Automobile & Light Truck Certification Test A5 BrakesDisc Brake Diagnosis and RepairMedium
A customer complains that their vehicle's parking brake does not hold the vehicle securely on an incline. The vehicle is equipped with a rear disc brake system with an integrated drum-style parking brake (hat-type). What is the MOST likely cause?
- AA seized rear disc brake caliper piston.
- BWorn or glazed rear disc brake pads.
- CImproperly adjusted parking brake shoes or stretched parking brake cable.
- DAir in the hydraulic brake system.
Show answer & explanationAnswer & explanation
Correct answer: C. Improperly adjusted parking brake shoes or stretched parking brake cable.
A hat-type parking brake uses small brake shoes inside the rotor 'hat' section, independent of the disc brake pads and caliper. If the parking brake doesn't hold, it's typically due to worn shoes, improper adjustment, or a stretched cable not allowing sufficient shoe expansion.
Why the other options are wrong
- A. A seized caliper piston affects the hydraulic service brake, not the mechanical parking brake.
- B. Worn disc pads affect the service brakes, not the independent drum-style parking brake.
- D. Air in the hydraulic system affects the service brake pedal feel and stopping power, not the mechanical parking brake.
Hat-Type Parking Brake
A parking brake system where small drum brake shoes are housed within the 'hat' section of a disc brake rotor.
- Operates independently of the hydraulic service brakes.
- Activated mechanically by a cable.
- Requires periodic adjustment of the shoes.
Memory trick: Park it right, hold it tight.