Why Rear Mounted Disk Brakes Replaced Rear Drum Brakes in Cars

For a long time, rear drum brakes were the standard setup for many vehicles. However, with the advent of more efficient and reliable alternatives, rear disk brakes have become increasingly popular. This shift is primarily due to the superior performance and durability of disk brakes compared to their drum counterparts.

Why Disk Brakes Are Superior

The transition from rear drum brakes to disk brakes is mainly driven by the fundamental differences in their operational mechanisms and performance characteristics. Disk brakes, as their name suggests, consist of a brake disk that is clamped by brake pads, providing a direct electric field that produces heat and friction, resulting in rapid and efficient deceleration. In contrast, drum brakes use a drum that is squeezed by pads, which then slow down the vehicle.

Water Resistance

One of the most significant advantages of disk brakes is their water resistance. Unlike drum brakes, which can suffer significant performance degradation when exposed to water, disk brakes continue to function effectively even when wet. This is particularly crucial in wet or rainy conditions, when the reliability of the braking system is of utmost importance. The water resistance of disk brakes makes them a preferred choice for safety-conscious drivers and vehicle manufacturers alike.

Brake Fade

Another critical factor in the evolution of rear brakes is the issue of brake fade. Disk brakes do not suffer from brake fade, which is a significant drawback of drum brakes. Brake fade occurs when the brakes lose their effectiveness due to overheating. Drum brakes, especially when used in conjunction with front-disc/rear-drum systems, can experience severe fade, leading to reduced braking performance during successive stops or in long descents. Disk brakes, being more centralized and better at dissipating heat, eliminate this issue, ensuring consistent and reliable braking performance.

Repair and Maintenance

While some might argue that drum brakes are less complex and potentially easier to maintain, the advantages of disk brakes in terms of performance and durability far outweigh these considerations. Disk brakes are generally more robust and less prone to wear and tear, leading to fewer repairs and longer lifespans. This is particularly important for rear brakes, which are subject to significant wear due to the weight distribution and the natural tendency of vehicles to shift their center of gravity during braking.

Handbrake Considerations

One area where disk brakes can fall short is in handbrake duty. While conventional disk brakes excel in braking efficiency, they experience a slight contraction as they cool down, which can affect the effectiveness of the handbrake. This is because the brakes sometimes retain residual heat, leading to a slight change in the brake pad and rotor dimensions. In contrast, drum brakes have the advantage of maintaining more consistent dimensions, even after repeated activation and cooling. Therefore, for vehicles that heavily rely on the handbrake, such as those used for high-speed descents or emergency stops, drum brakes might still be the preferred option.

Conclusion

The shift from rear drum brakes to disk brakes in vehicles is a testament to the advancements in automotive technology. While disk brakes may have minor drawbacks in handbrake performance, their superior water resistance, lack of brake fade, and overall durability make them the preferred choice for modern vehicles. As technology continues to evolve, it is likely that we will see further improvements in brake systems, ensuring safer and more reliable driving experiences for motorists everywhere.

Keywords

Keywords: rear disk brakes, drum brakes, brake performance