the brake and/or clutch pedal in the released position, Insert vent valve into the bracket as far as the stop with a 10mm box wrench. Do NOT rotate it in.. Push back valve by pulling back brake pedal or clutch pedal to stop. For 1996-97 models, procedure is complete.

For 1998 and newer models, a new design bracket is installed. After installation, dimension "a" must be.028" (0.7 mm). (Scheme 4)

Scheme 3

Scheme 4

POWER BOOSTER PUSH ROD

Note. Power booster push rod may also be known as ball head adjustment.

Adjustment

Measure push rod length whenever power booster or master cylinder is replaced. Push rod length is measured from mounting flange to end of ball head. Measure distance "A". Ball head must be at right angles to brake booster mounting flange when measuring. Measure with NO gasket installed. (Scheme 5) Adjust push rod length if not as specified. See POWER BOOSTER PUSH ROD LENGTH table.

Scheme 5

POWER BOOSTER PUSH ROD LENGTH

PARKING BRAKE

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

Scheme 6

Scheme 7

Scheme 8

Scheme 9

1. Press brake pedal firmly. Remove rear passenger compartment ashtray. Use flat-bladed tool to prevent compensator from turning. (Scheme 6) 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. (Scheme 6)
3. On all models, remove locking clip "D". (Scheme 7)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 8) 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 9) Lever should not contact brake caliper. Gap should be visible but no wider than 0.059" (1.5 mm).

Front

All wheel bearings are press fit into wheel bearing housing and require no lubrication or adjustment. Replace wheel bearing if failure occurs. Wheel bearing must be replaced if removed from housing. See appropriate article in SUSPENSION.

Rear (Quattro)

All wheel bearings are press fit into wheel bearing housing and require no lubrication or adjustment. Replace wheel bearing if failure occurs. See appropriate article in SUSPENSION.

Rear (Except Quattro)

Raise and support vehicle. Remove grease cap, cotter pin and castle nut. While turning wheel, tighten spindle nut to 89 INCH lbs. (10 N.m). Insert tip of screwdriver between thrust washer and hub. Back off nut until light finger pressure against screwdriver just moves thrust washer. Install castle nut, NEW cotter pin and grease cap. For further repair procedures, see appropriate article in SUSPENSION.

Dual Piston Front Calipers

Warning light on instrument panel will come on when front brake pad wear limit is reached. Replacing front brake pads will turn out light.

MASTER CYLINDER LEAKAGE TEST

If leakage is suspected in hydraulic system, perform leak test as follows

1. Ensure brake system (hydraulic unit, brake hoses, brake lines and brake calipers) is operating properly and free of leaks.
2. Remove bleeder screw at one front brake caliper. Connect Pressure Gauges (VAG 1310 or VW 1310) to left front caliper and right rear caliper. Bleed pressure gauges and hoses through bleed screws on gauges. Insert brake pedal depressor between brake pedal and driver's seat. Apply pressure to brake pedal until gauge indicates pressure of 725 psi (50 bar).
3. The pressure must drop by no more than 58 psi (4 bar) during the test period of 45 seconds. If the pressure drop is more than specified, replace brake master cylinder. See «MASTER CYLINDER»(/audi/a4/b5-1994-1999/remont/mechanical-hydraulic/#disc-brakes__master-cylinder) under REMOVAL & INSTALLATION.

RECOMMENDED BRAKE FLUID CHANGE INTERVAL

Manufacturer recommends replacing brake fluid every 2 years. This also applies to hydraulic clutch fluid on vehicles with manual transmission.

Note. On models with Electronic Stability Program (ESP), hydraulic pump can only be bled using factory scan tool. Hydraulic pump is actuated for 10 seconds

REMOVAL & INSTALLATION

Note. Before disconnecting battery, on vehicles equipped with coded anti-theft radio, note radio code. Obtain if necessary.

CENTER CONSOLE

Removing and installing rear part of center console is necessary for access to parking brake handle. For removal and installation procedures (Scheme 10)and (Scheme 11).

Scheme 10

Scheme 11

FRONT BRAKE CALIPER

Removal & Installation (Single Piston)

1. Raise and support vehicle. Remove wheels.
2. Remove caliper guide pin caps and guide pins. (Scheme 31) Remove caliper assembly from caliper carrier.
3. If not replacing caliper DO NOT allow caliper to hang by brake hose. Unsupported weight can stretch and damage hose. If removing caliper, disconnect and plug brake line.
4. To install, reverse removal procedure. Tighen guide pins to specification. See «TORQUE SPECIFICATIONS»(/audi/a4/b5-1994-1999/remont/mechanical-hydraulic/#disc-brakes__torque-specifications). If necessary, bleed brakes. See «BLEEDING PROCEDURES»(/audi/a4/b5-1994-1999/remont/mechanical-hydraulic/#disc-brakes__bleeding-procedure) under BLEEDING BRAKE SYSTEM.

Removal & Installation (Dual Piston)

1. Raise and support vehicle. Remove wheels.
2. Remove caliper mounting ribbed bolts. (Scheme 14)
3. Lift caliper from mount. If not replacing caliper DO NOT allow caliper to hang by brake hose. Unsupported weight can stretch and damage hose. If removing caliper, disconnect and plug brake line.
4. To install reverse removal procedure. If reusing original brake pads, install in original position. If re-using, clean ribbed bolts. Tighen caliper mounting ribbed bolts to specification. See «TORQUE SPECIFICATIONS»(/audi/a4/b5-1994-1999/remont/mechanical-hydraulic/#disc-brakes__torque-specifications). If necessary, bleed brakes. See «BLEEDING PROCEDURES»(/audi/a4/b5-1994-1999/remont/mechanical-hydraulic/#disc-brakes__bleeding-procedure) under BLEEDING BRAKE SYSTEM.

FRONT BRAKE PADS

Note. If brake pads are to be re-used, mark their installed positions when removing. Install in same position or car may pull to one side.

Removal (Single Piston Caliper)

1. Raise and support vehicle. Remove front wheels. Remove guide pin protective caps. (Scheme 31) Pry brake pad retaining spring out from brake caliper housing with a screwdriver and remove.
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 (Single Piston Caliper)

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 to finish.

1. Before inserting new brake pads, press piston back into the cylinder.
2. Install inner brake pad (with expanding spring) in brake caliper piston. Arrow marked on pad must point in direction of rotor rotation when vehicle is moving forward.
3. Remove protective sheet from backing plate for outer brake pad. Install outer brake pad into brake carrier. Bolt brake caliper housing to brake carrier using two guide pins. Tighten guide pins to specification. See «TORQUE SPECIFICATIONS»(/audi/a4/b5-1994-1999/remont/mechanical-hydraulic/#disc-brakes__torque-specifications) .
4. Install both caps. Insert retaining spring into brake caliper housing. Once spring ends are seated in holes, press retaining spring under brake carrier.
5. 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 (Dual Piston Caliper)

Scheme 12

Scheme 13

1. Raise vehicle. Remove wheels. Secure brake disc with wheel bolt. Remove both Torx bolts for outer brake pads. (Scheme 12)
2. Push piston back into brake caliper housing. To do this use screwdriver inserted into floating caliper frame and press frame outward. Remove outer brake pads first by pressing pads off brake caliper using screwdriver.
3. Press floating frame in direction of left arrows as far as stop. (Scheme 13) Carefully press brake pads out of pistons using screwdriver (right arrow) and remove from caliper housing.

Scheme 14

Scheme 15

Scheme 16

1. Thoroughly clean the brake caliper housing before installing the new brake pads. Pay particular attention to cleaning the residues left from the outer brake pad adhesive.
2. Install bottom and top brake pads into pistons. Do not damage the protective boots when installing the brake pads. (Scheme 15)
3. Press floating frame out as far as stop. (Scheme 16) Remove protective sheet from back of outer brake pads.
4. Install Torx bolts from repair kit into floating frame to secure outer brake pads in position. Tighten to specification. See «TORQUE SPECIFICATIONS»(/audi/a4/b5-1994-1999/remont/mechanical-hydraulic/#disc-brakes__torque-specifications). Remove wheel bolt from wheel hub. Install wheels.
5. Connect brake pad warning light wiring connector (if equipped).
6. After brake pad change, firmly depress brake pedal several times with vehicle stationary, so that the brake pads are properly seated in their normal operating position. Check brake fluid level.

Raise and support vehicle. Remove wheels. Remove brake caliper. See FRONT BRAKE CALIPER or REAR BRAKE CALIPER . Secure caliper with wire so that the weight of the brake caliper does not stress or damage brake hose. Remove screw that holds rotor to hub. Pull rotor off hub. To install, reverse removal procedure. Tighten fasteners to specification. See TORQUE SPECIFICATIONS .

Scheme 17

Scheme 18

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. (Scheme 17)
3. Disconnect brake lines on brake master cylinder and seal brake lines and threaded holes with plugs. (Scheme 18) Remove brake master cylinder mounting nuts. Remove brake Carefully remove brake master cylinder from brake booster unit.

Installation - With 0.937" (23.81 mm) Diameter Piston

1. To install, reverse removal procedure.
2. When installing brake master cylinder onto brake servo, make sure push rod is correctly located in brake master cylinder. Apply slight pressure to brake pedal to move push rod toward brake master cylinder; this makes it easier to guide brake master cylinder onto push rod.
3. Tighten fasteners to specification. See «TORQUE SPECIFICATIONS»(/audi/a4/b5-1994-1999/remont/mechanical-hydraulic/#disc-brakes__torque-specifications) .

Bleed hydraulic system. See BLEEDING PROCEDURES under BLEEDING BRAKE SYSTEM.

Removal - With .999" (25.4 mm) Diameter Piston & Brake Servo

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

Scheme 19

1. Working under dash, remove driver's side accessory tray. Remove brake light switch harness connector. Turn switch 45 degrees counterclockwise, and remove switch.
2. Using Release Tool (T40024), separate brake pedal from power booster. (Scheme 19)
3. Remove appropriate under hood engine covers. Disconnect brake fluid level sensor harness connector. Disconnect vacuum hose.
4. Disconnect steel hydraulic lines at master cylinder, and plug ports to prevent fluid spillage. Remove power booster Torx bolts. Remove master cylinder-to-booster nuts. Separate master cylinder from power booster.

Installation - With .999" (25.4 mm) Diameter Piston & Brake Servo

1. Before installing master cylinder, clean residual brake fluid from power booster. Ensure push rod is properly centered in master cylinder.
2. To install, reverse removal procedure. Tighten fasteners to specification. See «TORQUE SPECIFICATIONS»(/audi/a4/b5-1994-1999/remont/mechanical-hydraulic/#disc-brakes__torque-specifications) .
3. Bleed hydraulic system. See «BLEEDING PROCEDURES»(/audi/a4/b5-1994-1999/remont/mechanical-hydraulic/#disc-brakes__bleeding-procedure) under BLEEDING BRAKE SYSTEM. Adjust brake light switch. See «BRAKELIGHT SWITCH»(/audi/a4/b5-1994-1999/remont/mechanical-hydraulic/#disc-brakes) under ADJUSTMENTS. Adjust cruise control vent valve. See «CRUISE CONTROL SYSTEM VENT VALVES»(/audi/a4/b5-1994-1999/remont/mechanical-hydraulic/#disc-brakes__cruise-control-system-vent-valves) under ADJUSTMENTS.

FWD Vehicles

Use following illustrations to aid in removing and replacing parking brake cables on FWD vehicles. (Scheme 20)- (Scheme 24).

Scheme 20

Scheme 21

Scheme 22

Scheme 23

Scheme 24

AWD Vehicles

Use following illustrations to aid in removing and replacing parking brake cables on AWD vehicles. (Scheme 25)- (Scheme 28).

Scheme 25

Scheme 26

Scheme 27

Scheme 28

PARKING BRAKE HANDLE

Use following illustration to aid in removing and replacing parking brake handle. (Scheme 29)

Scheme 29

POWER BOOSTER

Note. For brake system with .999" (25.4 mm) diameter piston master cylinder, see REMOVAL - WITH .999" (25.4 MM) DIAMETER PISTON & BRAKE SERVO under MASTER CYLINDER.

Removal - With .937" (23.81 mm) Piston Diameter Master Cylinder

1. Disconnect negative battery cable. Clamp and remove clutch master cylinder supply hose, if equipped. Disconnect power booster vacuum supply line.
2. Remove master cylinder. See «REMOVAL - WITH 0.937" (23.81 MM) DIAMETER PISTON»(/audi/a4/b5-1994-1999/remont/mechanical-hydraulic/#disc-brakes) under MASTER CYLINDER.
3. Remove trim from under driver's side instrument panel. On vehicles equipped with a manual transmission, remove connecting piece between brake and clutch pedals. Disconnect brake light switch harness connector. Remove brake light switch by turn switch counterclockwise 90 degrees.
4. Using Release Tool (T10006), disconnect brake pedal from power booster. (Scheme 19) Remove fasteners holding power booster and master cylinder to firewall. Remove power booster and master cylinder.

Installation - With .937" (23.81 mm) Piston Diameter Master Cylinder

1. Before installing master cylinder, clean residual brake fluid from power booster. Ensure push rod is properly centered in master cylinder.
2. To install, reverse removal procedure. Tighten fasteners to specification. See «TORQUE SPECIFICATIONS»(/audi/a4/b5-1994-1999/remont/mechanical-hydraulic/#disc-brakes__torque-specifications) .
3. Adjust brake light switch. See «BRAKELIGHT SWITCH»(/audi/a4/b5-1994-1999/remont/mechanical-hydraulic/#disc-brakes) under ADJUSTMENTS. Bleed brake system. See «BLEEDING PROCEDURES»(/audi/a4/b5-1994-1999/remont/mechanical-hydraulic/#disc-brakes__bleeding-procedure) under BLEEDING BRAKE SYSTEM. Adjust cruise control vent valve. See «CRUISE CONTROL SYSTEM VENT VALVES»(/audi/a4/b5-1994-1999/remont/mechanical-hydraulic/#disc-brakes__cruise-control-system-vent-valves) under ADJUSTMENTS.

REAR BRAKE CALIPER

1. Raise and support vehicle. Remove wheels. If replacing caliper, disconnect brakeline from caliper, and plug openings.
2. Remove caliper-to-carrier self-locking bolts. Counter-hold guide pin when loosening and tightening.
3. Lift off caliper. If removing rear brake calipers, disconnect parking brake cables.Disconnect and plug brake line. If not replacing caliper DO NOT allow caliper to hang by brake hose. Unsupported weight can stretch and damage hose.
4. To install, reverse removal procedure. If reusing original brake pads, install in original position. Use NEW mounting bolts. If necessary, bleed hydraulic brake system. See «BLEEDING PROCEDURES»(/audi/a4/b5-1994-1999/remont/mechanical-hydraulic/#disc-brakes__bleeding-procedure) under BLEEDING BRAKE SYSTEM.

REAR BRAKE PADS

Removal

Raise and support vehicle. Remove rear wheels. Disconnect parking brake cable from caliper. Remove guide pins, or caliper mounting bolts. (Scheme 30) Remove caliper, and wire aside. DO NOT allow caliper to hang by brake hose. Remove pads and retaining springs from caliper support.

Scheme 30

Installation (Except Aluminum Rear Calipers)

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 to finish.

1. Use Special Tool (VW 3272), to seat caliper piston fully into cylinder bore. (Scheme 33) Seat piston by turning special tool until piston is bottomed out in bore.
2. Install rear brake pads in brake caliper carrier. Install brake caliper. Tighten bolts to specification. See «TORQUE SPECIFICATIONS»(/audi/a4/b5-1994-1999/remont/mechanical-hydraulic/#disc-brakes__torque-specifications).
3. With engine off, depress brake pedal several times to allow pads to move into operating position. Top off master cylinder reservoir as necessary. Adjust parking brake as necessary. See «PARKING BRAKE»(/audi/a4/b5-1994-1999/remont/mechanical-hydraulic/#disc-brakes__parking-brake) under ADJUSTMENTS.

Installation (Aluminum Rear Calipers)

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 to finish.

1. Use Special Tool (VW 3272) along with Collar (3272/1) or equivalent, to seat caliper piston fully into cylinder bore. (Scheme 34) Seat piston by turning special tool until piston is bottomed out in bore.
2. Remove protective foil from brake pad backing plate.Install brake pads in brake carrier.
3. Install brake caliper housing with new self-locking bolts and tighten to specification. See «TORQUE SPECIFICATIONS»(/audi/a4/b5-1994-1999/remont/mechanical-hydraulic/#disc-brakes__torque-specifications).
4. With engine off, depress brake pedal several times to allow pads to move into operating position. Top off master cylinder reservoir as necessary. Adjust parking brake as necessary. See «PARKING BRAKE»(/audi/a4/b5-1994-1999/remont/mechanical-hydraulic/#disc-brakes__parking-brake) under ADJUSTMENTS.

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. See FRONT & REAR BRAKE CALIPER in REMOVAL & INSTALLATION. 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 31)

Scheme 31

Scheme 32

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.

Scheme 33

Scheme 34

1. Remove caliper from vehicle. See «FRONT & REAR BRAKE CALIPER»(/audi/a4/b5-1994-1999/remont/mechanical-hydraulic/#disc-brakes__front-brake-caliper) in REMOVAL & INSTALLATION.Remove pads, and clean outside surfaces.
2. For non-aluminum calipers, use Special Tool (VW 3272) to unscrew piston from caliper. (Scheme 33) On aluminum calipers, use Special Tool (VW 3272) along with Collar (3272/1) or equivalent to unscrew piston from cylinder. (Scheme 34) Remove piston by turning threaded spindle counterclockwise and knurled section clockwise.

On both type calipers, carefully remove piston seal without damaging bore or groove. (Scheme 35)

Scheme 35

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

Scheme 36

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 into groove on piston.
2. Press down on piston while screwing it into cylinder bore. On aluminum caliper, install piston by turning threaded spindle clockwise and knurled section counterclockwise.On both types of caliper, turn Ensure outer lip of dust seal slips into piston groove.
3. Position brake caliper for pre-bleeding. (Scheme 36)Open bleed valve and fill with brake fluid until fluid flows out of threaded hole (brake hose connection) free of bubbles.

MASTER CYLINDER

Manufacturer recommends replacement of master cylinder if defective.

Manufacturer recommends replacement of power booster if defective.

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS (SINGLE PISTON CALIPER EQUIPPED)

TORQUE SPECIFICATIONS (DOUBLE PISTON CALIPER EQUIPPED)

DISC BRAKE SPECIFICATIONS

DISC BRAKE SPECIFICATIONS (SINGLE PISTON CALIPER EQUIPPED)

DISC BRAKE SPECIFICATIONS (DOUBLE PISTON CALIPER EQUIPPED)

See also:
• BRAKELINE BLEEDING SEQUENCE
• MASTER CYLINDER
• TORQUE SPECIFICATIONS
• BLEEDING PROCEDURES
• FRONT BRAKE CALIPER
• REAR BRAKE CALIPER
• CRUISE CONTROL SYSTEM VENT VALVES
• REMOVAL - WITH .999" (25.4 MM) DIAMETER PISTON & BRAKE SERVO
• PARKING BRAKE