A customer complains of a grinding noise coming from the rear brakes during light to moderate braking. Upon inspection, the technician finds that the rear brake pads are severely worn, and the backing plates are scraping against the rotors. The vehicle is equipped with a hat-type parking brake system. What is the MOST likely reason the customer did not notice this issue earlier with the parking brake?
- AThe parking brake cable is improperly adjusted.
- BThe parking brake shoes are also severely worn.
- CThe rear brake caliper pistons are seized.
- DThe parking brake system operates independently of the service brakes.
Show answer & explanationAnswer & explanation
Correct answer: D. The parking brake system operates independently of the service brakes.
A hat-type parking brake system uses small drum brake shoes located inside the 'hat' portion of the disc brake rotor. This system is completely independent of the hydraulic service brake pads. Therefore, even if the service brake pads are completely worn, the parking brake would still function, and its operation would not provide an indication of the service brake pad wear.
Why the other options are wrong
- A. Improper cable adjustment would affect parking brake holding power, but not its ability to indicate service brake pad wear.
- B. While possible, it's not the primary reason the parking brake wouldn't alert to service brake pad wear, as they are separate systems.
- C. Seized caliper pistons would cause uneven wear or dragging, but the parking brake's independence is the key reason it wouldn't act as a warning.
Hat-Type Parking Brake Independence
Hat-type parking brake systems utilize separate drum brake shoes within the rotor's 'hat' and operate independently of the hydraulic service disc brakes, meaning their performance does not reflect the condition of the service pads.
- Separate shoes inside the rotor's hat.
- Mechanically actuated, not hydraulic.
- Does not indicate service brake condition.
Memory trick: Parking brakes, service brakes, separate ways they take.