Michigan State Brakes Certification Practice Exam

When a mechanic hears a squeaking noise at the rear of a vehicle while applying the brake, what is a likely cause?

1. Glazed brake pads

2. Worn brake shoes

3. Dry backing plate contact surfaces

4. A malfunctioning brake caliper

The correct answer is: Dry backing plate contact surfaces

The occurrence of a squeaking noise at the rear of a vehicle while applying the brake is often indicative of issues related to the backing plate contact surfaces. When these surfaces become dry, they can cause friction that generates noise every time the brakes are engaged. In brake systems, backing plates serve as a point of contact for brake components, and if they lack proper lubrication, they can create squeaking or squealing noises when the brakes are applied. This can happen due to accumulation of dirt, rust, or simply lack of maintenance that leads to insufficient lubrication. Properly maintaining these surfaces can reduce noise and promote smoother operation of the braking system. While glazed brake pads, worn brake shoes, and a malfunctioning brake caliper can also lead to performance issues, they typically manifest in different ways. Glazed brake pads can cause a hard, non-communicative feel in braking along with a high-pitched squeal, worn brake shoes may result in grinding noises, and a malfunctioning brake caliper could lead to uneven brake wear or a pulling sensation rather than a consistent squeak. Thus, in the context of the squeaking noise specifically at the rear, the dry backing plate contact surfaces are the most likely cause.