Brakes - Repair BMW Z4 E85/E86

DESCRIPTION & OPERATION

Note. For information on Anti-Lock Brake Systems (ABS), see ANTI-LOCK/TRACTION CONTROL article.

Brake system is hydraulically-operated, using a tandem master cylinder and power brake booster. All models are equipped with single piston front and rear disc brake calipers. A brake pressure regulator is used to reduce fluid pressure to rear brakes.

Parking brake is cable actuated on rear brake and consists of internally mounted parking brake shoes. Basic adjustment of the parking brake is required whenever

1. Brake shoes are replaced.
2. Brake discs are replaced.
3. Bowden cable is replaced.
4. Bowden cable guide tube is replaced.
5. Adjusting unit is reset.
6. Actuating stroke is excessive.

AUTOMATIC CABLE ADJUSTER (ASZE UNIT)

The ASZE unit provides automatic cable adjustments (for normal stretch) and is located in the mounting pan. The ASZE unit consists of cable tensioning spring, rack extension, locking clip and hook. The ASZE unit holds both cables under equal tension via a balance arm. Parking brake lining wear is not compensated by the ASZE unit. Traditional adjustments at the wheels are still necessary.

BASIC BLEEDING PROCEDURES

1. If using a bleeder device, refer to documentation. Attach to expansion tank. Charging pressure must not exceed 29 psi (2 bar).
2. Reservoir on master cylinder must be full at start of bleeding procedure. Connect bleeder hose with bottle to right rear brake caliper. Open bleed valve and fully depress brake pedal at least 12 times. Brake fluid must emerge without bubbles.
3. Apply steady pressure and close bleeder valve.
4. Switch off bleeder unit and disconnect from expansion tank. Check brake fluid level. Close expansion tank. Take care of rubber gasket in lid.
5. Repeat procedure on left rear brake caliper, right front brake caliper and left front brake caliper.

VEHICLES WITH ABS/ASC+T

Perform the following filling and bleeding procedure when exchanging or repairing tandem-brake master cylinder, hydraulic unit ABS/ASC+T and components, or connecting lines installed between these units.

When carrying out any other work on the brake system (e.g. replacing brake calipers), see BASIC BLEEDING PROCEDURES .

Note. Bleeding unit is connected with maximum 29 psi (2 bar) filling pressure.

Note. Check relevant operating instructions for each device.

1. Connect bleeder hose with collecting tray to bleeder valve on right rear brake caliper. Open bleeder valve and purge until clear, bubble-free brake fluid emerges.
2. Close bleeder valve. Follow same procedure on wheel brakes at left rear, right front and left front, in that order.
3. Switch off bleeder unit and disconnect from expansion tank.
4. Check brake fluid level.
5. Close expansion tank. Take care of rubber gasket in lid.

VEHICLES WITH DYNAMIC STABILITY CONTROL (DSC)

Note. Check relevant operating instructions for each device.

Perform the following filling and bleeding procedure when exchanging or repairing tandem-brake master cylinder, hydraulic control unit for Dynamic Stability Control (DSC) and components, or connecting lines installed between these units. When carrying out any other work on brake system (e.g. replacing brake calipers), see BASIC BLEEDING PROCEDURES .

After work has been completed on the precharging pump, only the front-axle brake circuit has to be bled. Activate precharging pump once with Diagnosis and Information System (DIS). (Brake fluid changer connected to maximum 2 bar filling pressure). After completing work, carry out final check with DIS under menu item SERVICE FUNCTIONS. Contrary to the instructions in the DIS, the bleeding routine must be restarted on each wheel. A second person is needed to help carry out this work.

Note. All vehicles with DSC without precharging pumps must be filled with the new DOT4 low-viscosity brake fluid. All other models can be filled with the same brake fluid.

1. Connect BMW Diagnosis and Information System (DIS).
2. Using DIS, call up service function BLEEDING ABS/DSC3 HYDRAULICS.
3. Connect bleeding unit to expansion tank and switch on.
4. Flush entire braking system. Connect bleeder hose with container to bleed valve on rear right brake caliper. Open bleed valve and flush until clear, bubble-free brake fluid emerges. Close bleeder valve. Follow same procedure on rear left, front right and front left in that order.
5. Bleed front or rear axle brake circuit. Connect bleeder hose with container to bleed valve on right brake caliper. Open bleed valve. Run bleeding routine with BMW Diagnosis and Information System (DIS) with bleeder valve open. After running routine, press brake pedal 5 times to stop. Clear, bubble-free brake fluid must flow out. Close bleeder valve. Repeat procedure at left caliper.
6. Switch off bleeder unit and disconnect from expansion tank.
7. Check brake fluid level.
8. Close expansion tank. Take care of rubber gasket in lid.

Inspection

When first ratchet is engaged, no braking force should be exerted. The difference in wheel circumferential forces between the left and right wheels may deviate by a maximum of 30 percent from the greater value (measured on brake analyzer). The parking brake must be readjusted in the event of greater deviations in the wheel circumferential force. It must be possible to brake with locked wheels with the parking brake. The parking brake must be readjusted whenever the actuation stroke is greater than 10 teeth.

Parking Brake Shoes

Note. Accurate adjustment of the parking brake is only possible if Bowden cables and all moving parts move easily and function correctly. See PARKING BRAKE BOWDEN CABLE SETTING PROCEDURE .

Note. Numbers in text refer to numbers in figures.

Scheme 1

Scheme 2

Scheme 3

Scheme 4

1. Unclip parking brake lever trim (1) at rear and tilt forward. Lock adjuster unit (ASZE). Using Special Tool (32 10 30), press stop (2) of adjusting spring back to such an extent that retaining hook (3) engages in stop (2). (Scheme 1)
2. Raise vehicle and support safely. Completely unscrew one wheel stud on each rear wheel. Turn wheel until adjustment screw is visible in tapped hole. (Scheme 2)
3. Turn adjusting screw with a screwdriver until the wheel is no longer able to turn. (Scheme 3) Then unfasten the adjusting screw 8 notches. Unlock adjuster unit (ASZE). Lever restraint hook (2) outward with a screwdriver (1). Restraint hook (2) must disengage from stop of adjusting spring. (Scheme 4)

Parking Brake Bowden Cable Setting Procedure

Note. Parking brake lever must be applied 5 times to about 295 lbs. (400 N) actuating force.

1. Using brake analyzer, with parking brake released, shift transmission into neutral. Without locking differential 110 lbs. (150 N) or less. With locking differential 148 lbs. (200 N) or less (possibly odd display).
2. With parking brake on first tooth, there is no increase in braking force. Indicator light may be lit.
3. With parking brake on second tooth, an increase in braking force must take place. Indicator light must be lit.
4. With parking brake on third tooth, an increase in braking force must take place.
5. With parking brake on fifth tooth, braking force display must have reached 295 lbs. (400 N) or more.

Parking Brake Breaking In Procedure

Note. Break-in procedure is applicable in case of insufficient braking effect or after replacing brake discs and/or brake shoes.

1. Using brake analyzer, apply parking brake lever until wheel circumferential force on first wheel is 590 lbs. (800 N).
2. Lock lever in next lower tooth. Release parking brake after 2 minutes.

Parking Brake Breaking In Procedure While Driving

1. Drive car to 25 MPH and apply parking brake lever until braking action can be felt.
2. Pull up parking brake lever into next notch and drive for about .3 mile.
3. Release parking brake and allow brake to cool down. Repeat procedure, if necessary.

TROUBLESHOOTING

Brake performance is mainly affected by 3 things: level and condition of brake fluid, brake system's ability to create and maintain hydraulic pressure, and condition of friction components. Tires and wheels are important parts of the braking system. Check tires for wear, flat spots, trueness and proper inflation. Visually check the hydraulic system starting at the master cylinder. Check all brake fluid lines and couplings for leaks, kinks, chafing and corrosion.

On vehicles with vacuum brake booster, check brake booster by pumping brake pedal approximately 10 times with engine off. Then hold down brake pedal and start engine. Pedal should fall slightly. If not, check for any visible faults before suspecting a faulty brake booster. Check for strong vacuum at vacuum hose fitting on booster. Ensure vacuum check valve has one-way flow. For trouble shooting symptoms, see SYMPTOM INDEX table.

SYMPTOM INDEX

SYMPTOM A: BRAKES PULL TO ONE SIDE

SYMPTOM A: BRAKES PULL TO ONE SIDE

SYMPTOM B: BRAKES EXCESSIVELY HOT WHILE DRIVING

SYMPTOM B: BRAKES EXCESSIVELY HOT WHILE DRIVING

SYMPTOM C: POOR BRAKING EFFECT

SYMPTOM C: POOR BRAKING EFFECT

SYMPTOM D: BRAKE PEDAL MOTION TOO SOFT & SPONGY

SYMPTOM D: BRAKE PEDAL MOTION TOO SOFT & SPONGY

SYMPTOM E: BRAKE PEDAL TRAVEL EXCESSIVE

SYMPTOM E: BRAKE PEDAL TRAVEL EXCESSIVE

SYMPTOM F: UNEVEN PAD WEAR

SYMPTOM F: UNEVEN PAD WEAR

SYMPTOM G: BRAKE PADS WORN AT ANGLE

SYMPTOM G: BRAKE PADS WORN AT ANGLE

SYMPTOM H: SEIZED BRAKE PADS

SYMPTOM H: SEIZED BRAKE PADS

SYMPTOM I: BRAKES SQUEAL OR RATTLE

SYMPTOM I: BRAKES SQUEAL OR RATTLE

SYMPTOM J: BRAKE PEDAL DEAD TRAVEL EXCESSIVE

SYMPTOM J: BRAKE PEDAL DEAD TRAVEL EXCESSIVE

SYMPTOM K: JAMMED PISTON IN BRAKE CALIPER

SYMPTOM K: JAMMED PISTON IN BRAKE CALIPER

SYMPTOM L: PULSATING EFFECT ON BRAKE PEDAL

SYMPTOM L: PULSATING EFFECT ON BRAKE PEDAL

SYMPTOM M: PARKING BRAKE EFFECT INSUFFICIENT

SYMPTOM M: PARKING BRAKE EFFECT INSUFFICIENT

BRAKE PAD WARNING LIGHT

Note. Yellow brake pad warning light is located in instrument cluster. Light will come on when brake pad thickness sensor wears through and grounds itself by contacting brake rotor. After replacement of brake pad thickness sensor, light should go out immediately or after several key-starts.

BRAKE WARNING LIGHT

Brake warning light is located in instrument cluster. Turn ignition on and release parking brake. Verify light is off. Remove master cylinder filler cap. Warning light should come on. If warning light does not come on, check bulb and circuit connections.

BRAKE BOOSTER

Note. The leakage (high/low pressure test) must be carried out with engine switched off.

Low Pressure Test

Detach hose from connection piece. Install Vacuum Tester (34 3 100) between connection piece and vacuum hose of non-return valve. (Scheme 5) Start engine. Check buildup of partial vacuum. Switch off engine. Press the brake pedal to set a vacuum pressure of not more than 11.6 psi (0.8 bar) and wait for the value to stabilize. When the brake pedal is not pressed, the vacuum pressure is permitted to drop over a test period of one minute by a maximum of.87 psi (0.06 bar). If specified values are not reached

Scheme 5

1. Check line connections for vacuum seal.
2. Replace vacuum non-return valve.
3. Check seal between brake booster and brake master cylinder (sealing ring) for perfect condition and correct seating.
4. If specified values are not achieved when test is repeated, replace brake booster. See «BRAKE BOOSTER»(/bmw/z4/e85e86-2002-2005/remont/mechanical-hydraulic/#brakes-repair) under REMOVAL & INSTALLATION.

BRAKE SYSTEM

Note. High-pressure and low-pressure tests (leakage test) must be performed with engine off.

High-Pressure Test

Note. Perform test on both brake circuits, front and rear.

1. Unscrew bleeder screw, connect pressure tester and bleed. (Scheme 6)
2. Load brake pedal with a force of approximately 112 lbs. (500 N), and block pedal with pedal support.
3. After 2 minutes, pressure must not drop by more than 8 percent.
4. Perform low-pressure test. See «LOW PRESSURE TEST»(/bmw/z4/e85e86-2002-2005/remont/mechanical-hydraulic/#brakes-repair).

Note. Perform test on both brake circuits, front and rear.

1. Unscrew bleeder screw, connect pressure tester and bleed. (Scheme 6)
2. Load brake pedal with a force of 30-72 psi (2-5 bar), and block pedal with pedal support. Car and measuring equipment must remain perfectly still as vibrations will distort result.
3. Pressure should remain constant during five minute test.
4. Check all rubber parts in case of excessive pressure drop.
5. Bleed brake calipers and wheel brake cylinders after finishing test. See «BLEEDING BRAKE SYSTEM»(/bmw/z4/e85e86-2002-2005/remont/mechanical-hydraulic/#brakes-repair).

Scheme 6

BRAKE PAD THICKNESS

Note. The thickness of outer brake pads can be determined without removing wheels.

Note. Numbers in text refer to numbers in figures.

1. If necessary, move car until opening for brake pad wear indicator can be seen through rim styling.
2. Insert Special Tool (34 1 260) through rim into opening for brake pad wear indicator.
3. Press special tool onto brake pad. Slide ring (1) in direction of arrow as far as it will go and read off measured value. (Scheme 7)
4. Minimum thickness for all models is stamped in brake disc shell. Wear warning from residual brake pad thickness is.11" (3 mm). Maximum machining limit per friction ring side is.031" (.8 mm). For minimum thickness see «BRAKE PAD MINIMUM THICKNESS»(/bmw/z4/e85e86-2002-2005/remont/mechanical-hydraulic/#brakes-repair) table.

BRAKE PAD MINIMUM THICKNESS

Scheme 7

Note. Numbers in text refer to numbers in figures.

Removal & Installation

1. Remove master cylinder. See «MASTER CYLINDER»(/bmw/z4/e85e86-2002-2005/remont/mechanical-hydraulic/#brakes-repair__master-cylinder).
2. Remove brake pedal.
3. Remove vacuum hose for brake booster. See «BRAKE BOOSTER VACUUM HOSE»(/bmw/z4/e85e86-2002-2005/remont/mechanical-hydraulic/#brakes-repair__brake-booster-vacuum-hose).
4. On 3.0L, remove exhaust sound generator. On all models, remove nuts (1). (Scheme 8) Carefully remove brake unit (1) from bulkhead and tilt out in direction of engine. (Scheme 9)
5. Do not use any force when removing or installing booster. Remove brake unit vertically upward out of equipment compartment. To install, reverse removal procedure. Replace self-locking nuts. Tighten to specification. See «TORQUE SPECIFICATIONS»(/bmw/z4/e85e86-2002-2005/remont/mechanical-hydraulic/#brakes-repair__torque-specifications).

Scheme 8

Scheme 9

BRAKE BOOSTER NON-RETURN VALVE

Note. Numbers in text refer to numbers in figures.

1. Actuate brake pedal several times to reduce vacuum in brake booster, making it easier to pull off vacuum hose.
2. Open hose clips (1, 2) and pull off vacuum hoses. (Scheme 10)
3. Pull off rubber seal (1). (Scheme 11)
4. Unfasten catches (4 pieces), and pull upper section of separating wall seal upward and off.
5. Pull non-return valve with rubber gasket upward out of lower section of separating wall seal.
6. To install, reverse removal procedure. Ensure that rubber gasket is correctly seated and retaining hooks are properly locked.

Scheme 10

Scheme 11

BRAKE BOOSTER VACUUM HOSE

Note. Numbers in text refer to numbers in illustrations.

Scheme 12

1. Before beginning work, fully press the brake pedal several times to reduce the vacuum pressure in the brake booster. This makes it easier to detach the vacuum hose. The non-return valve and the molded hose are permanently connected to each other and are replaced as a single unit. Pull non-return valve (1) out of brake booster. Open hose clip (2). Pull off vacuum hose (3). (Scheme 12)
2. To install, reverse removal procedure. Check seal for non-return valve and replace if necessary. Replace hose clamp (2).

BRAKE DISC

Note. Numbers in text refer to numbers in figures.

Removal & Installation (Front)

1. Raise and support vehicle. Remove wheel(s).
2. If necessary, remove and clean disc pads. See «DISC PADS»(/bmw/z4/e85e86-2002-2005/remont/mechanical-hydraulic/#brakes-repair__disc-pads).
3. Remove caliper mounting bolts (1) and raise caliper off mounting assembly and suspend from vehicle with wire. (Scheme 13) Brake hose remains connected.
4. Remove bolts and take off brake disc. (Scheme 14) Do not under any circumstances strike friction ring with a hammer or similar object. If necessary, carefully tap on base of brake disc chamber with a rubber mallet.
5. To install, reverse removal procedure. Replace brake disc retaining screw. Thoroughly clean contact surface of wheel hub, remove traces of corrosion if necessary. Unevenness on contact surface may result in distortion of brake disc. Inboard vented brake disks are balanced. Never remove or reposition balance clips. (Scheme 15)

Scheme 13

Scheme 14

Scheme 15

Removal & Installation (Rear)

Remove wheels. Remove bolts (1). (Scheme 16) Remove and suspend brake caliper from vehicle. Leave brake hose connected. Unscrew bolts and take off brake disc. To install, reverse removal procedure. Replace brake disc retaining screw. (Scheme 17) Adjust parking brake. See PARKING BRAKE under ADJUSTMENTS.

Scheme 16

Scheme 17

BRAKE EXPANSION TANK

Note. Numbers in text apply to numbers in figures.

Scheme 18

Scheme 19

1. Suck brake fluid out of expansion tank with a suction device used exclusively for drawing off brake fluid.
2. Disconnect electrical connector (1). If necessary, detach supply hoses (1) of clutch hydraulics and precharging pump. Remove retaining screw (3). (Scheme 18)
3. Pull off expansion tank from master brake cylinder. (Scheme 19) Feed hoses must be secured in vertical position so that no fluid can escape.
4. Check rubber plug in master brake cylinder for damage. Replace as necessary.
5. To install, reverse removal procedure. Tighten bolts to specification. See «TORQUE SPECIFICATIONS»(/bmw/z4/e85e86-2002-2005/remont/mechanical-hydraulic/#brakes-repair__torque-specifications). Push expansion tank vertically onto master brake cylinder.
6. Connect hoses, fill expansion tank, and bleed system. See «BLEEDING BRAKE SYSTEM»(/bmw/z4/e85e86-2002-2005/remont/mechanical-hydraulic/#brakes-repair).

BRAKE HOSES

Note. Numbers in text refer to numbers in illustration.

Scheme 20

1. Apply pedal prop and depress brake pedal slightly. This prevents brake fluid from emerging from the expansion tank when the brake lines are opened. Pull brake hose out of holder (1). Disconnect brake hose from brake line (2). Grip brake hose at square (3) to prevent connecting piece from turning in retaining bracket. Detach brake hose from brake caliper (4). (Scheme 20)
2. To install, reverse removal procedure. First tighten brake hose on brake caliper. Move wheels into straight-ahead position. Insert brake hose in bracket and screw onto brake pipe. Never twist brake hose when installing it and avoid all contact with parts attached rigidly to the body. See «TORQUE SPECIFICATIONS»(/bmw/z4/e85e86-2002-2005/remont/mechanical-hydraulic/#brakes-repair__torque-specifications). After installation, bleed brake system. See «BLEEDING BRAKE SYSTEM»(/bmw/z4/e85e86-2002-2005/remont/mechanical-hydraulic/#brakes-repair).

Scheme 21

1. Apply pedal prop and depress brake pedal slightly. This prevents brake fluid from emerging from the expansion tank and air from entering the system when the brake lines are opened. Release union nut (1) by gripping brake hose at square (2). Disconnect brake hose from brake caliper (3). (Scheme 21)
2. To install, reverse removal procedure. Mount and tighten brake hose on brake caliper first, then on brake line/brake hose point of connection. See «TORQUE SPECIFICATIONS»(/bmw/z4/e85e86-2002-2005/remont/mechanical-hydraulic/#brakes-repair__torque-specifications). After installation, bleed brake system. See «BLEEDING BRAKE SYSTEM»(/bmw/z4/e85e86-2002-2005/remont/mechanical-hydraulic/#brakes-repair).

BRAKE LINES

1. Apply pedal prop and depress brake pedal slightly. This prevents brake fluid from flowing out of expansion tank and into brake system when brake lines are opened.
2. Suck brake fluid out of expansion tank with a suction device used exclusively for drawing off brake fluid.
3. Ensure that square head screw on brake hose does not rotate in metal bracket. If necessary, brace brake hose with mold grips. Unfasten brake hose from brake caliper.
4. Brake pipes are only supplied straight, in correct length and fitted with connecting nipples. Bend new pipe as required using Bending Tool (34 51 00). Removed pipe can be used as template.
5. If replacing front brake pipe, move wheels into straight-ahead position. Install new pipe and tighten to specification. See «TORQUE SPECIFICATIONS»(/bmw/z4/e85e86-2002-2005/remont/mechanical-hydraulic/#brakes-repair__torque-specifications) .
6. Remove pedal prop and bleed brake system. See «BLEEDING BRAKE SYSTEM»(/bmw/z4/e85e86-2002-2005/remont/mechanical-hydraulic/#brakes-repair) .

CALIPER ASSEMBLY

Note. When forcing piston back, observe brake fluid level in supply tank. Overflowing brake fluid will damage paint.

Note. Numbers in text refer to numbers in figures.

Scheme 22

1. Raise and support vehicle. Remove wheel(s). Apply pedal prop and depress brake pedal slightly. This prevents brake fluid from emerging from the expansion tank and air from entering the brake system after the brake lines have been detached. Disconnect brake pipe from connection with brake hose.
2. On left side, disconnect wear indicator. Remove brake caliper screws (1). (Scheme 22) Remove brake caliper.
3. To install, reverse removal procedure. Bleed hydraulic system. See «BLEEDING BRAKE SYSTEM»(/bmw/z4/e85e86-2002-2005/remont/mechanical-hydraulic/#brakes-repair). Tighten caliper mounting bolts to specification. Install and tighten wheel bolt. See «TORQUE SPECIFICATIONS»(/bmw/z4/e85e86-2002-2005/remont/mechanical-hydraulic/#brakes-repair__torque-specifications).

Scheme 23

1. Raise and support vehicle. Remove wheel(s). Apply pedal prop and depress brake pedal slightly. This prevents brake fluid from emerging from the expansion tank and air from entering the brake system after the brake lines have been detached.
2. Remove caliper screws (1). Disconnect brake hose (2). (Scheme 23) Unfasten brake hose on connection point to brake line. On right side, disconnect plug connection for brake pad lining sensor. Pull off caliper toward rear of vehicle.
3. To install, reverse removal procedure. Install brake hose without torsional stress. First tighten the brake hose on the brake cover, then tighten connection on brake line to specification. See «TORQUE SPECIFICATIONS»(/bmw/z4/e85e86-2002-2005/remont/mechanical-hydraulic/#brakes-repair__torque-specifications). Check routing and securing of brake pad wear indicator cable. Check for correct securing with tab of dust cap. It is absolutely essential to prevent the cable on the rim from being scuffed.

DISC PADS

Note. Numbers in text refer to numbers in figures.

Scheme 24

Scheme 25

Scheme 26

Scheme 27

Scheme 28

Scheme 29

Scheme 30

Scheme 31

1. Raise and support vehicle. Remove wheel(s). Lift out retaining spring (1). (Scheme 24) Disconnect plug connection for brake pad lining wear sensor. Remove plastic plugs (1). (Scheme 25) Remove guide screws (1) and lift out brake caliper toward rear of vehicle. (Scheme 22) Do not allow brake caliper to hang from brake hose. Retract piston fully back with Special Tool (34 10 50). (Scheme 26) When turning back the piston, watch the brake fluid level in the expansion tank, as overflowing brake fluid can destroy the paint.
2. Remove outer brake pad. (Scheme 27) Inner brake pad is located with its spring in the piston. In the event of one-sided brake pad wear, do not change brake pads around. New brake pads may only be installed if the brake disc thickness is greater than or equal to the minimum brake disk thickness. See «BRAKES - TECHNICAL DATA»(/bmw/z4/e85e86-2002-2005/remont/mechanical-hydraulic/#brakes-technical-data). Observe minimum thickness of brake pads. Clean brake pads. Do not grease backs of brake pads sleeve. Check dust sleeve (1) for damage and replace if necessary. (Scheme 28)
3. To install, reverse removal procedure. See «TORQUE SPECIFICATIONS»(/bmw/z4/e85e86-2002-2005/remont/mechanical-hydraulic/#brakes-repair__torque-specifications). Clean contact face (2) of brake piston and apply a thin coating of anti-squeak compound. (Scheme 28) Dust sleeve must not come into contact with anti-squeak compound as this may cause dust sleeve to swell. Clean contact faces (1, 2) of brake pad hammer heads/brake caliper housing and coat with anti-squeak compound. (Scheme 29) Clean contact face (3) of brake caliper and apply a thin coating of anti-squeak compound. (Scheme 30) Clean contact face of brake caliper mounting bracket and apply a thin coating of anti-squeak compound. (Scheme 31) Reassemble caliper assembly. See «CALIPER ASSEMBLY»(/bmw/z4/e85e86-2002-2005/remont/mechanical-hydraulic/#brakes-repair__caliper-assembly). After installation, press brake pedal several times to the floor so that brake pads contact brake discs. When installing new brake pads on front and rear axles, check brake fluid level. Top up to MAX mark as necessary.

Remove wheels. Remove cover plug (1). (Scheme 32) On right side, disconnect plug connection for brake pad wear sensor. Inspect sensor and replace as necessary. On both sides, remove caliper guide screws (2). (Scheme 33) Lift out retaining spring (3). (Scheme 34) Withdraw brake caliper backward. Turn piston fully back with Special Tool (34 10 50). (Scheme 26) When turning back the piston, watch the brake fluid level in the expansion tank, as overflowing brake fluid can destroy the paint. Remove brake pads. Inner brake pad is located with its spring in the piston. (Scheme 27)

Scheme 32

Scheme 33

Scheme 34

1. New brake pads may only be installed if the brake disk thickness is greater than or equal to the minimum brake disk thickness. Observe minimum thickness of brake pads. Clean brake pads. Do not grease back of brake pad sleeve. Check dust sleeve (1) for damage and replace as necessary. Clean contact face (2) of brake piston and apply a thin coating of anti-squek compound. (Scheme 28)
2. Clean contact faces (1, 2) of brake pad hammer heads/brake caliper housing and coat with anti-squeak compound. (Scheme 29) Clean contact face (3) of brake caliper and apply a thin coating of anti-squeak compound. (Scheme 30) Clean brake caliper mounting bracket at hammer head guides and apply a thin coating of anti-squeak compound. (Scheme 31) Check caliper guide screw threads. Replace all guide screws that are not in perfect condition. Reassemble caliper. See «CALIPER ASSEMBLY»(/bmw/z4/e85e86-2002-2005/remont/mechanical-hydraulic/#brakes-repair__caliper-assembly).

MASTER CYLINDER

Note. Numbers in text refer to numbers in figures.

Scheme 35

1. Suck brake fluid out of expansion tank with a suction device used exclusively for drawing off brake fluid.
2. Remove brake fluid expansion tank. See «BRAKE EXPANSION TANK»(/bmw/z4/e85e86-2002-2005/remont/mechanical-hydraulic/#brakes-repair__brake-expansion-tank). Remove Dynamic Stability Control (DSC) pressure sensors "H" and "V". See «PRESSURE SENSOR "H"»(/bmw/z4/e85e86-2002-2005/remont/mechanical-hydraulic/#brakes-repair__pressure-sensor-h) and «PRESSURE SENSOR "V"»(/bmw/z4/e85e86-2002-2005/remont/mechanical-hydraulic/#brakes-repair__pressure-sensor-v).
3. Disconnect all hydraulic lines from master cylinder (1). Close off brake lines and master brake cylinder using appropriate seal plugs.
4. Remove hex nuts (2). Remove brake master cylinder (3) from brake booster (4). (Scheme 35)

Scheme 36

Scheme 37

1. Replace "O" ring. (Scheme 36) Install master brake cylinder to brake unit. When inserting the brake master cylinder (2) into the brake booster (1), make sure the pressure rod of the brake booster (1) and that of the brake master cylinder (2) are on one level. Replace self-locking nuts and tighten to specification. (Scheme 37) See «TORQUE SPECIFICATIONS»(/bmw/z4/e85e86-2002-2005/remont/mechanical-hydraulic/#brakes-repair__torque-specifications).
2. Attach and tighten screw connections of brake lines and tighten to specification. See «TORQUE SPECIFICATIONS»(/bmw/z4/e85e86-2002-2005/remont/mechanical-hydraulic/#brakes-repair__torque-specifications).
3. Push expansion tank vertically onto master brake cylinder.
4. Refill brake fluid and bleed system. See «BLEEDING BRAKE SYSTEM»(/bmw/z4/e85e86-2002-2005/remont/mechanical-hydraulic/#brakes-repair).

PARKING BRAKE LEVER & MOUNTING PAN

Note. Numbers in text refer to number in figures.

Note. Parking brake handle must be protected against damage when mounting pan is fed out downward. Parking brake handle must also be replaced when the adjuster unit (ASZE) is replaced.

Scheme 38

Scheme 39

Scheme 40

Scheme 41

Scheme 42

Scheme 43

Scheme 44

1. Remove propeller shaft. Remove parking brake lever trim. Lock adjuster unit (ASZE). Using Special Tool (32 10 30), press stop (1) of adjusting spring back until restraining hook (2) snaps into place in stop (1). (Scheme 38) Remove one wheel stud. Bring wheel into position (tapped hole turned down approximately 20 degrees from horizontal). (Scheme 39) Nipple (1) and expander lock (2) are visible through tapped hole. (Scheme 40)
2. Push in core of parking brake cable in direction of expander lock as far as it will go and grip firmly. Press nipple (1) downward through tapped hole with a screwdriver. Unclip parking brake cables from fixture (1). (Scheme 41) Release screws (2) and lower mounting pan a little. Press retaining lug (1) downward and pull out cable (2). (Scheme 42) Feed out mounting pan toward bottom. Pull parking brake cables out of rear axle guide. Unclip mounting clip (1) upward out of balance arm (2). (Scheme 43) Feed parking brake cables (1) inward with a screwdriver and pull out of balance arm (2). (Scheme 44)
3. To install, reverse removal procedure. Reinstall wheel stud only after parking brake has been adjusted. Insert parking brake cable in brake carrier/brake guard plate. Sleeve must be inserted up to stop. Nipple of parking brake cable must audibly snap into place in expander lock. Replace self-locking nuts. Replace seal (3).

Note. Numbers in text refer to numbers in figures.

Scheme 45

Scheme 46

Scheme 47

1. Raise and support vehicle. Remove rear wheel(s).
2. Remove rear brake disc. See «BRAKE DISC»(/bmw/z4/e85e86-2002-2005/remont/mechanical-hydraulic/#brakes-repair__brake-disc).
3. Unclip parking brake lever trim (1) at rear and tilt forward. Lock Adjuster Unit (ASZE). Use Special Tool (32 10 30) to press back the stop (2) of the adjusting spring until the restraining hook (3) snaps into place in the stop (2). (Scheme 45)
4. Disconnect return spring on each side (1) with brake spring pliers. (Scheme 46) Turn clamping pins (1) with Special Tool (34 40 00) through 90 degrees and disconnect. Remove brake shoes (2). (Scheme 47)
5. To install, reverse removal procedure. Check return spring (1) and replace as necessary. Pay attention to installation position of adjustment screw (2). (Scheme 46) Apply a thin coat of grease to bushing and screw threads. Adjust parking brake and check operation. See «PARKING BRAKE»(/bmw/z4/e85e86-2002-2005/remont/mechanical-hydraulic/#brakes-repair) under ADJUSTMENTS.

PARKING BRAKE SHOES EXPANDER LOCK

Note. Numbers in text refer to numbers in figures.

Remove parking brake shoes. See PARKING BRAKE SHOES. Unclip parking brake lever trim (1) at rear and tilt forward. Lock adjuster unit (ASZE). Use Special Tool (32 10 30) to press back stop (2) of adjusting spring until restraining hook (3) snaps into place in stop (2). (Scheme 45) Pull expander lock (1) forward. Disconnect parking brake cable (2) and remove expander lock. (Scheme 48) To install, reverse removal procedure.

Scheme 48

PRESSURE SENSOR "H"

Note. Numbers in text refer to numbers in illustration.

1. Apply pedal prop and depress brake pedal slightly. This prevents brake fluid from emerging from the expansion tank and air from entering the brake system after the brake lines have been detached. Disconnect brake pipe from connection with brake hose.
2. Unfasten plug connection (1). Detach pressure sensor (2) from master brake cylinder (3). (Scheme 49) After replacing the pressure sensor, carry out an adjustment with Diagnosis and Information System (DIS) under menu item SERVICE FUNCTIONS. To install, reverse removal procedure. After installation, bleed brake system.

Scheme 49

PRESSURE SENSOR "V"

Note. Numbers in text refer to numbers in illustration.

Scheme 50

Scheme 51

1. Apply pedal prop and depress brake pedal slightly. This prevents brake fluid from emerging from the expansion tank and air from entering the brake system after the brake lines have been detached. Disconnect brake pipe from connection with brake hose.
2. Release and remove pipe (1) from hydraulic unit (2) and from brake master cylinder (3). Unfasten plug connection (1). Detach pressure sensor (2) from brake master cylinder. (Scheme 50)and (Scheme 51). After replacing the pressure sensor, carry out an adjustment with Diagnosis and Information System (DIS) under menu item SERVICE FUNCTIONS. To install, reverse removal procedure. After completing tasks, bleed brake system. See «TORQUE SPECIFICATIONS»(/bmw/z4/e85e86-2002-2005/remont/mechanical-hydraulic/#brakes-repair__torque-specifications).

See WHEEL BEARINGS under REMOVAL & INSTALLATION in SUSPENSION - REAR article.

BRAKE CALIPER

Note. Numbers in text refer to numbers in figures.

Disassembly

1. Remove caliper. See «CALIPER ASSEMBLY»(/bmw/z4/e85e86-2002-2005/remont/mechanical-hydraulic/#brakes-repair__caliper-assembly).
2. Take off plastic caps (1). Unscrew caliper guide screws (2). (Scheme 22) Dismantle brake caliper and remove brake pads. Carefully force piston out through connection bore with compressed air. To protect piston, place a protective plate (hard wood or hard felt) in caliper recess. (Scheme 52) Do not grip piston with fingers. Check guide sleeves (5), fitting repair kit guide sleeve if necessary. (Scheme 53) Remove sealing ring carefully with a plastic needle. (Scheme 54)

Scheme 52

Scheme 53

Scheme 54

Cleaning & Inspection

Clean components in alcohol and dry with compressed air. Inspect caliper bore and pistons for wear or damage. Replace caliper assembly if cylinder bore is corroded or worn. Do not hone.

Scheme 55

Scheme 56

Scheme 57

1. Coat cylinder bore, piston, dust sleeve and sealing ring with a light coat of brake cylinder paste.
2. Install sealing cover in rear annular groove of cylinder bore. (Scheme 55)
3. Install dust sleeve in front annular groove and press into annular groove over entire diameter. (Scheme 56) The area between the dust sleeve and the brake caliper housing must be kept dry. It must not come into contact with brake cylinder paste or brake fluid so as to ensure that the dust sleeve is perfectly seated.
4. Take up brake piston with an extension and socket and gently press onto dust sleeve. Apply compressor air into sleeve (maximum 3 bar). (Scheme 57) Coat dust sleeve and brake piston with brake fluid to facilitate installation of dust sleeve.
5. Only clean guide screws, do not grease. Check and replace if necessary. Tighten to specification. See «TORQUE SPECIFICATIONS»(/bmw/z4/e85e86-2002-2005/remont/mechanical-hydraulic/#brakes-repair__torque-specifications).
6. Install caliper. See «CALIPER ASSEMBLY»(/bmw/z4/e85e86-2002-2005/remont/mechanical-hydraulic/#brakes-repair__caliper-assembly).

Always fine-grind both sides of both brake disks on one axle. Observe maximum machining dimension per friction ring side, minimum brake disk thickness and surface roughness of brake surfaces. Only one brake pad set may be used up on brake discs which have been lathe-turned to minimum thickness.

SPECIFICATIONS

Note. See BRAKES - TECHNICAL DATA .

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

See also:
• BRAKES - TECHNICAL DATA
• WHEEL BEARINGS
• BASIC BLEEDING PROCEDURES
• PARKING BRAKE BOWDEN CABLE SETTING PROCEDURE
• SYMPTOM INDEX
• A
• B
• C
• D
• E
• F
• G
• H
• I
• J
• K
• L
• M
• MASTER CYLINDER
• BRAKE BOOSTER VACUUM HOSE
• TORQUE SPECIFICATIONS
• DISC PADS
• CALIPER ASSEMBLY
• BRAKE EXPANSION TANK
• PRESSURE SENSOR "H"
• PRESSURE SENSOR "V"
• BRAKE DISC