Brake Systems Flashcards

What is the function of the brake caliper?

Answer: To house the brake piston(s) and clamp the brake pads against the rotor when hydraulic pressure is applied

The brake caliper straddles the brake rotor and contains one or more hydraulic pistons. When pressure is applied, the piston(s) push the brake pads against the rotor, creating friction to slow the wheel.

What is the purpose of the vacuum brake booster?

Answer: To multiply the driver's brake pedal force using engine vacuum to reduce pedal effort

The vacuum booster uses engine intake manifold vacuum on one side of a large diaphragm and atmospheric pressure on the other to multiply the driver's pedal force, typically by a factor of 3-4, reducing the effort needed to brake.

What is the correct procedure for bleeding a brake system?

Answer: Start with the wheel farthest from the master cylinder and work toward the closest

The standard bleeding sequence starts at the wheel farthest from the master cylinder (usually right rear) and works toward the closest (usually left front). This ensures air is progressively pushed out of the longest lines first.

What causes a brake caliper to stick or seize?

Answer: Corroded caliper piston, damaged piston seal, or corroded slide pins preventing proper movement

Caliper sticking is caused by corrosion on the piston bore, a swollen or damaged piston seal, or corroded/dry caliper slide pins (on floating calipers) that prevent the caliper from retracting or sliding freely.

What is the purpose of DOT brake fluid ratings (DOT 3, DOT 4, DOT 5.1)?

Answer: They specify minimum dry and wet boiling points to ensure the fluid can withstand heat generated during braking

DOT ratings specify minimum boiling points — both dry (new fluid) and wet (moisture-contaminated fluid). Higher DOT numbers indicate higher boiling points, providing more resistance to vapour lock during hard braking.

What does the ABS warning light illuminating during normal driving indicate?

Answer: A fault has been detected in the ABS system and antilock function is disabled

The ABS warning light indicates the ABS control module has detected a fault and has disabled antilock braking. The base brake system still functions normally, but the wheels can lock during hard braking.