Automotive Brakes – Study Guide ©2011 Melior, Inc. ____________________________________________________________________________________ TABLE OF CONTENTS I. BRAKE SYSTEM FUNDAMENTALS ............................................................................................................... 8 Heat and Brake Linings ............................................................................................................................ 10 Weight and Speed ................................................................................................................................... 12 Friction Between Tire and Road .............................................................................................................. 13 Service Brakes & Parking Brakes ............................................................................................................. 14 Brake Subsystems ................................................................................................................................... 15 Hydraulic Principles ................................................................................................................................. 16 Split Hydraulic Systems ........................................................................................................................... 18 Diagonal Split Hydraulic System.......................................................................................................... 18 Front/Rear Split Hydraulic System ...................................................................................................... 19 Regenerative Braking .............................................................................................................................. 20 II. MASTER CYLINDER .................................................................................................................................. 21 Brake Circuit Leak .................................................................................................................................... 22 Compensating Ports ................................................................................................................................ 23 Bypass Ports ............................................................................................................................................ 24 Brake Release .......................................................................................................................................... 25 Residual Check Valve .............................................................................................................................. 26 Balance Control Systems ......................................................................................................................... 27 Metering Valve ........................................................................................................................................ 28 Proportioning Valve ................................................................................................................................ 30 Pressure Differential Valve (Switch) ....................................................................................................... 31 Servicing Brake System Switches and Valves .......................................................................................... 32 Procedure for testing the differential pressure valve ......................................................................... 32 Procedure for testing the metering valve ........................................................................................... 33 Procedure for testing the proportioning valve ................................................................................... 33 III. POWER ASSIST SYSTEM .......................................................................................................................... 35 Vacuum Booster ...................................................................................................................................... 37 Hydraulic Assist Boost System ................................................................................................................ 39 Diagnosing Power‐Assisted Brake Systems ............................................................................................. 41 Diagnosing vacuum‐boost power brake systems ............................................................................... 41 Diagnosing hydraulically‐assisted power brakes ................................................................................ 42 Repairing Power Boosters ....................................................................................................................... 43 IV. DISC BRAKES .......................................................................................................................................... 44 Disc Brake Caliper ................................................................................................................................... 45 Disc Brake Rotors .................................................................................................................................... 49 Measuring rotor lateral runout ........................................................................................................... 49 Measuring rotor thickness variation ................................................................................................... 50 Rotor Refinishing ................................................................................................................................. 51 Inspect and Diagnose Disc Brake Systems .............................................................................................. 52 Visually inspecting the disc brake system ........................................................................................... 52 Determining the cause of pulsating pedal or brake fade ................................................................... 53 Service Disc Brake Calipers ..................................................................................................................... 56 Removing disc brake calipers .............................................................................................................. 56 Inspecting and repairing calipers ........................................................................................................ 57 Installing and adjusting disc brake calipers......................................................................................... 59 Service Disc Brake Rotors ........................................................................................................................ 61 Determining rotor thickness, parallelism, and runout ....................................................................... 61 Machining rotors off the vehicle ......................................................................................................... 63 Machining rotors on the vehicle ............................................................................................................. 66 Preparation for machining rotors ....................................................................................................... 66 V. Reading Micrometers ............................................................................................................................. 69 Reading an English Micrometer .............................................................................................................. 70 Reading a Metric Micrometer ................................................................................................................. 72 VI. DRUM BRAKES ....................................................................................................................................... 73 Duo‐servo Brakes .................................................................................................................................... 74 Brake Drum ......................................................................................................................................... 75 Brake Shoes ......................................................................................................................................... 75 Wheel Cylinder .................................................................................................................................... 76 Brake Anchors ..................................................................................................................................... 77 Backing Plate ....................................................................................................................................... 77 Duo‐servo Brake Operation .................................................................................................................... 78 Self‐Adjusters .......................................................................................................................................... 79 Leading‐Trailing Brake Operation ........................................................................................................... 80 Brake Drum Inspection ........................................................................................................................... 81 Measuring Brake Drums ....................................................................................................................