Automobile & Light Truck Certification Test A5 BrakesDisc Brake Diagnosis and RepairEasy
A technician is inspecting a vehicle's disc brake system. They notice that the brake pads on one side of a floating caliper are significantly more worn than the pads on the other side. Which of the following is the MOST likely cause of this condition?
- AExcessive rotor runout.
- BSeized caliper guide pins.
- CAir in the hydraulic system.
- DA faulty brake master cylinder.
Show answer & explanationAnswer & explanation
Correct answer: B. Seized caliper guide pins.
Seized caliper guide pins prevent the floating caliper from moving freely, causing uneven pressure application to the brake pads. This results in one pad wearing significantly more than the other.
Why the other options are wrong
- A. Excessive rotor runout primarily causes brake pulsation and potentially some uneven wear, but seized guide pins are a more direct cause of significantly uneven wear across a single caliper's pads.
- C. Air in the hydraulic system causes a spongy pedal and reduced braking force, but not typically uneven pad wear within a single caliper.
- D. A faulty master cylinder would typically affect braking on all wheels or a whole circuit, not just one side of a single caliper.
Floating Caliper Uneven Wear
Uneven brake pad wear in a floating caliper system, where one pad wears more than the other, often indicates a problem with the caliper's ability to slide freely.
- Floating calipers rely on free movement to apply even pressure.
- Guide pins allow the caliper to slide.
- Seized pins restrict movement, leading to uneven wear.
Memory trick: Freedom of Slide is Key for Even Wear.