A technician is performing a brake inspection and notices that the brake pads on the inner side of a fixed caliper are significantly more worn than the outer pads. Which of the following is the MOST likely cause?
- AA collapsed brake hose restricting fluid flow to one piston.
- BA seized caliper piston on the inner side.
- CExcessive rotor runout causing uneven contact.
- DAir trapped in the hydraulic system.
Show answer & explanationAnswer & explanation
Correct answer: B. A seized caliper piston on the inner side.
In a fixed caliper, both inner and outer pads are actuated by individual pistons. If the inner pad is significantly more worn, it indicates that the inner piston is applying more force or not retracting properly, which points to a seized or sticking piston on that side. A collapsed hose would affect fluid flow to one whole side (if it's a dual-piston caliper on both sides) or multiple pistons, but a single seized piston is a more direct cause of uneven wear on just one pad within a fixed caliper.
Why the other options are wrong
- A. A collapsed hose would restrict fluid flow, potentially causing less braking force on that side, leading to less wear, or affecting multiple pistons if present.
- C. Excessive rotor runout typically causes pulsation and can lead to uneven wear across both pads, but not usually a significant difference between inner and outer pads on a fixed caliper.
- D. Air in the system would cause a spongy pedal and reduced overall braking force, not typically uneven wear between inner and outer pads in a fixed caliper.
Fixed Caliper Uneven Wear
Uneven brake pad wear in a fixed caliper system, especially between inner and outer pads, often indicates a problem with individual caliper pistons, such as seizing or sticking.
- Fixed calipers have multiple pistons on both sides.
- Each piston independently actuates a pad.
- Piston issues directly cause uneven pad wear.
Memory trick: Fixed caliper, piston trouble, wear unequal, cause the rumble.