Brake

Question 1

What are 8 main components of the drum brakes

Answer 1

the drum, backing plate, the wheel cylinder and pistons,

the brake shoes, adjustment screw, the hold down springs and the return springs

Question 2

What is a ventilated rotor?

Answer 2

Two braking services are separated by a centre section for better cooling

Question 3

How does frictional drag impact drum brakes?

Answer 3

It pulls the shoes tight to the drum, increasing braking force

Question 4

What is needed to increase brake force for disk brakes

Answer 4

Power brake unit, because frictional drag is less.

Question 5

Advantages of disk brakes

Answer 5

More resistant heat fade, because the rotor is exposed to atmosphere dissipating heat quicker

More resistant to water fade, the rotation of the rotor tends to throw off moisture

Better straight line stopping

Automatically adjust to pad wear

Question 6

What are two types of disc brake design?

Answer 6

Fixed caliper.

Floating caliper 

Question 7

What is the function of the brake splash shield?

Answer 7

Protect the rotor from water and dirt due to road splash. It is bolted to the steering knuckle.

It is important in directing air over the rotor to help with cooling

Question 8

What is a fixed rotor?

Answer 8

The hub and rotor are cast as a single unit

Question 9

What is a floating rotor?

Answer 9

The rotor and hubs are made as two separate parts.

The rotor is less expensive and can be replaced easily

Question 10

What is the function of a brake caliper/ wheel cylinder?

Answer 10

It converts hydraulic pressure into a mechanical force

Question 11

What is the proper name for the square cut seal in the brake caliper?

Answer 11

Piston hydraulic seal

Question 12

What is the function of the piston hydraulic seal?

Answer 12

The square cut seal prevents fluid leakage between the cylinder board wall and the piston.

It also acts as a retracting mechanism for the piston when the hydraulic pressure is released.

Question 13

What allows the brake piston to move farther out to adjust for brake wear

Answer 13

Piston hydraulic seal
Also known as.. square cut seal

Question 14

What is an audible disk pad wear sensor

Answer 14

Generally Located on the leading edge. Spring steel tab makes contact with a rotor when the lighting wears down.

The sensor causes a high-pitched squeal whenever the wheel is turning, except for when the break is applied.

This noise gives a warning to the driver that the brake service is needed and perhaps saves the rotor from destruction

Question 15

What is an electronic wear indicator?

Answer 15

Wear device causes warning light in instrument panel to illuminate

Question 16

Causes for the brake warning lights to turn on

Answer 16

Red brake warning light: issue with regular brake system or park brake engaged.

Yellow brake warning light: ABS system performing self-test or there is a faulty ABS system

Blue or yellow warning light: wheels are slipping because of road conditions

Question 17

Causes for pulsating pedal

Answer 17

Vibration or shudder is felt in the pedal or steering wheel if the rotor is warped

Check the rotor for run out (dial indicator) / parallelism (thickness variation) micrometer

Question 18

What can cause a warped rotor

Answer 18

Improper tightening sequence of the wheel lug nuts.

Parallelism, rust causing vented slots to bulge

Question 19

Causes of spongy pedal

Answer 19

Feeling the need to pump the brake to get good stopping ability - cause by air in the system

Question how the air was introduced, low fluid level, leak hose, defective master cylinder

Excessive flexing in the pads or caliper and bracket.

Question 20

Causes of hard pedal

Answer 20

Issue with power brake booster.

Issue with restricted brake line or hoes. Carefully check line, including collapsed hose.

Question 21

Causes of dragging brakes

Answer 21

Vehicle feels as if it has lost or is losing power as it drives down the road.

Poor fuel economy

Check park brake booster and rear wheels to makes sure the brakes are released.

Check restricted hoses, which keep pressure at the calipers

Inspect for sticky or seized calipers

Inspect for collapsed hoses.

Question 22

Causes of grabbing brakes

Answer 22

Brake pedal seems overly sensitive, caused by contaminated brake linings/ pads

Repair the source of contaminations leaking fluid. More common with drum brakes

Question 23

Causes of noisy brakes

Answer 23

Is it a wear sensor?

Rotor rubbing on splash guard

Failure to install the anti-rattle hardware

Question 24

Causes of pulling

Answer 24

Check tire pressures and condition

Seized caliper, slide pins, frozen piston, restricted hose

Question 25

Before starting brake inspection, ensure these components are okay:

Answer 25

Tires excessive wear / inflation Wheels for damage Wheel bearings Suspension components Brake fluid level Master cylinder; brake lines & hoses; each wheel for leaks Park brake operation

Question 26

What is something that can be done to close the master cylinder ports to minimize fluid from draining

Answer 26

Slightly depress brake pedal with a depressor

Question 27

What can be done to prevent brake fluid from overflowing the reservoir

Answer 27

Remove some fluid from the master cylinder Have drain pot connected to bleed screw to prevent dirty fluid from going back into ABS system

Question 28

What is a safe pressure to remove caliper piston with compressed air

Answer 28

30psi

Question 29

What is uneven brake pad wear?

Answer 29

When a pad on one side of the rotor has worn more than the other side. Uneven pad where often meets the callipers is sticking and not giving equal pressure to both pads. Problem could be caused by poor lubrication or deformation of the machine sliding pins

Question 30

What can lateral run out cause over time

Answer 30

The wobbling of a rotor from lateral run out can cause, Parallelism. It can also cause excessive pedal travel

Question 31

What specification should lateral runout be less than

Answer 31

0.08mm of 0.003”

Question 32

How is lateral runout measured?

Answer 32

With a dial indicator Check for bearing end play is within spec. Place dial indicator so that it’s tip contacts the rotor at 90° and the indicator tip is 25m (1”) from the outer edge of the rotor Turn the rotor a full rotation and compare the lowest to highest reading. The difference = maximum runout

Question 33

Checking for Parallelism and thickness variation

Answer 33

Place micrometer 25mm from outside edge of rotor Compare measurements at 6-8 locations and record them If the rotor is thinner than the minimum thickness at any point, or if the thickness variation exceeds limits, it must be replaced Many manufacturers hold tolerance on thickness variation as close as 0.013 mm or 0.0005”

Question 34

Additional rotor inspection points

Answer 34

Grooves and scoring, any rotor having score marks more than 0.38 mm or 0.015” should be refinished or replaced. Cracks Heat checking: heat checking appears as many small interlaced cracks Bluing or hard spots cannot be machined. Rust inspect the fins of vented rotors for rust as it could lead to thickness variation / parallelism

Question 35

Process for bedding in brake pads

Answer 35

20x 50 to 30kph stops 20x 80 to 30kph slow downs 5x moderate stops from 65 to 15kph without letting the brakes cool

Question 36

What returns the calliper piston away from the rotor during brake release

Answer 36

Caliper square cut seal

Question 37

What allows the brake calliper to be self adjusting?

Answer 37

The caliper square cut seal

Question 38

Where is the Audible wear sensor tab located on the brake pad?

Answer 38

At the leading edge 

Question 39

What prevents moisture from entering the caliper bore?

Answer 39

The dust boot

Question 40

What is the recommended maximum air pressure used to force the piston from the caliper?

Answer 40

207 kPa / 30psi

Question 41

What directs air flow over the exposed rotor surface

Answer 41

Splash shield

Question 42

What is the maximum pad taper allowed before replacement is required

Answer 42

3.18mm (1/8”)

Question 43

What could cause only the left front disc brake assembly to drag?

Answer 43

A restricted brake hose

Question 44

Which term refers to variation in thickness of the rotor

Answer 44

Parallelism

Question 45

What causes the formation of hard spots in the rotor

Answer 45

Overheating

Question 46

Which of the following is likely to cause pulsating brake pedal A damage brake flex hose. Warrant brake pad linings. Excessive lateral run out. Parallel rotors 

Answer 46

Excessive lateral run out

Question 47

What tool should be used to measure rotor lateral run out?

Answer 47

Dial indicator

Question 48

What type of rotor is usually used on a larger vehicle?

Answer 48

Ventilated rotors

Question 49

In a typical drum break, which component provides a foundation for the brake shoes and associated hardware

Answer 49

Backing plate

Question 50

How is the trailing shoe of a leading-trailing brake assembly applied

Answer 50

Wheel cylinder hydraulic force only

Question 51

Which of the following statements about drum breaks is correct - web thickness varies only with the changes in shoe size - friction lighting material can only be riveted to the brake shoe - the secondary shoe usually has the smaller brake linings - the primary shoe is the first shoe from the wheel cylinder in the direction of rotation

Answer 51

the primary shoe is the first shoe from the wheel cylinder in the direction of rotation

Question 52

When should brake shoes be replaced?

Answer 52

When lightnings are worn to within 1.59 mm of a rivet head

Question 53

In the unapplied position, how are the drum brake shoes held against the anchor pin

Answer 53

Return Springs

Question 54

What are duo-servo drum brakes also known as

Answer 54

Self energizing brakes

Question 55

What does the star wheel automatic adjuster change on drum brakes?

Answer 55

The adjustment mechanism is located on the secondary shoe

Question 56

What is the function of the wheel cylinder?

Answer 56

To convert hydraulic pressure to mechanical force against the brake shoe

Question 57

How should backing plates, struts, levers, and other metal brake parts be cleaned?

Answer 57

Wet cleaned using water or a water base solution

Question 58

What can break dust and dirt between the lining and the drum cause?

Answer 58

Score drum surface

Question 59

What does the diameter stamped on the brake drum refer to?

Answer 59

The maximum (discard) diameter

Question 60

What can cause a drum to become convex shaped?

Answer 60

Overheating the drum

Question 61

What park brake component ensures that both drum assemblies receive the same application force

Answer 61

The equalizer

Question 62

What is the maximum brake drum out of roundness allowed for machining or drum replacement is required

Answer 62

0.006” of an inch or 0.150 mm

Question 63

Define self energizing

Answer 63

The wedging action combined with the applied brake force creates a multiplied brake force

Question 64

What are the 2 styles of drum brakes

Answer 64

Servo Nonservo (leading - trailing)

Question 65

When should drum brake hardware be replaced

Answer 65

When damaged or new shoes are installed.

Question 66

What is a pressure differential valve

Answer 66

If either of the circuit looses pressure it moves a valve to complete an electric circuit, which activates a warning light / signal

Question 67

What is a metering valve

Answer 67

Utilized on vehicles with disk and drum brakes. The valve delays application of the front brakes until the drum has sufficient pressure

Question 68

What is a proportioning valve

Answer 68

It regulates rear drum brake pressure during hard/ moderate applications to prevent rear wheels from locking up Drum brakes for all wheels typically don’t have a proportioning valve

Question 69

What is pedal fade

Answer 69

Brake fluid leaking past the primary cup seal into the spool area

Question 70

A seized piston generally pulls the vehicle which way

Answer 70

Opposite side when brakes are applied

Question 71

Test to determine seized piston or caliper

Answer 71

Lift vehicle, apply brakes, spin wheels - any rotation is an indication of a seized piston.

Question 72

Why is armoured tubing replaced with the same type

Answer 72

To maintain safety standards

Question 73

An advantage of using a tandem master cylinder is that

Answer 73

A fault in one circuit will not cause a complete failure

Question 74

In the release position, the master cylinder cups are located

Answer 74

Between the vent and replenishing ports

Question 75

How can a cracked flex hose be serviced

Answer 75

Replace

Question 76

Why is it important that there is no residual pressure in the brake system when in the unapplied position

Answer 76

To make sure that the front brakes do not drain or slightly stay applied

Question 77

During a normal stop, which of the following valves is the first to operate

Answer 77

Metering valve

Question 78

Wheel cylinders are capable of delivering what kind of force when compared to calipers

Answer 78

Less force than a caliper