Advantages of Drum Brakes in Vehicles

Drum brakes have been a standard feature in many vehicles for decades. While many modern vehicles favor disc brakes for their superior stopping power and heat dissipation, drum brakes still offer several advantages. This article will explore these benefits and provide insights from personal experiences.

Self-Servo Action and Superior Parking Brake

One of the key advantages of drum brakes is their self-servo action. This feature requires less brake pedal pressure, making it easier to operate. Additionally, drum brakes provide a superior parking brake due to their mechanical design. The self-servo action means that the force exerted by the brake shoes on the rotor is amplified, resulting in increased stopping power with less effort. This is particularly beneficial for vehicles like the modified USMC CJ2 variant originally featured in the author's experience.

Longevity and Serviceability

Another significant advantage of drum brakes is their longevity. Brake shoes, which are a key component of drum brakes, tend to last longer than brake pads in most situations. The simple design of drum brakes also makes them easier to inspect and maintain. When the author had their 1999 Mitsubishi Eclipse GST restored to a daily driver, replacing the rear drum brakes with rear discs improved serviceability and visual appeal. However, drum brakes were more than adequate for most daily driving conditions, as evidenced by their ability to handle multiple hard braking scenarios without significant performance degradation.

Servo Effect and Swept Area

The swept area of the brake shoes to drum surface ratio is another factor that enhances drum brake performance. The larger surface area of the drum provides a greater swept area for the brake lining, resulting in a better braking effect. The servo effect further amplifies the force applied, making drum brakes particularly effective in scenarios where less pedal pressure is required. In the author's experience, this effect was noticeable in the stopped distance of the car during a series of 100-to-0 braking tests.

Heat Dissipation and Failure

While drum brakes offer several advantages, they are not without their drawbacks, especially when subjected to high heat and hard braking. As the author observed, the rear drum brakes began to heat up and fade after multiple consecutive braking cycles. This is primarily due to the drum's inability to dissipate heat as efficiently as disc brakes. In vehicles like the 2008–2015 Dodge Charger, the base model's small rotors and pads may seem inadequate, but they are still perfectly adequate for the power-to-weight ratio of the car.

Parking Brake Effectiveness

In addition to their superior parking brake, drum brakes also offer another advantage. Many vehicles have a cable-operated parking or hand brake that actuates the rear drum shoes mechanically. Because of the larger size of the drum, the parking brake tends to be more effective. This mechanical advantage can be crucial in preventing the tire from spinning when the car is parked or in low-speed scenarios.

In conclusion, while modern vehicles often favor disc brakes for their superior stopping power and heat dissipation, drum brakes still offer several notable advantages. They are more durable, easier to inspect and maintain, and provide a superior parking brake. Despite these benefits, drum brakes may not be ideal for high-performance scenarios or vehicles that are frequently subjected to severe driving conditions.