Automotive Brakes Systems

Brake System Principles and Operation

Introduction

RPO CodesUsually located in glove box or on spare

tire cover.Brakes information starts with “J”.

Brake System Principles and Operation

Base Brake Components

Brake System Principles and Operation

Brake Sub-Systems

Brake System Principles and Operation

Brake System OperationTraditional brake systems change kinetic

energy into heat energy through friction.

Brake System Principles and Operation

Changing Energy Energy is never created or destroyed, just changed.

Brake System Principles and Operation

Power of SystemsBrake systems must have enough power to

stop a vehicle at W.O.T.

Brake System Principles and Operation

Coefficient of FrictionForce to pull

an object divided by the weight.

Brake System Principles and Operation

Coefficients of Friction and TemperatureTemperature can have negative effects on

COF. These include fade and grab.

Brake System Principles and Operation

Traction / Weight and BalanceKeep in mind, the weight and balance of a

vehicle effects the traction of that vehicle greatly.

Wheels with more traction must have more brake force applied than those with less traction.

Brake System Principles and Operation

Brake Fluid must do the following:Maintains Viscosity

High Boiling Point

Non-Corrosive

Water Tolerant

Lubricates

Low Freezing Point

Brake System Principles and Operation

Answers to Brake Fluid FAQsThree basic types: DOT 3, 4, and 5Brake Fluid will damage painted surfaces.

Wash any spills immediately.Conventional brake fluids are hydroscopic

- that is they readily absorb moisture. Always keep brake fluid in a sealed container.

Never reuse brake fluid.

Brake System Principles and Operation

Answers to Brake Fluid FAQsDot 3 and 4 are conventional, and are

interchangeable; but are not recommended to be interchanged. DOT 4 has a higher equilibrium reflux boiling point or ERBP.

DOT 5 is silicone based, does not absorb water, and has a higher ERBP yet.

According to some manufacturers, DOT 5 can cause seal deterioration in systems designed for DOT 3 or 4.

Brake System Principles and Operation

Answers to Brake Fluid FAQsDOT 5.1 is a non-silicone-based polyglycol

fluid that is clear to amber in color. It is more popular in Europe. It has a ERBP equal to DOT 5 fluid. According to brake fluid manufacturers, DOT 5.1 can be mixed with both DOT 3 and DOT 4. Automobile manufacturers have not acknowledged this yet.

Follow published Service Information.

Brake System Principles and Operation

Brake Fluid Concerns:Contamination:

Mineral-Based OilsMoistureAir

Brake Fluid DisposalEPA mandates that brake fluid is to be

disposed of with used engine oil.Do Not Wash Down the Drain.

Brake System Principles and Operation

Brake LiningsComposition is a mixture of “stuff”. Caution

- Organic Linings may still contain asbestos.

Linings are produced in batches called “Lots”. Linings produced in two different lots may have different braking characteristics.

Lining Edge Codes identify the manufacturer, lot #, compound, & COF.

OverviewBrake System Principles and OperationBase Brake Diagnosis

Master Cylinders & Hydraulic Systems Balance Control SystemsWarning Systems

Wheel Bearings

Drum Brakes

Disc Brakes

Machining Drums and Rotors

Power Brake Boosters

Base Brake Diagnosis

Brake System Performance Evaluation

Common Brake Concerns Include: Brake VibrationGrabbing BrakesExcessive Brake Pedal EffortPulling Brakes

Base Brake Diagnosis

Common Concerns cont. Spongy Brake PedalDropping Brake PedalLow Brake PedalDragging BrakesNo Brake PedalBrake Warning Light OnBraking Noise

Base Brake Diagnosis

Brake System Inspection

Checking Brake Pedal Action Includes:Pedal HeightPedal Free-playReserve Distance

Checking Brake FluidVisual InspectionTest StripsBrake Fluid Boiling Point Tester

Base Brake Diagnosis

Checking for Leaks

Checking the Parking Brake

Disc Brake Inspection

Worn Out Friction Material 3mm min.

Material SeparationMissing or Broken Pad Clips

Base Brake Diagnosis

Disc or Rotor Damage ScoringCrackingHeat CheckingRust PittingWorn Beyond Specs.Excessive RunoutLack of ParallelismMaterial Transfer

Base Brake Diagnosis

Drum Brake Inspection Frozen (Rusted) Adjusters

Spring DamageWeakened SpringsMissing SpringsBroken Springs

Base Brake Diagnosis

Worn Out Friction Material 1.5 mm min. Material Separation

Drum Damage Cracking Hard Spots Heat Checking Scoring Worn Beyond Specs.

Material Transfer

End of Brake System Principles and Operation