What could cause the front brakes on a car with disc/drum brakes to grab quickly when light pedal pressure is applied?

• A. Leaking brake line
• B. Faulty brake booster
• C. Bad metering valve
• D. Worn brake pads

Answer: (C)

The correct answer highlights the importance of the metering valve's function in a disc/drum brake system. The metering valve is responsible for controlling the pressure to the drum brakes, ensuring that they engage at the correct time relative to the disc brakes. If the metering valve is faulty, it may not regulate pressure properly, which can lead to uneven braking actions. Consequently, when light pedal pressure is applied, the front brakes—being disc brakes—could engage too quickly or sharply compared to the rear drum brakes, leading to a grabbing sensation.

In contrast, a leaking brake line would typically cause a drop in brake fluid pressure, leading to a spongy brake pedal or reduced braking efficiency. A faulty brake booster affects the brake pedal's assist, which can lead to increased pedal effort rather than grabbing. Worn brake pads may reduce braking efficiency overall but wouldn't specifically cause the brakes to grab sharply at light pressure; instead, they would likely result in reduced stopping power or longer stopping distances.

Understanding the specific function and impact of the metering valve helps clarify why this answer is correct in the context of brake system dynamics.