Which of the following could cause disc brake squeal?

• A. Grease on the linings
• B. Worn brake pads
• C. Air in the brake fluid
• D. Overheating of brake components

Answer: (A)

Grease on the linings can indeed cause disc brake squeal because contaminants like grease can interfere with the proper contact between the brake pads and the disc. When the pads are contaminated, they can create a situation where friction is not effectively managed, leading to vibrations that produce a squealing sound when braking. This noise often results from the friction material not being able to smoothly grip the disc surface due to the presence of grease.

Worn brake pads and overheating of brake components can also contribute to noise issues, but the specific link to squeal is often more associated with contamination and improper surface contact as seen with grease. Air in the brake fluid typically causes issues related to consistent braking performance and pedal feel rather than producing a squealing sound. Understanding these dynamics will help you focus on the maintenance practices required to avoid such issues in brake systems.