What problem may arise from using a residual check valve in a disc brake master cylinder?

• A. Increased pedal travel
• B. Contaminated brake fluid
• C. Increased brake pad wear
• D. Reduced stopping power

Answer: (C)

Using a residual check valve in a disc brake master cylinder can lead to increased brake pad wear. This is primarily due to the valve's function of maintaining a slight pressure in the brake lines even when the brake pedal is not engaged. In disc brake systems, this pressure can prevent the brake pads from fully retracting away from the rotors after braking. As a result, the pads remain in contact with the rotors, leading to continuous friction and heat generation, which can accelerate wear on the brake pads.

Additionally, consistent contact can also contribute to potential overheating, which further compromises pad longevity and performance. It's essential to ensure that the appropriate valve is used in accordance with the braking system design, as disc systems typically do not require a residual pressure. This understanding helps diagnose issues related to brake performance and wear more effectively.