Chapter 4 Flashcards
A fast-fill or quick take-up master cylinder is identified by the dual bore design that creates a _______________ or _______________ _______________ of the casting.
Bulged or steeped out
DOT 3 and DOT 4 fluids are polyalkylene- glycol-ether mixtures, called _______________ for short.
poly-glycol
Because both DOT 3 and DOT 4 fluids _______________ _______________ from the air, always keep containers tightly capped.
absorbs water
Silicone fluid _______________ slightly under pressure, which can cause a slightly spongy brake pedal feel.
compresses
Polyglycol fluids have a very _______________ shelf life.
short
The _______________ -to- _______________ hydraulic split system is the oldest split system.
front to back
Most late-model cars have a _______________ split hydraulic system.
diagonal
The master cylinder has two main parts: a _______________ and a _______________.
reservoir and a body/cylinder
All master cylinder caps or covers are vented to prevent a _______________ _______________ as the fluid level drops in the reservoir.
Vacuum Lock
The piston assembly at the rear of the cylinder is the _______________ piston, and the one at the front of the cylinder is the _______________ piston.
primary, secondary
Technician A says the master cylinder changes the driver’s mechanical force on the pedal to hydraulic pressure. Technician B says this hydraulic pressure is changed back to mechanical force at the wheel brakes. Who is correct?
c. Both
Technician A says choosing the right fluid for a specific vehicle is based on the simple idea that if DOT 3 is good, DOT 4 must be better, and DOT 5 better still. Technician B says most vehicle man- ufacturers recommend DOT 4. Who is correct?
D. None
Technician A says the dry boiling point of brake fluid is the minimum boiling point of new, uncon- taminated fluid. Technician B says polyglycol flu- ids are hygroscopic, which means that they do not absorb water vapor from the air. Who is correct?
A only
Technician A says a high-temperature boiling point is the only requirement that brake fluid must meet. Technician B says brake fluid also must resist freezing and evaporation and must pass specific viscosity tests at low temperatures. Who is correct?
B ONly
Technician A says DOT 5 Silicone fluid does not
absorb water. Technician B says DOT 5 silicone fluid is a purple fluid with a very high boiling point, is noncorrosive to hydraulic system com- ponents, and does not damage paint as does ordi- nary fluid. Who is correct?
C Both
Technician A says synthetic DOT 3/4 and DOT 5.1 are compatible with DOT 3 and DOT 4 fluids and can be mixed with them. Technician B says DOT 5.1 is based on polyglycol chemistry. Who is correct?
d. neither a nor b
Technician A says if water or other contaminants are found in the brake system and master cylinder piston seals have been damaged, it is okay to flush the system with clean fluid and put it back in ser- vice. Technician B says replace all sealing parts in the system, including the brake hoses and any valves or switches with rubber seals. Who is correct?
B only
Brake pedal linkage free play at the master cylin- der is usually very slight generally about:
A. 1/16 inch (1.5 mm to 20 mm)
B. 1/4 inch (6.25mm)
C. 1/8 inch (3.17 mm)
D. 5/16 inch (7.9mm)
A 1/16 inch
Technician A says most modern vehicles have a diagonally split hydraulic system. Technician
B says the advantage of this system is that if one system fails, the vehicle will have less than
50 percent of the braking action from one front and one rear brake. Who is correct?
C. Both
Technician A says each master cylinder piston works with a rubber cup seal that fits in front of the piston head. Technician B says the cup has rigid lips that fit against the cylinder walls to allow fluid leakage around the seal. Who is correct?
A. A only
- Explain why DOT 5 brake fluid is not recom- mended by any manufacturer.
Contains silicone compresses slightly under pressure which can cause spongy feel. Also attracts more air making bleeding harder. Other probles with seal wear and speration in system and not recommended in a abs
xplain why the boiling point of brake fluid is important.
Brake fluid shouldn’t be allowed to boil to increase pressure
- Explain why it is not a good idea to mix DOT 5 fluids with DOT 3 and DOT 4.
Has a lower specific gravity and if mixed they do not blend.
- Describe a sure sign of brake fluid contamination with mineral oil.
seals will detriorate
