Brakes – How They Work

Car brakes and brake in general work by changing kinetic energy into heat energy. Brakes do this by rubbing two surfaces together to create heat.

In the case of a modern car’s braking system these two surfaces are the brake discs and the brake pads. When the brake pedal is pushed the brake pads squeeze the spinning brake discs to create the heat and to slow the car down.

Performance brake parts increase the performance of a standard braking system by increasing the amount of energy that can be transferred in a shorter amount of time.

In a standard braking system the brake pads are usually the weakest link. Standard brake pads can be overcome by the heat being created which leads them to give off gas which gets between the brake discs and brake pads which massively reduces the friction available.

If you have ever felt this on the road you know what a “not good” situation this is. The symptoms of the brake pads overheating is a strong brake pedal, ie not soft, but no matter how hard you press the brakes you cannot lock the tyres and/or the car does not stop any quicker.

This problem of the brake pads overheating is called brake fade and is the biggest issue in standard braking systems.

To overcome this problem of the brake pads overheating performance brake pads can be fitted. Performance brake pads are designed to be able to cope with higher temperatures than the standard brake pads and have the side benefit of being able to last longer.

The downside of performance brake pads is that they tend to cost more than normal brake pads although you may get the money back through savings in garage costs because they could last 2-3 times longer than cheap replacement brake pads.

There is another type of brake fade and this is down to the brake fluid. Brake fluid absorbs water from the atmosphere and water has a lower boiling temperature than brake fluid. As brake fluid absorbs more and more water, its boiling point reduces.

The symptom of old brake fluid is a soft brake pedal under braking. The soft pedal comes from the brake fluid compressing. While water and brake fluid are not compressible, when brake fluid boils because of a high water content, the boiling introduces bubbles into the hydraulic system which are compressible.

If your brake pedal is close to the floor or if it is soft or if you need to push hard on the pedal to get meaningful retardation then your brake fluid may well need to be changed.

Brakes – Summary

Brake systems work by transforming kinetic energy into heat energy

The braking capacity of a brake system is limited to the amount of energy it can transform into heat

When the brake system is overcome with heat, brake fade occurs. This is usually down to the brake pads expelling gas or the brake fluid boiling

Upgrading brake pads to performance parts is a major improvement and regularly changing  brake fluid is also beneficial

For the ultimate increase in the heat capacity of your cars braking system a big brake kit is the answer.

 

This page was last modified Sep 27, 2011 @ 11:36 am

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