What to do with brakes overheating and fade
Use of brakes for a long period of time will cause their overheating and can be dangerous for your life. What should you undertake to prevent it?
How a car brakes
The biggest number of modern cars have disc brakes. They can be solid or ventilated, slotted or cross-drilled, but all of them are clamped by pistons when you press the brake pad. This clamping results in friction which is the cause of slowing down. This friction is also a cause of heat that sometimes makes discs glow at night. The part of this heat is transferred to the brake fluid that is used by all brake pads. The fact is that all vehicles have different abilities of heat dissipation depending on the structure of their wheels.
What causes brake fade
Modern brakes are designed in accordance with the car mass they are installed into. For example, if you wish to pull a trailer that is half a weight of your car mass admit that your brakes must be able to cope with 50% more mass that it was planned initially. Think only if you drive down the high hill with a trailer behind. The increased mass will make your vehicle drive quicker even if you do not wish that, so a necessity to press brakes seems inevitable. If you hold on brakes continually, a huge amount of heat will be generated and they will be able to work only for a couple of hundred meters. Undoubtedly, the air will cool the brakes but only to the minimal degree, while a vehicle will be able to move slower only when heat dissipates.
How to use gears on the hill
Lorries in comparison with cars and motorcycles feature engine braking based on the engine compression. The latter ones can only do that if they switch to the lower gear.
In other cases your engine might over-rev, so to avoid it, it is better to start slowing down on the very top of the hill to have less heat to dissipate.
Brake fade types:
1. Boiling of the brake fluid
Continuous brakes application results in heating brake fluid that might even boil. That means that this fluid will not already cool brakes.
At the initial stage, the pedal will get softer because of air bubbles that appear in the brake fluid and are easy to compress. That will make you push the pedal further in order to achieve slowing down and gradually even pressing it to the floor will not give any braking power.
Brake fluid has a tendency to age and become more hygroscopic. That will decrease its boiling point and increase the boiling likelihood. That is why a necessity to transport heavy loads may be compensated by use of racing brake fluids that boil at the higher temperatures. You should also remember to replace the brake fluid if it has already boiled.
2. Green fade
If you decide to install new brake pads onto the already used brake rotors, it must be done properly as these rotors are smooth and more consistent. The brakes are checked by the manufacturer in the following way: the car is driven at a particular speed and stopped pressing brakes heavily. This procedure is repeated for several times at the equal intervals.
3. Brake pads glaze, melt or degrade
There is a special temperature range for brake pads. If the temperature goes higher than that pad materials might start melting and that results in disc lubrication. This creates an additional layer near the pad with less friction.
In case pads get overheated after they get cool, a glazed cover appears either on the pad or rotor. As a result, the pedal loses some percentage of tactility, becomes solid and has less braking power.
To function well they must undergo restoration or be replaced.
Actions to undertake in case of the brake fade
Theme are several actions you can undertake when you notice a brake fade:
- Lower the speed immediately;
- Go to the lower gear gradually trying not to over-revving an engine (you can opt only for revving that is a bit higher than a red line or you can bring about damages to the car);
- Turning round the corner will lower the speed;
- Try weaving to reduce speed though it is more dangerous to try it on the busy road;
- Gentle application of the conventional handbrake is possible; it will not work on vehicles with a hydraulic handbrake;
- Avoid switching to reverse or park in case with automatic gearboxes as it will burn it down;
- Find out an exit to drive off the road unless you stop gathering speed;
- In case you still gain speed it is necessary to drive to the terrain, bushes, shrubs etc.;
- As soon as you stop, the brakes will be hot red, so let them cool down. It is better to do that turning the wheels slowly to avoid warping brake rotors;
- Switch to the first gear to prevent speeding and turn on the warning lights to inform other road users about the problem.