Brake Systems and Safety Inspection Flashcards

To test a vacuum brake booster, the technician pumps the pedal with the engine off, holds steady pressure, and starts the engine. What should happen?

Answer: The pedal should drop slightly

When the engine starts and vacuum returns, a working booster adds force and the pedal drops slightly under the driver's foot.

A customer complains of a hard brake pedal that needs high effort to stop. What is the most likely cause?

Answer: Low or no vacuum to the brake booster

Without enough booster vacuum, the driver has to supply all the force, which gives a hard pedal.

What supplies the power assist on a Hydro-Boost brake system?

Answer: The power steering pump

Hydro-Boost uses hydraulic pressure from the power steering pump to assist braking.

Which repair most commonly reduces disc brake squeal?

Answer: Installing anti-noise shims or damping compound on the pad backing plates

Shims and damping compounds absorb the high-frequency vibration between the pad and caliper that causes squeal.

How is the caliper piston usually retracted on a rear disc brake with an integral parking brake?

Answer: Rotate (screw) it in with a piston retraction tool

Integral parking brake calipers have a threaded mechanism, so the piston must be rotated in, not forced straight back.

Brake pads have a shiny, glazed surface. What usually causes this?

Answer: Overheating from hard or prolonged braking

Too much heat hardens and glazes the friction surface, which lowers the coefficient of friction.

During a long downhill descent, the brakes lose effectiveness even though pedal travel stays normal. This is called:

Answer: Brake fade

Brake fade happens when friction materials overheat and lose grip, so stopping power drops.