ASE G1 Auto Maintenance and Light RepairBrakesMedium
A customer complains of excessive brake dust on their front wheels after installing new brake pads and rotors. The technician confirms the brake dust is black and sticky. Which of the following is the MOST likely cause?
- AThe brake calipers are sticking.
- BThe brake pads are worn out prematurely.
- CThe new pads are a semi-metallic formulation.
- DThe rotors are glazed.
Show answer & explanationAnswer & explanation
Correct answer: C. The new pads are a semi-metallic formulation.
Semi-metallic brake pads are known for their excellent stopping power and durability but often produce more black, sticky brake dust compared to ceramic or organic pads. This is a normal characteristic of their friction material composition.
Why the other options are wrong
- A. Sticking calipers would cause excessive heat, pulling, or premature wear, not just excessive dust as a primary symptom after new parts.
- B. Worn-out pads would cause reduced braking and grinding, not necessarily excessive dust shortly after installation.
- D. Glazed rotors would cause reduced braking effectiveness and possibly noise, but not directly lead to excessive black, sticky dust from new pads.
Semi-Metallic Brake Pads
Brake pads made from a mix of metallic fibers (steel, copper, iron) and organic materials, known for their performance and durability.
- Offer good stopping power and fade resistance.
- Typically produce more brake dust (often black) than ceramic pads.
- Can be noisier and harder on rotors than other types.
Memory trick: Semi-metallic pads are strong but leave a dusty trail.