Drum Brakes vs. Disc Brakes

60s muscle carAmerica’s obsession helped propel the advancement of brake systems.
The wild popularity of performance and muscle cars in the 1950s pushed automotive manufacturers into a competition to one up each other. Instead of luxury, manufacturers were trying to build rides that could reach high speeds and perform under the toughest conditions. The result was an improvement in suspension, fuel system technology, and BRAKING.

Manufacturers improved braking by introducing carbon fiber, sintered metal, and lightweight steel. But, the most important revolution came when manufacturers switched from drum brakes to disc brakes in the early 1970s. Today, all automobiles sold in the United States are required to include disc brakes, but many manufacturers still include both disc and drum brakes.

Too Hot to Handle

Disc brakes and drum brakes both revolve around two principles, friction and heat. Naturally, brakes are designed to slow down a vehicle’s wheels by rubbing against them and creating friction. When the friction occurs, the brakes are essentially absorbing the energy of the wheels. The energy created by the friction is turned into heat, and the effectiveness of brakes depends on its ability to absorb and release this heat. This principle is the source of the main difference between drum brakes and disc brakes.

drum brakesDrum brakes trap heat inside causing them to be less effective.
Drum Brakes

Before disc brakes, early automobiles used drum brake systems for all four wheels. All of the components of this style brake system were contained within a drum (hence the name) that rotated along with the wheel. The most important component within the drum was a shoe that would push against the wall of the drum and slow the wheel down anytime the driver pressed on the brake pedals.

The major problem with this design was that the all-encompassing nature of the drum would trap in too much heat. Because the most important aspect of a brake system is to absorb energy and release it, the drum brake proved to be ineffective because it just couldn’t release the energy.

This wasn’t a problem in most instances because brakes are only tapped every so often, but when faced with more difficult situations like going downhill, the drum brake proved to be no good because it could only absorb a certain amount of heat before losing its capabilities.

truck 5Better braking means better handling around sharp corners.

Disc Brakes

Disc brakes are designed to slow vehicles down by using a rotor, a caliper, and a set of brake pads. When a driver steps on the brake pedals, the three work in unison to clamp the brake pads against the side of the wheels. Unlike the drum design, disc brakes are out in the open, which allows it to release heat at a far greater capacity.

Today, most manufacturers use disc brakes for their front wheels and use drum brakes for the back wheels. This is ideal for many car companies because they can still be effective while cutting costs. Because 70 percent of a vehicle’s braking power is reliant on the front wheels, disc braking can be used up front and nothing will be lost. Meanwhile, drum brakes can be used on the back wheels and auto manufacturers can save money.

Even though that may sound cheap of manufacturers, the truth is almost no performance is lost because drum brakes that are made today are incredibly capable, especially when they are only needed to carry 30 percent of the load.

In the past 50 years, brake systems have come a long way. Understanding your truck or car’s brakes will help you to be safer out on the roads and help you to understand your vehicle even further.

By: Tim Snyder
Posted on October 1st, 2013
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