Brake fade – First of all let’s recap on how brakes work, specifically disc brakes.
Disc brakes consist of brake pads and brake discs. The brake pads clamp onto the brake discs when the brake pedal is pushed. This creates friction between the brake pads and the brake discs which creates heats.
This heat is the key to how brake systems work; they convert kinetic energy to heat energy. The faster they can do this the faster your car will stop.
Brake fade happens when the heat created is too much for the brake pad to handle.
All brake pads have a specific heat range in which they work well. If a brake pad is too hot or too cold they do not work properly.
Brake pad effectiveness is measured by its coefficient of friction. Companies like Ferodo will publish a graph for its brake pads which show how the coefficient of friction of the brake pad changes with temperature.
Brake fade happens when the brake pad becomes so hot it takes the brake pad outside its temperature window where it is most effective.
When brake pads overheat they emit gasses and can start to shed material onto the brake disc. This leads to a loss in friction between the brake pad and the brake disc. This can make the brake pads feel like they have turned into blocks of wood.
The symptom of brake pad fade is pushing the brake pedal harder but the car does not stop any faster.
In other words the stopping power loses its connection with how hard you press the brake pedal.
Needless to say this is a very disconcerting feeling.
There is another type of brake fade. Whereas brake fade of the brake pads is down to inappropriate brake pads ie the brake pads overheating for what they are being used for, the second type of brake fade is down to not properly maintaining the brake system
The second type of brake fade is related to the brake fluid in the system. Over time brake fluid absorbs water from the air and the more water it absorbs to more compressible it becomes. You can feel this compressibility as a soft/mushy brake pedal.
In the extreme, brake fade caused by old brake fluid can lead to a driver push the brake pedal all the way to the floor with little increase in stopping power. Arguably, brake fade because of old brake fluid is more dangerous than brake fade due to low quality brake pads.
Fortunately there are things that can be done to a car’s braking system to massively improve the braking system to brake fade.
The most obvious step is to flush out the old brake fluid completely and refresh with the new brake fluid, we recommend DOT5.1 brake fluid for a brake system that uses DOT4 brake fluid from the factory. New brake fluid will give immediate benefits. First of all the brake pedal will fell much stronger, it will give much more resistance and the car will seem to stop with less effort.
The second step is to upgrade brake pads. The brake pads fitted to cars from the factory are designed to bring a car to a stop from high speed once, possibly twice in quick succession. After this brake fade usually starts to happen.
This problem is quite easy to solve as there are many companies selling brake pads which are designed to work at higher temperatures than the original brake pads. These pads will be priced the same as what you get from a main dealer but they will far outperform the main dealer brake pads both for service life and in stopping power when hot. Brands like Ferodo and EBC make high performance brake pads for road use. Speak to your local performance car part dealer for advice on the pads which are best for you.
So in summary, brake fade is due to the braking system being asked to deal with more heat than it can handle. To raise the heat capacity of your car’s braking system new and/or uprated brake fluid should be used as well as performance orientated brake pads. Like most things, you get what you pay for, while there are cheap brake pads available their service life will not compare to performance brake pads costing 4 or 5 times as much.