Disc Brake Systems

Question 1

List 5 advantages and 2 disadvantages of disc brake systems versus drum brake systems

Answer 1

advantages

1) resist fade
2) self-adjusting
3) self-cleaning
4) simpler (less parts)
5) even, predictable application

disadvantages

1) not self-energizing
2) noisy

Question 2

What are the 2 primary functions of the disc or rotor?

Answer 2

1) provides a friction surface

2) dissipates heat and acts as a heat sink

Question 3

The condition that could result if discs with directional louvres were installed in the wrong side of the vehicle is called? _____________ What should you do to avoid this from occurring?

Answer 3

brake fade - Mark the discs when removing them

Question 4

A disc is marked “minimum thickness 29.60 mm.” Manufacturer specifications say that 0.6 mm is to be left for wear. What is the thinnest dimension you can machine the disc to?

Answer 4

30.20 mm

Question 5

What is the purpose of the shim used between some pads and the caliper piston?

Answer 5

Shims isolate the pad from the caliper piston to prevent noise

Question 6

What must be done to prevent damage to the flex hose when the caliper is removed from its mount, but not disconnected from the hydraulic system?

Answer 6

Support the caliper

Question 7

Why should you open the bleeder screw when forcing the piston back into its bore?

Answer 7

Prevents forcing contaminants back through the hydraulics.

Question 8

Explain why self-adjusters for the parking brake are generally not used in drum-in-hat style parking brake systems, but are required for integral calipers.

Answer 8

Drum-in-hat style systems use separate linings that should not wear. Integral style calipers use the same friction members as the service brakes and will wear with use.

Question 9

Linings used in drum-in-hat parking brakes are likely to have a ___________ coefficient of friction than linings for the service brake. Why?

Answer 9

higher - their function is to hold a stopped vehicle not to stop a moving vehicle

Question 10

Why might a manufacturer specify that the drum portion of a drum-in-hat disc must not be machined?

Answer 10

Drum portion is structurally essential and very thin; machining it may weaken it.

Question 11

Which of the following methods should be used to retract the piston on an integral style of rear caliper?

a) press it in with a c-clamp
b) turn it in with a spanner
c) use the special tool provided by the manufacturer
d) any of the above, depending on the style of caliper used

Answer 11

d) any of the above depending on the style of caliper used

Question 12

What are the 2 most common types of brake pad wear indicators used on today’s vehicles?

Answer 12

1) metal squealer

2) electric contact or sensor

Question 13

When installing brake pads, what properties should the brake lube you use have?

Answer 13

a) silicone based

b) withstand high heat

Question 14

On a vehicle equipped with electric park brakes, the park brake will not apply if the vehicle is in motion

a) true
b) false

Answer 14

b) false

Question 15

Name the two types of brake pad wear indicators.

Answer 15

“squealer” and electrical contact

Question 16

Generally the minimum lining thickness for a bonded brake pad is….

Answer 16

3mm

Question 17

Glazed brake pads is a result of what?

Answer 17

Overheating

Question 18

True or False. Pads that have been contaminated with oil can be sanded down or washed with brake cleaner to make re-usable.

Answer 18

False

Question 19

Brake rotor “run-out” is measured using what measuring instrument?

Answer 19

Dial indicator

Question 20

Variations in rotor thickness is referred to as…..

Answer 20

Parallelism

Question 21

What are the two types of parking brake used on disc brake systems?

Answer 21

Drum-in-hat , and Integral

Question 22

16. How many rotor measurements must be taken to determine parallelism? 
A.A minimum of 8. 
B.6 at 45º from one another. 
C.4 at 90º from one another.
D.2 at 180º from one another

Answer 22

A. 8 locations

8 at 45deg apart