Difference between drum brakes and disc brakes

25.03.2019
Difference between drum brakes and disc brakes

Difference between drum brakes and disc brakes ➤ Friction and heat ✅ Drum vs. Disc today ☝

Difference between drum brakes and disc brakes

Brake technology has really advanced in the recent years. It has come a long way, more that we can see in the suspension technology.  The systems begun in the ’60 as manufacturers competed to provide better braking solution. Because of this, brakes have really improved. 

Caron fiber, sintered metal and lightweight metal are some of the best things seen today. In addition, the adoption of ABS has made what seemed impossible possible. Among the advantages being the reduced stopping distance and improved safety in the vehicle.

In the 1970s, a major change took place in the automobile industry. There was, among manufacturers, a shift from drum to disc brakes.  The period saw most of the front-wheels receiving the new braking systems. The front wheel has been the major holder of braking power in many cars. And it still continues to be.  It made sense therefore, that only the front wheels would be upgraded.

This initial stages opened avenues for manufacturers to change the vehicles braking systems completed. The high end vehicles are fitted with four-wheel disc brakes. The performance models and the economy cars have not been left behind either.

But this did not render drum brakes useless. Time after time, manufacturers reverted to them as a way of minimizing production costs and purchase price. A good example would be the 1999 Mazda Protégé.

There are many reasons disc brakes are preferred over drum brakes. But does it make sense really, considering loss of braking occurs when using back drum brakes? This is for modern car. Let discover through this comprehensive guide.

Friction and heat

There are some basic principles applied in common between both systems. This is the first step you need to take towards understanding how these brakes work.

In essence, the brakes cause the vehicle to slow down by applying friction to the turning wheel. It is like some form of resistance working against the normal turning of the wheel.  The vehicle will eventually stop but with heat created as byproduct.

The rate at which the wheel can be slowed depends on:-

  • The weight of the vehicle. Heavier vehicles take longer to stop compared to lighter ones. And In case they are carrying any load, this rate goes higher.
  • Braking force. This is how much force you insert on the brake pedal. The higher the force, the faster the wheel stops.
  • Total braking surface. The brake pad that covers more surface stops the vehicle faster than one that is smaller.
  • The efficiency of the brake system. If the system converts the wheel movement into heat faster, the wheel will slow down faster.
  • How quickly the heat is removed from the component. Too much heat for a long time reduces the friction. If you are going to brake many times, you need a brake system that quickly removes the heat.

This is one of the areas you can find the right disk brakes vs. drum brakes comparison. Each of these types has varying way of handling this heat and that is perhaps the reason we don’t see much of drum brakes today.

 

Difference between drum brakes and Disc brakes

There is no denying that both of these braking systems play an important role where the vehicle’s safety is concerned. They both have advantages and disadvantages that are important to note.

Drum brakes

This is the earliest form of automobiles braking systems. They came after the hand levers, with a drum design on four wheels. There name came from the fact that the components were placed in a round drum. This drum rotated along the wheel.

There were shoes inside, which were forced against the drum when the brake pedal was pressed. Because it was necessary to transfer the brake pedal movement into the brakes shoes, fluid was a necessity. The shoes were heat-resistant, just like the ones on clutch plates.

 This design was quite basic and useful under some circumstances. Why then, get rid of the system? Because it has one major flaw that made it seem dangerous altogether. They would often fade and lose effectiveness under extreme pressure. For instance, on a steep slope descend while heavily loaded, and repeated high speed slowdowns. The drum built up too much heat and that is what caused the fading.

Here you can apply the principle of braking where kinetic energy is turned into thermal energy. In other words, wheel movement is converted into heat.  This means the drum brake will only operate within the heat it can absorb. When they become heat saturated, well, they will not halt the vehicle. The vehicle operator should be concerned about this. 

Disc brakes

Disc brakes rely on the same principle of friction and heat stopping a vehicle. However they are made with a far superior design than the latter. The major components are not housed. Instead, they use a slim rotor and a small caliper for effective braking.  There are parts in the caliper. They clamp together when the brake pedal is pressed. Fluid is also necessary for transferring the pedal movement into the brake pads.

The rotor in these brakes is fully exposed to the outside air. They are different from the drum brakes which allow heat to build up in the inside. The rotor receives faster and proper cooling at all times. As a result, the tendency of overheating or fading is reduced.

The first illustration to compare the difference s in both braking systems was discovered in racing. That should not be a surprise anyway. Racers with disc brakes had the opportunity to push the cars to the extreme limit. They were comfortable enough to step on the brakes only as the very last second. There was no risk of overheating. This led to more advances in automobile industry, with the adoption of the disc technology.

Drum vs. Disc today

The difference in the application of these brakes comes majorly from the type of vehicle. The four-wheel disc brakes for instance are very common on non-performance vehicles that value at middle-price. Surprisingly, many of the new models still use front-disc/rear drum brake setting.

Well, if you have been keen from above, you should notice that something is wrong.  The manufacturers are sacrificing the safety of vehicles. This is in order for them to save on a few coins in terms of price. They only install the disc brakes in the front wheels.

But then, this setup is sufficient for most vehicles. Both of these brake systems have been in use for the past 20 years, both have been approved. There is more improvement on the modern rear drum brake than the disc brake in the ‘70s.

The front brakes today have more stopping power than ever. The best part is, most are assisted by hydraulic systems to improve the braking power. This is just what you car needs since 60 – 70% of the stoppage power come from the front wheel.

For those with, high performance car like the Viper, and Corvette, you cannot do with the four-wheel disc brake system.  Especially if you are participating in a race, there should be no doubt what to go for in drum vs disc brakes choice. Otherwise, a vehicle that comes with four-wheel disc brakes also carries a higher purchase price.