Bosch Alternators 1974

Car Manufacturers Covered:

• Alfa Romeo
• Audi
• BMW
• Capri
• Fiat 128 & X1/9
• Mercedes-Benz
• Opel
• Porsche
• Saab
• Volkswagen
• Volvo 4 Cylinder

CHANGES, CAUTIONS, CORRECTIONS

BATTERY INSTALLATION, BATTERY CHARGING, OR USING A BOOSTER BATTERY TO START ENGINE - Reversed polarity or excessive voltage will result in damage to alternator system. Note the following to prevent damage:

Battery Installation - Negative battery terminal must be connected to ground. Positive terminal must be connected to starter lead. DO NOT reverse battery leads.

Battery Charging - If a Quick Charger is used, both battery cables must be disconnected from the battery. DO NOT use a Quick Charger to provide starting voltage.

Booster Battery (For Engine Start) - Booster battery must be connected with negative lead to negative terminal of battery and positive lead to positive terminal of battery. DO NOT reverse battery leads.

                                   APPLICATIONS

Model                             Type No.                          Part No.

Alfa Romeo ................ K1 14V 45A 22 ............. * 0 120 400 848

Audi .................................. ... ............................. ** 059 903 017D

BMW

     2002, 2002A .......... K1 14V 45A 22 ............. * 0 120 400 752

     2002 tii ................... K1 14V 45A 22 ............. * 0 120 400 794

     3.0 .......................... K1 14V 45A 20 ............. * 0 120 400 702

Capri

     4 Cyl. W/A.C ............... ... .............................. *** D4RY-C

     4 Cyl. All Others ......... ... .............................. *** D4RY-B

     V6 W/ A.C. .................. ... .............................. *** D4RY - D

     V6 All Others .............. ... .............................. ***D4RY-A

Fiat 128 & X1/9 ................ ... ............................. * 0120 300 568

Mercedes Benz

     230, 240D .................... ... .............................. **** 0041 546 902

     280 ........................ K1 14V 55A 20 .............. **** 0041 541 802

     450 ........................ K1 14V 55A 20 .............. **** 0031 545 602

Opel ................................ ... ................................ * 0 120 400 620

Porsche

     4 Cyl .......................... ... ................................ ***** 022 903 023

     6 Cyl .......................... ... ................................ *****911 603 118 00

Saab

     99 .............................. ... ................................. *0120 400 850

     V4 ............................. ... .................................  *0120 400 657

Volkswagen 

     Type 1 ........................ ... ................................ * 0120 400 836 or 862

     Type 2 & 4 ................. ... ................................ * 0120 400 721

     Dasher ........................ ... ................................ * 0120 489 532 or 535

Volvo 

     140 ............................. ... ................................ * 0120 400 756

     164 ............................. ... ................................ * 0190 601 011

* - Bosch Part No.

** - Audi Part No.

*** - Motorcraft Part No.

**** - Mercedes Benz Part No. 

***** - VW Part No.

DESCRIPTION

Bosche alternators are conventional three-phase, self-rectifying type alternators. Nine rectifier diodes are connected to the stator windings (three to each phase lead). The diodes change the alternator A.C. voltages to D.C. voltages coming out of the "B+" and "D+" terminals of the alternator.

                                  SPECIFICATIONS

Alternator*                     Amp Output @ RPM                     Max Current

G1 14V 33A 27 ...................  33 @ 5000 ................................... 40A

K1 14V 35A 20 ................... 23 @ 2000 .................................... 35A

K1 14V 45A 20 .................... 30 @ 2000 ................................... 45A

K1 14V 45A 20 .................... 30 @ 2200 ................................... 45A

K1 14V 50A 20 .................... 33 @ 2000 ................................... 50A

K1 14V 55A 20 .................... 36 @ 2000 ................................... 55A

K1 14V 55A 22 .................... 36 @ 2200 ................................... 55A

* - Charging voltage: 14.

Field Coil Resistance - 4.0 ohms + 10% measured at slip rings at normal ambient temperature.

Stator Windings Resistance - .2 ohms + 10% measured between the phase output terminals

ON VEHICLE TESTING

NOTE - Off vehicle testing is explained as part of Overhaul procedure in this article.

WIRING CONTINUITY TEST

Disconnect terminal plug from rear of alternator and connect a voltmeter negative terminal to ground. With Ignition "ON", connect positive lead to each of  the connector wires, in turn. Voltmeter should read battery voltage as each positive connection is made. If proper voltage is not read, trace each wire to find fault.

VOLTAGE DROP TEST - GROUND SIDE

Connect voltmeter between negative terminal of battery and alternator housing. Start engine and run at approximately 3000 RPM. If voltmeter reading exceeds .25 Volts, a high resistance in negatvie side of charging circuit is indicated. If so, check for loose, dirty, or corroded connections.

OUTPUT TEST

Disconnect terminal plug from rear of alternator and connect ammeter, in series between alternator center terminal and corresponding socket in terminal plug. Also connect a jumper lead between the "D+" terminal and its corresponding socket in terminal plug. Start engine and run at approximately 3000 RPM. Turn on headlights and leave on for five minutes. Ammeter should read maximum alternator amperage at normal operating temeperature.

REGULATOR CONTROL VOLTAGE TEST

Connect a voltmeter between main terminals of battery. Connect an ammeter, in series, between "B+" terminal of alternator and corresponding terminal of connector plug. Connect a jumper lead between alternator "D+" terminal and corresponding terminal of connector plug. Start engine and increase speed to approximately 3000 RPM. Run engine until charging rate falls below 10 amps. The voltmeter should then read 14.1 - 14.4 Volts. If these readings are not obtained, replace regulator.

NOTE - The test cables should not be removed or the load excessively reduced during the diodes. The control lamp should not go on at any time during the test.

BOSCH ALTERNATOR (TYPICAL)

OVERHAUL

DISASSEMBLY

NOTE - On 0 120 400 600 series alternators, lift carbon brushes with hook and secure them, prior to disassembly (see illustrations).

1) Remove nut, pulley, hub and key. Mark location of alternator in blower housing. Unscrew brush

LIFTING CARBON BRUSHES
(0 120 400 600 Series)

plate assembly and remove from alternator. Remove bolts from end frame, then remove frame and field rotor. Press rotor out of end frame. Press ball bearing off rotor. Remove insulating conduit from wires and cut wires as close to soldered joints as possible.

2) The diodes may be tested at this point, prior to further disassembly. Care should be exercised with insulating busings under positive diode carrier. To remove negative carrier, extract threaded studs. When one rectifying diode has been damaged due to short circuiting, the three complementing diodes must be replaced also. Unscrew nuts on both "B+" terminal bolts and lift positive diode carrier (heat sink) up and back.

TESTING & REPAIRING

Diode Assemblies - test diodes with a suitable alternator tester (EFAW 192) before dismantling slip ring end frame further. CAUTION - Do not lay positive diode carrier on housing or false reading will be obtained. Disconnect conductor from "D+" to the exciter diodes at the exciter diodes heat sink. Unscrew spring and brush holder and remove from alternator. Unsolder stator lead and negativediode connection. Unscrew exciter diodes heat sink  and remove together with positive diodes heat sink.

NOTE - Before further testing, lightly clean all components in gasoline or trichlorethylene, but do not soak.

Stator - Test stator for short circuits to ground, using suitable tester (EFAW 84). Test voltage should be 40V AC. Measure resistance of stator windings between phase connections. See specifications for proper value.

Rotor  - 1) Test claw pole rotor for short circuits to ground. Test voltage should be 40V AC. Measure resistance of exciter (field coil) in rotor with ohmmeter. See Specifications for proper value. Turn down slip rings on a lathe, using suitable tailstock chuck (EFAW 75 or GDF 85 R 3).

2) After turning, check concentricity of slip rings with dual gauge. Runout should not exceed .001" (.03 mm). Minimum diameter of slip rings may be 1.25" (31.5 mm). Maximum runout of pole wheel must not exceed .002" (.05 mm).

Diode Replacement - 1) On all except 0 120 400 600 series alternators, set diode plate on press die and force diodes out with plunger. Place diode plate (without diodes) onto suitable guide pilot (EFLJ 57/0/5) and set diode seat with suitable sleeve (EFLJ 57/0/3). Smear silicone oil on diode seat, place diode palte on press die and press diodes into position. After pressing in, test all diodes.

2)  On 0 120 400 600 series alternators, set slip ring end frame on press die and force out defective diode. Coat diode seat with silicone oil and press in new diode. Test all diodes after replacement.

Drive End Frame - Check ball bearings for wear and replace as necessary. Lubricate bearings on one side. Press ball bearing into drive end frame with shielded side downward. Screw on retainer plate. Press ball bearing onto rotor (slip ring end), then press drive end frame onto rotor.

Carbon Brushes - Unsolder and replace carbon brushes. Do not allow solder to run into copper stands of brush leads. Minimum brush length is .55" (14 mm). After installation of new brushes, test for free movement.

REASSEMBLY & TESTING

1) On all except 0 120 400 600 series alternators (steps 1 through 4), fit negative diodes heat sink and clamps. Screw in double end bolts (shorter threads outward). NOTE - Left clamp is longer than right. Replace insulating washers and bushings. Test terminal bolt "B+" for short circuit to ground. Test voltage should be 80V AC.

2) Position positive diodes heat sink (carrier) and secure with insulating and spring washers. NOTE -

INSTALLATION OF DIODES

Use insulating cap NO. 1 120 502 000 instead of insulating washer on bolt nest to terminal marked "D+/61". Tighten hex nuts.

3) Place stator in slip ring end frame. Draw positive and negative diode leads together and lip through an insulating sleeve. Push sleeve over lead of exciter diode and stator connections cable. Crimp a metal ring around end of leads and solder. Cut off any excess wire protruding through ring. Reposition wiring and attach in holding clamps.

4) Side insulating sleeve over exciter diode terminal. Insulating sleeves of stator connection lead must  project over edge of negative diodes heat sink. Clamp connections firmly. 

5) On 0 120 400 600 series alternators (step 5 through 7), test both "B+" terminal bolts for short circuit to ground. Test voltage should be 80V AC. Before fitting exciter diodes heat sink (carrier), solder three positive diode terminal leads onto heat sink from below.

6) After fitting exciter diodes heat sink, solder stator leads, negative and exciter diodes to the "COMB". NOTE - Use caution, do not overheat negative diodes. Install brush holder. Raise and secure carbon brushes before installing. Screw conductor "D+" onto exciter diodes heat sink.

7) Place wave spring washer into ball bearing fit. Rub ball bearing seat with suitable lubricant. Insert rotor with drive end bearing into slip ring end frame and secure. Springs are to be set onto carbon brushes by pressing on brush with a screwdriver. Brush spring pressure will seat brushes automatically.

8) Rub suitable lubricant into ball bearing seat of slip ring end frame. Install claw pole rotor with drive end frame. Check position of stator relative to end frame. Position brush holder plate. Tighten screws. Install fan belt pulley. Coat newly installed positive diodes with chlorinated rubber lacquer.

BMW General Hydraulic Brake Troubleshooting Guide 1973-75

HYDRAULIC BRAKE TROUBLE SHOOTING

BRAKE INSPECTION & TESTING

Inspect brakes at frequent intervals for pedal reserve (clearance between pedal and toeboard with pedal firmly depressed, while brakes are cold). Increase pedal reserve by adjusting brake shoe to drum clearance. Brakes should be tested on dry, clean reasonable smooth, level roadway (not and heavy pressure. CAUTION - Do not lock wheels and slide tires on raodway.

CONDITIONS AFFECTING BRAKE PERFORMANCE

Following external conditions may affect brake performance and should be corrected before proceeding with trouble shooting of brake mechanism;

Tires - Should be same size on each side of vehicle with approximately same tread design and inflation.

Loading - Wheels should be equally loaded, as heavily loaded wheels require more braking power.

Suspension - Faulty shock absorbers, incorrect front end alignment, or loose wheel bearings may give impression brake are too severe.

TROUBLE SHOOTING DRUM BRAKES

LOW PEDAL OR EXCESSIVE TRAVEL

Fluid low. Improper brake fluid. Air in system. Hoses expand under pressure. Wheel bearings or steering parts loose. Improper brake adjustment. Distorted shoes or linings. Master cylinder of power assist unit malfunction. Defective brake lines. Improper brake pedal free travel.

PEDAL APPLIED; NO BRAKING ACTION

Air in system. Leak past primary cup in master cylinder. Piston pushed back into bores. Hydraulic leak. Rear brakes out of adjustment.

ONE WHEELS DRAGS

Front wheel bearings loose. Shoes adjusted too tight. Shoe return spring broken or weak. Piston stuck or cups distorted. Clogged line or hose. Drum out-of-round. Loose anchor pin. Distorted shoe. Defective lining.

REAR BRAKES DRAG.

Improper adjustment. Parking cable frozen.

ALL WHEELS DRAG

Improper adjustment. Defective master cylinder. Improper adjustment of master cylinder push rod. Pedal linkage binding. Defective power unit.

VEHICLE PULLS TO ONE SIDE

Uneven tire treads. Worn front end parts. Incorrect front end alignment. Front wheel bearing loose. Loose steering. Loose backing plate or anchor pins. Loose or broken springs or "U" bolts. Improper lining. Improper adjustment. Defective drum. Loose or broken return spring. Defective wheel cylinder. Improper wheel cylinder size. Clogged or crimped line.

BRAKES SQUEAK OR NOISY

Improper lining. Lining loose on shoe. Foreign material on lining. Shoes scraping backing plate. Improper adjustment. Defective drum. Defective wheel cylinder. Weak or broken return springs. Loose anchor pin, wheel cylinder, or backing plate. Brake drum silencer spring missing (if equipped).

BRAKES FADE (FAIL TO HOLD)

Excessive heat build-up. Improper linings. Drums too thin. Lining soaked with fluid, or oil. Improper fluid.

PULSATING BRAKE PEDAL

Drums out-of-round. Loose brake drum. Worn or loose bearings. Bent rear axle.

HARD PEDAL

Grease or fluid on lining. Improper brake lining or fluid. Improper adjustment. Pedal linkage binding. Faulty master cylinder. Glazed linings. Defective brake drums.

BRAKES CHATTER

Improper shoe adjustment. Loose backing plate. Foreign material on lining.  Weak or broken return spring. Loose wheel bearings. Drum out-of-round. Distorted or misaligned shoes. Frozen strut rod bushings.

SNAPPING NOISE IN FRONT END.

Grooved backing plate pad. Lack of lubrication on moving parts. Loose drums or backing plate. Loose or worn front end parts. Defective lining.

POWER BRAKE UNIT DOES NOT BOOST

Test For Power Unit Operation - Stop engine and apply pedal pressure several times to remove all vacuum from system. Hold pressure on pedal and start engine. Pedal will move slightly forward when cylinder is operating.

Power Unit Does Not Operate - Vacuum check valve stuck closed. Vacuum pipe bent, broken or closed. Insufficient engine vacuum. Blocked air inlet. Air valve sticking in diaphragm. Faulty diaphragm. Faulty piston seal. Internal leaks.

Fig. 1 Sectional View of Typical Hydraulic Brake System

TROUBLE SHOOTING DISC BRAKES

LOW PEDAL OR EXCESSIVE TRAVEL

Fluid level low. Air in system. Defective brake lines. Defective caliper. Distorted pads or linings. Master cylinder or power assist unit malfunction. Misaligned piston and pad assembly. Low pedal after hard cornering or driving on rough road (pump pedal to correct). Disc runout excessive. Damaged caliper piston seal. Metering valve for front brakes not working Caliper seals soft or swollen. Improper brake pedal free travel.

HARD PEDAL

Master cylinder or power unit malfunction. Brake fluid, oil, or grease on linings. Lines or hoses kinked, dented, or collapsed. Cylinder cups swollen. Linings worn. Incorrect lining. Frozen or seized pistons. Metering valve or cylinder bores corroded. Pedal linkage binding.

PULLING OR GRABBING

Defective master cylinder. Defective caliper. Grease or fluid on linings. Defective brake lines. Metering valve malfunctioning. Power unit malfunctioning. Defective rotor. Loose or broken front end parts. Defective rear drum. Unmatched tires. Loose or broken rear springs.

PEDAL GOES SLOWLY TO FLOOR

Air in system. Hoses or lines soft (expand under pressure) or damaged. Master cylinder primary cup damaged, bore worn, or corroded. Improper fluid. Bleeder screw open.

NOISE, CHATTER, OR PULSATION

Defective rotor. Disc pad or rotor out of parallel. Anti-rattle spring missing or out of position. Excessive clearance between disc pad and caliper. Disc pad rubbing on caliper housing. Caliper binding on mounting bolts. Rear drums defective. Wheel bearings loose. Wheel nuts loose. Wear sensor contacting rotor

DRAGGING BRAKES

Defective brake line or hose. Defective master cylinder. Residual pressure valve installed in outlet to front brakes. Power unit push rod out of adjustment. Sticking pedal linkage. Metering valve defective or incorrectly installed. Defective power unit. Defective caliper.

REAR BRAKES SKIDDING (HARD PEDAL APPLICATION)

Defective proportioning valve.

BMW 320i 530i 630Csi 1977 Brake Repair Guide

DESCRIPTION

Brake system is hydraulically operated. System uses both a tandem master cylinder and power brake unit. 530i and 630CSi models have 4 piston ATE  front disc brakes and 2 piston ATE rear brakes. 320i models are equipped with 2 piston ATE front disc brakes and drum rear brakes. Parkng brake is lever actuated and cable operated. On 530i and 630CSi models, brake shoes work against a drum machined in rear disc brake rotor/hub. On 320i models, shoes lock against rear brake drum. All models are equipped with a brake pressure regulator to reduce line pressure to rear brakes.

ADJUSTMENT

Disc Pads

320i - Raise vehicle. Release parking brake. Using special tool 34 2 000 (or equivalent wrench), tighten brake shoes by turning left cam counterclockwise and right cam clockwise. Loosen cam 1/8 turn or until wheel is just free to turn.

PARKING BRAKE

530I & 630CSi - 1) Release parking brake lever, raise and support vehicle, and remove rear wheels. Insert a brake adjusting tool through .6" hole in rotor, turn adjuster until rotor can no longer be rotated, then back off adjuster 2 or 3 teeth.

2) Work inside drive compartment, tighten adjustment nuts on lever until parking brake holds vehicle securely before fifth ratchet stop is reached.

320i - 1) Raise and support rear of vehicle. Fully release parking brake. Tighten brake shoes until wheel is locked. Back off adjusters about 1/8 turn or until wheel can just barely turn.

2) Work in inside drivers compartment and tighten nuts on lever until parking brake holds vehicle securely before fifth ratchet stop is reached.

HYDRAULIC SYSTEM BLEEDING

NOTE - Manufacturer recommends replacing brake fluid in entire system once a year to avoid moisture build-up. Attach a pressure bleeder to master cylinder reservoir.

CAUTION - Do not exceed 29 psi. Raise and support vehicle and remove wheels. Attach a bleeder hose to bleeder screw, and immerse opposite end of hose into a container partially filled with brake fluid. Open bleeder screw, allow all air to escape, then close bleeder screw. Continue operation until all air has been expelled from system. NOTE - On front wheel four piston calipers, bleed lower inboard screw before bleeding lower outboard screw.

REMOVAL & INSTALLATION

DISC PADS

Removal - Raise and support vehicle and remove wheels. Drive out retaining pins toward inside of vehicle

Fig. 1 Piston Alignment for Dual Piston
Calipers

and remove cross spring. Using an extractor tool, remove disc pads from caliper assembly. If disc pad thickness (including backing) has been worn to .080" (.02 mm), replace pads. Only replace pads in sets.

Installation - 1) Using a cylinder brush, clean guide surface and support surface in caliper. Siphon sufficient fluid from master cylinder reservoir to prevent overflowing then press pistons to bottom of bores.

2) On rear two piston calipers, ensure machined position of piston face makes a 20 degree angle to lower caliper wall. Install disc pads, cross spring, and retaining pins. After installation, depress brake pedal several times to position pads against rotor.

CALIPER ASSEMBLY

Removal - Drain brake fluid from master cylinder reservoir. Remove caliper mounting bolts. Disconnect disc pad wear indicator electrical lead. Disconnect brake fluid inlet lines. Lift caliper off rotor.

Installation - Reverse removal procedure and bleed hydraulic system.

ROTOR

Removal: 530i; Front - With caliper assembly removed, remove hub grease cap, cotter pin, and nut. Remove hub and rotor assembly. Remove Allen head bolts retaining rotor to hub and remove rotor.

NOTE - Both brake rotors must be replaced at the same time.

Installation - To install, reverse removal procedure. Tighten all bolts and fittings evenly. Bleed hydraulic system if necessary. Adjust front wheel bearings. See Wheel Bearing Adjustment in WHEEL ALIGNMENT Section.

Removal: 320i & 630CSi; Front - Raise and support front of vehicle. Separate bracket from strut. Remove caliper and tie out of way with brake line still connected. Remove mounting bolt from hub and take off rotor.

NOTE - Inboard vented brake discs are balanced, DO NOT move or replace balance clips.

Installation - To install, reverse removal procedure.

Removal 530i & 630CSi; Rear - Raise vehicle and support on safety stands. Remove tire and wheel. Remove caliper and support out of way leaving brake line connected. Slip brake line out of clamp. Take out mounting bolt and remove brake rotor.

NOTE - Both rotors must be replaced at same time. Also, inboard vented brake disc are balanced, DO NOT move or replace balance clips.

Installation - To install, reverse removal procedure.

PARKING BRAKE SHOES

Removal - With rear caliper and rotor removed, disconnect lower return spring using brake spring pliers. Turn retaining spring 90 degrees using removal tool, then set spring aside. Pull brake shoes apart at bottom and lift upward

Installation - Reverse removal procedure and adjust parking brake shoes and cables.

BRAKE DRUM

Removal & Installation: 320i; Rear - Loosen brake adjuster cams. Remove countersunk Allen bolt and slide off brake drum. To install, reverse removal procedure and note: If one brake drum is reground, drum on other side must also be machined.

BRAKE SHOES

Removal: 320i; Rear - Remove brake drum. Disengage mounting spring, retainer, and pin from each shoe. disconnect bottom return spring. Pull shoes apart and out of wheel cylinder . Disconnect parking brake cable and remove brake shoes. If brake shoe lining was worn to .118" (3.0 mm) or less, replace brake shoes.

Installation - Reverse removal procedure and note: Connect long end of spring between parking brake lever and brake shoe.

WHEEL CYLINDER

Removal: 320i; Rear - Remove brake drum. Disconnect brake fluid inlet line. Remove wheel cylinder

Fig. 2 Exploded View of 320i Rear Wheel Cylinder

bleeder valve. Remove cylinder, mounting bolts and take off cylinder being careful not to drop brake fluid on brake shoes.

Installation - To install, reverse removal procedure and make sure to bleed brake system.

MASTER CYLINDER

Removal - Siphon off brake fluid from reservoir. On 320i models, disconnect clutch hose connection. On 630CSi models, remove air cleaner. Disconnect all hydraulic lines from master cylinder. Remove nuts mounting master cylinder. Remove nuts mounting master cylinder to power booster. On 320i models, remove nuts mounting master cylinder support to inner fender panel. Remove support and master cylinder.

Installation - To install, reverse removal procedure and note: Make sure "O" ring on master cylinder is not damaged. An imperfect fit will not allow correct vacuum build-up.

POWER BRAKE UNIT

NOTE - Mixture control unit must be removed to take off power brake unit (with master cylinder).

Fig. 3 Disassembled View of Dual Piston Rear Disc
Brake for 530i & 630CSi. Front Caliper for
320i is Similar

Removal: 320i - 1) Remove air intake ducting. Remove 3 screws located in top of control unit. Spread open cable clips. Remove wire holder. Lift up mixture control unit and retain piston with fingers until it can be tapped into place. Disconnect remaining vacuum lines. Remove unit mounting nuts and lift off unit.

2) Siphon out brake fluid from reservoir. Disconnect push rod from brake pedal. Separate hydraulic lines from master cylinder. Also disconnect clutch hose.

3) Disconnect vacuum hose from brake unit. Remove brake unit mounting nuts and bolts. Separate master cylinder support from inner  fender panel. Slide master cylinder and power brake assembly from vehicle.

Installation - To install master cylinder and power brake assembly as a unit, reverse removal procedure.

Removal: 530i & 630CSi - Disconnect power brake push rod from brake pedal at clevis pin. Disconnect

vacuum hose at power brake unit. Disconnect and plug brake lines at master cylinder. remove brake unit at mounting bracket and slide entire unit out of vehicle

Fig. 4 Exploded View of 320 Rear Drum Brake Assembly

Installation - To install brake unit with master cylinder connected, reverse removal procedure. Bleed brake system after assembly is installed.

Check Valve Replacement - Check valve is located in power unit vacuum line at intake manifold. To remove, loosen hose clamps, remove vacuum hoses, and remove valve. To install, reverse removal procedure, making sure arrow or black portion of valve faces intake manifold.

Filter Replacement - With power brake unit removed from vehicle, pull back rubber dust boot and remove retaining ring. Remove silencer and filter. To install, reverse removal procedure.

OVERHAUL

Fig. 5  Four Piston Disc Brake Caliper Assembly  for 530i & 630CSi

Disassembly - With caliper removed from vehicle and disc pads remove from caliper, remove clamping rings and rubber protecting caps. Hold one piston in place using a suitable clamp, insert a piece of wood in caliper cavity, then apply compressed air to fluid inlet and remove opposite piston. Remove sealing ring using a suitable plastic tool. Remove remaining piston(s) and seal(s) in same manner. NOTE - DO NOT assemble, remove expansion bolts, separate caliper halves, and remove sealing rings.

Cleaning & Inspection - Clean all parts in alcohol and check for wear or damage; replace parts as necessary.

Reassembly - Reassemble caliper (if separated) using new seals and expansion bolts. Tighten epxansion bolts from inside out. Coat pistons and caliper bores with ATE brake cylinder paste (or equivalent), install sealing rings, then install pistons into bores. Make sure pistons are not tilted when inserting. On two piston calipers, make sure machined surface of piston face makes a 20 degree angle to lower caliper wall. Install rubber protecting caps and clamp rings.

MASTER CYLINDER

Fig. 6 Master Cylinder Primary Piston Assembly

Disassembly - Push i non primary piston and remove secondary piston stop screw. Remove snap ring from end of cylinder and remove primary and secondary piston assemblies and return spring. Disassemble piston assemblies noting number and position of parts used.

Cleaning & Inspection - Clean all parts in alcohol and inspect for wear or damage. NOTE - Cylinders with surface defects in bores must be replaced; do not overhaul.

Reassembly - Reassemble piston assemblies using thin coating of ATE brake paste. Install piston assemblies

Fig. 7 Master Cylinder Secondary (Front) Piston Assembly

into cylinder bore using a suitable guide sleeve (BMW 34 3 000) to prevent damaging seals. Install secondary piston stop screw, making sure that piston is pushed fully forward before screw is installed and tightened. Install retaining ring in end of master cylinder bore.

BMW 1976 Models 6 Cylinder Brake Repair Guide

For:

3.0

530i

DESCRIPTION

Brake system is hydraulically actuated, using a tandem master cylinder and a power brake unit. All models use four wheel ATE disc brakes. Front brakes are four piston caliper type and the rear use two piston fixed caliper type and the rear use two piston fixed caliper type. Parking brake is cable actuated, operating conventional type brake shoes against a drum machined in rear disc brake rotor casting.

ADJUSTMENT

Disc Pads

Front and rear disc brake assemblies are self-adjusting, therefore, no adjustment in service is required.

Parking Brake

Release parking brake lever, raise and support vehicle, and remove rear wheels. Insert a brake adjusting tool through .6" hole in rotor, turn adjuster until rotor can no longer be turned, then back off adjuster two or three teeth. Working inside driver compartment, tighten adjustment nuts on lever until parking brake holds vehicle securely before fifth ratchet stop is reached.

HYDRAULIC SYSTEM BLEEDING

NOTE-Manufacture recommends replacing brake fluid in entire system once a year to avoid moisture build-up. Attach a pressure bleeder to master cylinder reservoir. 

CAUTION-Do not exceed 29 psi.  Raise and support vehicle and remove wheels. Attach a bleeder hose to bleeder screw, and immerse opposite end of hose into a container partially filled with brake fluid. Open bleeder screw, allow all air to escape, then close bleeder screw. Continue operation until all air has been expelled from system. NOTE - On front wheel four piston calipers, bleed lower inboard screw before bleeding lower outboard screw.

REMOVAL & INSTALLATION

DISC PADS

Fig. 1 Piston Alignment - Calipers with Dual Piston

Removal - Raise and support vehicle and remove wheels. Drive out retaining pins toward inside of vehicle and remove cross spring. Using an extractor tool, remove disc pads from caliper assembly.

Installation - 1) NOTE - Replacement of disc pads should be done in complete sets only. Using a cylinder brush, clean guide surface and support surface in caliper. Siphon sufficient fluid from master cylinder reservoir to prevent overflowing, then press pistons to bottom of bores.

2) On rear two piston calipers, ensure machined position of piston face makes a 20 degree angle to lower caliper wall. Install disc pads, cross spring, and retaining pins. After installation, depress brake pedal several times to position pads against rotor.

CALIPER ASSEMBLY

Removal - Remove master cylinder reservoir cap and plug fluid outlet lines. Raise and support vehicle and remove tire and wheel assembly. Disconnect hydraulic line(s), remove caliper mounting bolts, and separate caliper from backing plate.

Installation - Reverse removal procedure and bleed hydraulic system.

ROTOR

Removal & Installation (Front) - With caliper assembly removed, remove hub grease cap, cotter pin, and nut. Remove hub and rotor assembly. Remove Allen head bolts retaining motor to hub and remove rotor. To install, reverse removal procedure, tighten all bolts and fittings evenly, and bleed hydraulic system if necessary. Adjust front wheel bearing. See Wheel Bearing Adjustment in WHEEL ALIGNMENT Section.

Removal & Installation (Rear) - Remove rear wheel and caliper assembly, then pull rotor out from axle shaft flange. To install, reverse removal procedure and note the following: Properly align holes in rotor with axle shaft flange. Tighten all bolts and fittings evenly and bleed hydraulic system, if necessary.

PARKING BRAKE SHOES

Removal - With rear caliper and rotor removed, disconnect lower return spring using brake spring pliers. Turn retaining spring 90 degrees using removal tool, then set spring aside. Pull brake shoes apart at bottom and lift upward.

Installation - Reverse removal procedure and adjust parking brake shoes and cables.

MASTER CYLINDER

Removal - Remove master cylinder reservoir cap and plug fluid outlet lines. Remove hose fittings from master cylinder and raise above reservoir fluid level. Mark hydraulic lines for reassembly reference and disconnect from master cylinder. Remove nuts attaching cylinder to power unit, and separate master cylinder from power brake unit.

Installation - Reverse removal procedure and note the following: Make sure rubber "O" ring seal between master cylinder and power unit is not damaged. Check clearance between power unit thrust rod and master cylinder piston with Plastigage and, if necessary, set to .020" by inserting a shim behind plunger head. Bleed hydraulic system and check for fluid leaks.

POWER BRAKE UNIT

Removal, 3.0 - 1) Remove air cleaner and battery, disconnect oil reservoir from power steering (if equipped) and move to one side. Black brake fluid reservoir outlets and remove lines from master cylinder.

Fig. 2  Disassembled View of  Dual
Piston Rear Disc Brake

2) Remove lower left instrument panel housing and secure to one side. Remove brake pedal clevis pin, and disconnect vacuum hose from intake manifold. Remove hydrauli lines from master cylinder marking positions for reassembly reference. Remove nuts retaining power unit to support and remove power unit.

Installation - To install, reverse removal procedure, bleed hydraulic system and check following adjustments: Adjust push rod (A) length to 14.49-14.53" (368-369 mm). Adjust pedal height (B) to 9.65" (245 mm). Adjust exposed depth of brake light switch plunger (C) to .240-.280" (6-7 mm). See Fig. 3.

Removal, 530i - Siphon some brake fluid from master cylinder. Unbolt coolant reservoir and position out of way. Disconnect brake pedal push rod shaft. disconnect vacuum hose at power brake unit (servo). Separate each brake line from master cylinder and mark each for reinstallation reference. Unbolt power brake unit holder and remove.

Installation - To install, reverse removal procedure, bleed hydraulic system, and check following adjustments: Adjust pedal height (B) 9.05" (230 mm) for manual transmission models and 8.66" (220 mm) for automatic transmission models. Adjust exposed depth of brake light switch plunger (C) to .200" (5 mm). See Fig. 3.

Fig. 3 Power Brake Unit Push Rod Measurement Locations

Check Valve Replacement - Check valve is located in power unit vacuum hoses, and remove valve. To install, reverse removal procedure, making sure arrow or black portion of valve face intake manifold.

Filter Replacement - With power brake unit removed from vehicle, pull back rubber dust boot and remove retaining ring. Remove silencer and filter. To install, reverse removal procedure.

OVERHAUL

Brake Caliper

Fig. 4 Four Piston Front Brake
Caliper Assembly

Disassembly - With caliper removed from vehicle and disc pads removed from caliper, remove clampingDO NOT Separate caliper halves unless a leak is detected. To disassemble, remove expansion bolts, separate caliper halves, and remove sealing rings.

rings and rubber protecting caps. Hold one piston in place using a suitable clamp, insert a piece of wood in caliper cavity, then apply compressed air to fluid inlet and remove opposite piston. Remove sealing ring using a suitable plastic tool. Remove remaining piston(s) and seal(s) in same manner. NOTE -

Cleaning & Inspection - Clean all parts in alcohol and check for wear or damage, replace parts as necessary.

Reassembly - Reassemble caliper (if separated) using new seals and expansion bolts. Tighten expansion bolts from inside out. Coat pistons and caliper bores with ATE brake cylinder paste (or equivalent), install sealing rings, then install pistons into bores. Make sure pistons are not tilted when inserting. On two piston calipers, make sure machined surface of piston face makes a 20 degree angle to lower caliper wall. Install rubber protecting caps and clamp rings.

MASTER CYLINDER

Disassembly - Push in an primary piston and remove secondary piston stop screw. Remove snap ring from end of cylinder and remove primary and secondary piston assemblies and return spring. Disassemble piston assemblies noting number and position of parts used.

Fig. 5 Master Cylinder Primary
Piston Assembly

Cleaning & Inspection - Clean all parts in alcohol and inspect for wear or damage. NOTE - Cylinders with surface defects in bores must be replaced; do not overhaul.

Reassembly - Reassemble piston assemblies using thin coating of ATE brake paste. Install piston assemblies into cylinder bore using a suitable guide sleeve (BMW 34 3 000) to prevent damaging seals. Install secondary piston stop screw, making sure that piston is pushed fully forward before screw is installed and tightened. Install retaining ring in end of master cylinder bore.

BMW 4 Cylinder Models 1976 Brake Repair Guide

DESCRIPTION

Brake system is hydraulically operated using a tandem master cylinder and a power brake unit. Front disc brakes consist of rotors attached to wheel hubs, and four piston fixed calipers attached to steering knuckles. Rear brakes are leading-trailing shoe/drum, type, using a dual piston wheel cylinder. Parking brake is cable operated, activating secondary shoes of rear brake assemblies.

ADJUSTMENT

FRONT DISC BRAKE PADS

Front disc brakes are self-adjusting, therefore, no adjustment in service is required.

REAR DRUM BRAKES

Raise and support rear of vehicle and release parking brake. Using an offset wrench (BMW 6038), tighten left eccentric nut counterclockwise and then right eccentric nut clockwise until wheel is locked. NOTE - Rotate tire while making sure adjustments. Loosen each adjuster until wheel is just free to rotate.

PARKING BRAKE

With rear brakes properly adjusted, pull back rubber boot on parking brake lever and loosen lock nuts. Pull brake lever up to fifth ratchet stop and check for braking action at rear wheels. If adjustment is required, tighten adjusting nuts until rear wheels are locked. Tighten lock nuts and ensure wheels turn freely with parking brake lever released.

HYDRAULIC SYSTEM BLEEDING

NOTE - Manufacturer recommends replacement of brake fluid in entire system once are year to avoid moisture build-up. Attach a pressure bleeder to master cylinder reservoir. NOTE - DO NOT exceed 29 psi. Raise vehicle and remove front wheels. Attach a bleeder hose to bleeder screw and immerse opposite end of hose into a container of brake fluid. Open bleeder screw, allow air to escape, then close bleeder screw. Continue operation until all air to escape, then close bleeder screw. Continue operation until all air has been bled from system. NOTE - On front disc brakes, bleed lower inboard screw before bleeding lower outboard screw.

REMOVAL AND INSTALLATION

FRONT DISC BRAKE PADS

Fig. 1 Installed View of BMW 2002 Disc Brake and Caliper

Removal - Raise and support front of vehicle and remove wheels. Drive retaining pins out toward center of vehicle and remove cross spring. Using a suitable pulling tool, remove brake pads. If pads are to be reinstalled, mark for reassembly reference. NOTE - Pads are not interchangeable.

Installation - NOTE - Replacement of disc pads should be done in complete sets only. Using a cylinder brush, clean guide surface and support surface in caliper. NOTE - DO NOT use oil based solvents. Siphon sufficient fluid from master cylinder reservoir to prevent overflowing, then press pistons to bottom of bores. Install disc pads, cross spring, and retaining pins. Pump brake pedal several times to position pads against rotor.

FRONT DISC BRAKE CALIPER

Fig. 2 Attaching Points of  Brake Caliper and
Hydraulic Lines

Removal - Raise and support front of vehicle and remove wheels. Disconnect hydraulic lines and plug openings. Remove bolts securing caliper to steering knuckle and remove caliper.

Installation - Reverse removal procedure and note the following: Left and right calipers are not interchangeable. When installed, bleeder screws must face upward. Tighten all bolts and fittings evenly and  bleed hydraulic system.

FRONT DISC BRAKE ROTOR

Removal - Remove caliper. NOTE - Do not allow caliper to hang from hydraulic line after removal; support out of way. Remove Hub grease cap, cotter pin and nut, then remove hub and rotor assembly from axle. Remove Allen bolts and separate brake rotor from wheel hub.

Installation - Install rotor onto wheel hub and tighten bolts securely. Install hub and rotor assembly onto axle, install outer wheel bearing, washer and nut. Adjust wheel bearings and install cotter pin and grease cap. See Wheel Bearing Adjustment in WHEEL ALIGNMENT Section. Install caliper and bleed hydraulic system if necessary.

REAR BRAKE DRUM

Removal - Remove tire and wheel assembly and loose eccentric adjusting nuts. Pull drum straight out from axle to remove.

Installation - Install brake drum to axle, install tire and wheel assembly, and adjust brake shoes and parking brakes (if required).

REAR BRAKE SHOES

Removal - With brake drum removed, remove shoe spring at bottom of brake assembly and pull shoes out from wheel cylinder. Disconnect parking brake cable from lever, remove return spring and strut, and remove brake shoes.

Fig. 3 Exploded View of Rear Drum Brake Assembly

Installation - Reverse removal procedure and note the following: Make sure long end of upper return spring is installed between parking brake lever and brake shoe. Ensure brake shoe spring at bottom of assembly is installed behind support plate.

REAR BRAKE WHEEL CYLINDER

Removal - With brake drum removed, disconnect hydraulic line, and remove bleeder screw and wheel cylinder attaching bolts. Using an offset wrench (BMW 6038), turn brake shoe eccentric adjusting nuts until shoes are spread out from wheel cylinder as far as possible. Remove wheel cylinder maneuvering out of backing plate.

Installation - Reverse removal procedure, adjust brake shoes, and bleed hydraulic system.

MASTER CYLINDER

Removal - Siphon fluid as necessary from master cylinder reservoir. If necessary, remove air cleaner assembly. Disconnect hydraulic lines from cylinder, cap all openings, and mark lines for reassembly reference. Remove attaching bolts and separate master cylinder from power unit.

Installation - Reverse removal procedure and note the following: Make sure rubber "O" ring is installed on master cylinder between cylinder and power unit. Check clearance between master cylinder piston and power unit push rod. Clearance should be .002" (.051 mm), and is adjusted by removing or installing shims behind head of power unit push rod.

POWER BRAKE UNIT

Removal - With master cylinder removed, disconnect power unit push rod from pedal assembly by removing clevis pin. Disconnect vacuum line from check valve, remove nuts attaching power unit to support, and remove power brake unit.

Installation - Reverse removal procedure, taking care to install rubber "O" ring on master cylinder between cylinder and power unit.

Check Valve Replacement - Vacuum check valve is located in vacuum line at intake manifold. To remove, loosen hose clamps, separate vacuum hoses from valve, and remove valve. To install, position check valve so that arrows or black portions of valve face intake manifold, install vacuum hoses and install and tighten clamps.

Filter Replacement - With power brake unit removed from vehicle, remove rubber dust boot, retainer, silencer and filter. To install, reverse removal procedure making sure slots in filter and silencer are offset 180 degrees in relation to one another.

OVERHAUL

FRONT DISC BRAKE CALIPER

Disassembly - 1) With caliper fitted to a vise, remove snap rings and pull out rubber protective caps. Take special care not to damage pistons.

Fig. 4 Disassembled View of BMW Disc Brake

2) Using suitable piston clamp (BMW 34 1 050), lock one piston into cylinder bore. Insert a small block of hard wood between other piston and flat surface of clamp. Apply light air pressure to inlet port and expel

Fig. 5 Forcing Piston From Position in Brake
Caliper

piston from cylinder bore.

3) Using sealing plate across bore of vacant cavity, force out second piston. Third and fourth pistons are removed in a like manner. Using a plastic instrument, dig seal from groove on cylinder bore.

NOTE - Manufacturer does not recommend separating caliper halve unless a leak is detected.

Cleaning & Inspection - Clean all parts in alcohol and dry with compressed air. Check cylinder bores, pistons, and flange surfaces for rust, corrosion, or other damage. Replace parts as necessary; do not attempt to machine caliper bores or pistons.

Reasembly - Reassemble caliper with new sealing rings and expansion bolts if halves were separated. Tighten caliper expansion bolts alternately and evenly from inside out. Coat pistons and sealing rings with ATE brake caliper paste (or equivalent) and install into caliper bores. Install protective caps.

REAR WHEEL CYLINDER 

Disassembly - Remove dust caps, then withdraw piston and seal assemblies and spring. Remove bleeder screw. Remove rubber seals from pistons.

Cleaning & Inspection - Clean all parts in alcohol. Check all parts for wear or damage; replace parts as necessary. Make sure that grooves on cylinder body are not corroded. 

Reassembly - Coat all parts with ATE brake cylinder paste (or equivalent) and reverse disassembly procedure. NOTE  - Manufacturer recommends replacing piston seals whenever cylinder has been disassembled.

MASTER CYLINDER 

Disassembly - Push in on primary piston and remove piston stop screw on top of master cylinder. Remove

Fig. 6 Master Cylinder Primary (Rear) Piston Assembly

retaining ring from end of cylinder and withdraw primary piston assembly. Use compressed air to remove secondary piston assembly from cylinder bore, then remove piston return spring. Disassemble piston assemblies, noting number and position of parts used.

Cleaning & Inspection - Clean all parts in alcohol and check for wear or damage. NOTE  - Cylinders with surface defects in bores must be replaced; do not overhaul.

Reassembly - Reassemble piston assemblies using a thin coating of ATE brake cylinder paste (or equivalent). Install piston assemblies into cylinder bore using a suitable guide.

Fig. 7 Master Cylinder Secondary (Front) Piston Assembly

Reassembly - To reassemble, reverse removal procedure and note the following: Coat all components with ATE brake paste. Ensure piston is fitted using sleeve tool (BMW 34 4 010). New piston seals are marked with paint rings; paint marks face away from each other. When installing stop screw, place pressure on piston. Always replace copper sealing ring under stop screw.

BMW 1969-73 6 Cylinder Models Brake Repair Manual

Models Covered

• 2500 (1969-70)
• 2800 (1969-70)
• 2800 CS & CSA (1969-71)
• 3.0 CS & CSA (1969-71)
• Bavaria (1972-73)

DESCRIPTION

Models 2800 CS and CSA use ATE four-piston fixed caliper disc brakes on front and leading-trailing shoe drum brake on the rear. All other models use four wheel ATE disc brakes with four-piston caliper on front and two-piston caliper on the rear. All models use twin circuit, tandem piston master cylinders. Four wheel disc brake system use a pressure limiter to control hydraulic pressure applied to rear brakes. Hydraulic pressure to rear brakes is adjustable with the pressure limiter. Hand brake actuates cable to rear brake shoes. A special duo-servo drum-disc combination is used on rear wheels with disc brakes.

ADJUSTMENT

DRUM BRAKES 

2800 CS & CSA - Release handbrake, hoist vehicle and using suitable wrench (6038) loosen each brake shoe with its eccentric adjusting screw. While revolving wheel, turn left adjusting screw counterclockwise and right screw clockwise, until wheel will no longer turn. Loosen each screw ⅛ turn at a time until wheel turns freely.

DISC PADS

Front and rear disc brake assemblies are self-adjusting, therefore, no adjustment in service is required.

PARKING BRAKE

PISTON ALIGNMENT

Disc Brakes (With Integral Drum On Rear) - Release parking brake lever, raise and support vehicle and remove rear wheels. Insert brake adjusting tool through .6" hole in rotor. Turn start wheel adjuster until rotor can no longer be turned, then back off adjuster two or three teeth. Working inside driver compartment, tighten adjustment nut on hand lever until parking brake holds vehicle (before fifth ratchet stop is reached).

Models With Rear Drum Brakes - Drum brakes must be adjusted before attempting to adjust handbrake. Handbrake should be adjusted if hand operated lever can be pulled up more than five notches. Adjust with handbrake lever completely disengage, by turning adjuster on cable and next to hand brake lever. Adjustment is correct when handbrake will lock rear wheels without passing through more than four or five notches on ratchet.

HYDRAULIC SYSTEM BLEEDING

NOTE - Manufacturer recommends replacing brake fluid entire system once a year to avoid moisture build-up. Attach a pressure bleeder to master cylinder reservoir. CAUTION - Do not exceed 29 psi. Raise and support vehicle and remove wheels. Attach a bleeder hose to bleeder screw, and immerse opposite end of hose into a container partially filled with brake fluid. Open bleeder screw, allow all air has been expelled  from system. NOTE - On front wheel four piston calipers, bleed lower inboard screw before bleeding lower outboard screw.

REMOVAL AND INSTALLATION

DRUM BRAKE SHOES

Removal - Hoist vehicle, remove rear wheels and brake drums. Detach brake shoes from bottom support, then pull shoes out of wheel cylinders. Disconnect hand brake cable from rear shoes. Separate shoes by removing return springs.

Installation - Reverse removal procedure and note the following: Install long end of shoe push rod spring toward handbrake lever. Adjust brakes.

DISC PADS

Removal - Raise and support vehicle and remove wheels. Drive out retaining pins toward inside of vehicle and remove cross spring. Using a suitable extractor tool (3.9314-14002), remove disc pads from caliper assembly.

Installation - 1) NOTE -  Replacement of disc pads should be done in complete sets only. Using a cylinder brush, clean guide surface and support surface in caliper. Siphon sufficient fluid from outer cylinder reservoir to prevent overflowing, then press pistons to bottom of bores.

2) On rear two piston calipers, ensure machines position of piston face makes a 20° angle to lower caliper wall. Install disc pads, cross spring and retaining pins. After installation, depress brake pedal several times to position pads against rotor.

CALIPER ASSEMBLY

Removal - Remove master cylinder reservoir cap and plug fluid outlet lines. Raise and support vehicle and remove tire and wheel assembly. Disconnect hydraulic line(s), remove caliper mounting bolts, and separate caliper from caliper from backing plate.

Installation - Reverse removal procedure and bleed hydraulic system.
ROTOR
Removal & Installation (Front) - With caliper assembly removed, remove hub grease cap, cotter pin, and nut. Remove hub and rotor assembly. Remove Allen head bolts retaining rotor to hub and remove rotor. To install, reverse removal procedure, tighten all bolts and fittings evenly, and bleed hydraulic system if necessary. Adjust front wheel bearing. See Wheel Bearing Adjustment in WHEEL ALIGNMENT Section.
Removal & Installation (Rear) - Remove rear wheel and caliper assembly, then pull rotor out from axle shaft flange. To install, reverse removal procedure, tighten all bolts and fittings evenly, and bleed hydraulic system if necessary.
PARKING BRAKE SHOES
Removal - With rear caliper and rotor removed, disconnect lower return spring using brake spring pliers. Turn retaining springs 90 degrees using suitable tool (7014) and remove. Pull brake shoes apart at bottom and lift away upwards.
Installation - Reverse removal procedure and adjust parking brake shoes and cables.
MASTER CYLINDER
Removal - Remove master cylinder reservoir cap and plug fluid outlet lines. Remove hose fittings from master cylinder and raise above reservoir fluid level. Mark hydraulic lines for reassembly reference and disconnect from master cylinder. Remove nuts attaching cylinder to power unit, and separate master cylinder from power brake unit.

POWER UNIT PUSH ROD ADJUSTMENTS

Installation - Reverse removal procedure and note the following: Make sure rubber "O" ring seal between master cylinder and power unit is not damaged. Check clearance between power unit thrust rod and master cylinder piston with Plastigage and, if necessary, set to .020" by inserting a shim behind plunger head. Bleed hydraulic system and check for fluid leaks.
POWER BRAKE UNIT
Removal - 1) Remove air cleaner and battery, disconnect oil reservoir for power steering (if equipped) and move to one side. Block brake fluid reservoir outlets and remove hoses from master cylinder.
2) Remove lower left instrument panel housing and secure to one  side. Remove brake pedal clevis pin, and disconnect vacuum hose from intake manifold. Remove hydraulic lines from master cylinder marking positions for reassembly reference. Remove nuts retaining power unit to support and remove power unit.
Installation - Reverse removal procedure, bleed hydraulic system, and check following adjustments: Adjust length of piston rod (A) to 14.49-14.53". Adjust pedal height (B) to 9.65". Adjust exposed depth of brake light switch plunger (C) to .24-.28". See illustration.
Check Valve Replacement - Check valve is located in power unit vacuum line at intake manifold. To remove, loosen hose clamps, remove vacuum hoses, and remove valve. To install, reverse removal procedure, making sure arrow or block portion of valve faces intake manifold.
Filter Replacement - With power brake unit removed from vehicle, pull back rubber dust boot and remove retaining ring. Remove silencer and filter. To install, reverse removal procedure.
REAR BRAKE PRESSURE LIMITER
Removal & Installation - Plug fluid outlets in brake fluid reservoir. Disconnect brake hose and rear brake lines from pressure limiter. Remove mounting bolts and pressure limiter. To install, reverse removal procedure and bleed hydraulic system.

OVERHAUL

DRUM BRAKE WHEEL CYLINDER
Disassembly - With wheel brake drum removed, back off shoe adjusting cams, disconnect brake line and remove cylinder from backing plate. Disassemble wheel cylinder and pay particular attention to location and direction of parts.
Cleaning & Inspection - Clean all parts in alcohol or other suitable non oil base solvent. Discard all rubber parts and inspect all other parts for wear or damage.
Reassembly - Dip new parts in clean brake fluid or apply ATE cylinder paste. To install cylinder, reverse disassembly procedure and bleed brakes.
BRAKE CALIPER
Disassembly - With caliper removed from vehicle and disc pads remove from caliper, remove clamping rings and rubber protecting caps. Hold one piston in place using a suitable clamp, insert a piece of wood in caliper  cavity, then apply compressed air to fluid inlet and remove opposite piston. Remove sealing ring using a suitable plastic tool. Remove remaining piston(s) and seal(s) in same manner. NOTE - DO NOT separate caliper halves unless a leak is detected. To disassemble, remove expansion bolts, separate caliper halves and remove sealing rings.
Cleaning & Inspection - Clean all parts in alcohol and check for wear or damage; replace parts as necessary.
Reassembly - Reassemble caliper (if separated) using new seals and expansion bolts. Tighten expansion bolts from inside out. Coat pistons and caliper bores with ATE brake cylinder paste (or equivalent), install sealing rings, then install pistons into bores. Make sure pistons are not tilted when inserting. On two pison calipers, make sure machined surface of piston face makes a 20 degree angle to lower caliper wall. Install rubber protecting caps and clamp rings.
MASTER CYLINDER
Disassembly - Push in on primary piston and remove secondary piston stop screw. Remove snap ring from end of cylinder and remove primary and secondary piston assemblies and return spring. Disassemble piston assemblies noting number of parts used.
Cleaning & Inspection - Clean all parts in alcohol and inspect for wear or damage. NOTE - Cylinders with surface defects in bores must be replaced; do not overhaul.
Reassembly - Reassemble piston assemblies using a thin coating of ATE brake cylinder paste (or equivalent). Install piston assemblies into cylinder bore using a suitable guide sleeve (BMW 6063) to prevent damaging seals. Install secondary piston stop screw, making sure that piston is pushed fully forward before screw is installed and tightened. Install retaining ring in end of master cylinder bore.