Disc brakes vs. drum brakes: what do I have?

If you're looking to get your brakes changed, it's important to first understand what kind of brakes you have: disc or drum brakes. You will need to know this information when ordering new parts. 

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What kind of brakes are on my car? 

Nowadays, the majority of new vehicles have disc brakes in the front and drum brakes in the back. It's not uncommon to see disc brakes on all four wheels too. But only very very old vehicles will have drum brakes all around - the switch to disc brakes came in the s. 

How to tell whether your brakes are drum or disc

To double-check, look through one of the holes in the top of your front wheel. If you see a shiny smooth metal surface, that is your disc rotor. However, if you see a rusty and not smooth round surface, that's your brake drum. Some rotors will have light rust specklings. 

Another way to check is to look at the backside of the wheel - a disc brake will have a rubber hose going to the brake calliper, whereas a drum brake will have a metal tube.

Drum brakes 

In the early days of cars, automotive manufacturers installed drum brakes at every wheel. They are called that because all the braking components are contained in a round drum (surprising!) that rotates with the wheel. When you brake, the shoes inside the drum press on it, slowing down the wheel. The problem with these brakes is they often fade on steep hills or during aggressive braking because the drum cannot contain the heat buildup created. This design flaw and performance failures that came from it led to drum brakes being deemed unsafe for these specific driving conditions. 

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Disc brakes

Back then, manufacturers discovered that car racers enjoyed a better performance in competitions with a new type of car brake: disc brakes. In this design, the disc (or the rotor) is exposed to outside air all the time and braking is done with the caliper and brake pads as opposed to shoes in the brake drum. The disc brake has a chance to actually cool down compared to the drum which traps in the heat. This new at-the-time design allowed heat to escape which drastically improved braking performance. It was decided then to make the switch to disc brakes in the front since most cars became front-wheel drive and the majority of braking power (60-90%) comes from the front wheels. Most new vehicles have a front disc and rear drum brake set-up which is perfectly safe because both types of brakes have been further improved since the s. 

Types of brakes on your car

While to stop or slow down, you may have disc or drum brakes on your vehicle, there are actually even more brakes to be aware of! The other type is an emergency brake, also called a parking brake, which is designed to bypass the normal braking system. These use levers or cables to stop the car in case the regular brakes malfunction. These usually go to the rear of the car and stop it from there. Another type of brake on your vehicle may be Anti-lock Braking System (ABS) if you have a newer model. 

Drum Brakes vs Disc Brakes

Design

• Drum Brakes: Enclosed design with brake shoes inside a drum.
• Disc Brakes: Open design with brake pads gripping a rotor.

Heat Dissipation

• Drum Brakes: Less efficient heat dissipation.
• Disc Brakes: More efficient heat dissipation.

Cooling

• Drum Brakes: Limited cooling due to enclosed design.
• Disc Brakes: Better cooling due to open design.

Brake Fade

• Drum Brakes: More susceptible to brake fade.
• Disc Brakes: Less susceptible to brake fade.

Stopping Distances

• Drum Brakes: Generally longer stopping distances.
• Disc Brakes: Shorter stopping distances.

Maintenance

• Drum Brakes: Require periodic adjustments for optimal performance.
• Disc Brakes: Require less maintenance and adjustments.

Weight

• Drum Brakes: Heavier compared to disc brakes.
• Disc Brakes: Lighter compared to drum brakes.

Performance in Wet

• Drum Brakes: Slightly less effective in wet conditions.
• Disc Brakes: More effective in wet conditions.

Noise

• Drum Brakes: Produce less noise during braking.
• Disc Brakes: Can produce more noise during braking.

Corrosion

• Drum Brakes: Generally less susceptible to corrosion.
• Disc Brakes: More susceptible to corrosion in rotor and caliper.

Brake Dust

• Drum Brakes: Generate less brake dust.
• Disc Brakes: Generate more brake dust.

Complex Components

• Drum Brakes: Simpler design with fewer components.
• Disc Brakes: More complex with calipers, pistons, and rotors.

Price

• Drum Brakes: Typically more affordable.
• Disc Brakes: Generally more expensive.

Parking Brake

• Drum Brakes: Integrated parking brake mechanism.
• Disc Brakes: Parking brake functionality may vary.

Advantages of Drum Brakes

1. Durability: Drum brakes are known for their durability, making them suitable for heavy-duty applications and prolonged usage.
2. Suitability for Rear Wheels: Due to their design and construction, drum brakes are often preferred for rear wheel applications, providing reliable braking performance.
3. Ease of Installation: Installing drum brakes is relatively straightforward, requiring fewer components and less complexity compared to disc brakes.

Drawbacks of Drum Brakes

1. Heat Retention: Drum brakes tend to retain more heat during prolonged braking, leading to issues such as brake fade and reduced braking performance.
2. Limited Cooling: The enclosed design of drum brakes restricts airflow, resulting in limited cooling capacity and potential overheating.
3. Maintenance Complexity: Drum brakes require more involved maintenance, including periodic adjustments and potential repairs, which can be time-consuming and costly.

Advantages of Disc Brakes

1. Superior Performance: Disc brakes offer superior braking performance, shorter stopping distances, and improved responsiveness, enhancing overall safety.
2. Efficient Heat Dissipation: Disc brakes dissipate heat more efficiently, reducing the risk of brake fade and maintaining consistent braking performance.
3. Low Maintenance: Disc brakes require less frequent maintenance compared to drum brakes, resulting in lower maintenance costs and less downtime for repairs.

Drawbacks of Disc Brakes

1. Higher Cost: Disc brakes are generally more expensive to manufacture and replace, increasing the initial cost and potential maintenance expenses for vehicles equipped with them.
2. Vulnerability to Corrosion: The exposed nature of disc brake components makes them susceptible to corrosion, especially in harsh weather conditions.
3. Brake Noise: Disc brakes can produce more noise during braking compared to drum brakes, potentially affecting driver comfort and vehicle aesthetics.

Applications of Disc Brakes and Drum Brakes

Disc Brakes: Sports Cars and Performance Vehicles

Disc brakes are widely used in sports cars and performance vehicles due to their superior stopping power and heat dissipation capabilities. These qualities make disc brakes the preferred choice for high-performance applications where reliable and consistent braking performance is essential.

Drum Brakes: Commercial Vehicles and Economy Cars

Drum brakes are commonly found in commercial vehicles and economy cars, where cost-effectiveness and durability are crucial factors. The self-adjusting mechanism and parking brake functionality of drum brakes make them a practical choice for vehicles that prioritize affordability and functionality.

In conclusion, both disc brakes and drum brakes have their unique characteristics, benefits, and applications. Understanding the differences between the two braking systems can help vehicle owners and enthusiasts make informed decisions about their braking needs, taking into account factors such as performance, maintenance, and cost. Whether it's the superior stopping power of disc brakes or the cost-effectiveness of drum brakes, each braking system has its place in the diverse landscape of automotive technology.

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