Brake fade is the brake system’s partial or total inability to stop the vehicle due to the brake pads’ overheating. In such a case, you have already tried to push on the pedal. Yet, the pedal remained high and firm while the vehicle continued to move. Brake fade can be an issue in vehicles that make use of friction braking systems.
Heat builds up in the braking surfaces, and for this reason, there is a big chance that the braking system may overheat, leading to brake fade. Brake fade can also happen due to the wearing off of the components of the brake system. Moreover, brake fade can occur in both disc brakes and drum brakes.
You can reduce brake fade by having the right materials and equipment for your brake system and having a good cooling system. Most brake fade instances happen during high-performance driving, like during a race or when you are tackling a descending road.
Moreover, brake fade more often occurs in vehicles with drum brakes because of their configuration. It seldom happens in cars with disc brakes because of their more resistant design to brake fade. Disc brakes have a design that allows the heat to vent away from the pads and rotor quickly.
4 Types of Brake Fade
Experts design brake pads to work up to a specific temperature. Moreover, they become more efficient when they get warm. Yet, they would begin to melt and break down beyond a particular temperature, and brake fade will ensue. Below are the different types of brake fade and their short descriptions:
1) Early Life Brake Fade or Green Fade
Green fade usually happens when the brake pads are newly fitted and the pads have not yet settled down with the other components after installation. This green fade will also go away after the pads have settled down. To lessen this type of brake fade, you should carefully drive when you have just fitted new brake pads into your brake system. Allow your new brake that extra time or bedding period. This bedding period can take up to 500 miles.
You can shorten the bedding-in period by utilizing the brakes well on a safe road stretch. In this way, you can get the pads to a moderately high temperature to burn off some volatiles that may cause green fade.
Nevertheless, before you engage in this, you need to ensure that the brake pads are well seated and make full contact on the rotor face. Don’t be overly aggressive with your new pads to not aggravate the issue and avoid the onset of hot spots on your rotor face. You can engage in several moderate stops to push your brake system past the green-fade period.
Some brake pads are already surface scorched. Surface scorched is a process of burning off surface volatiles and organics, which does away with green fade.
Furthermore, it will be useful to consider that brake pads come with a certain degree of porousness. Thus, they can absorb a minimal amount of water vapor from the surrounding. However, this water vapor quickly dissipates as soon as you get the pads to a specific temperature.
2) Dynamic Fade
Dynamic fade is a more severe type of brake fade due to your vehicle’s incorrect pad grade. It can also be due to a low-quality pad. It can also be caused by caliper drag. This type of brake fade happens when the caliper is not properly maintained. In this case, the caliper doesn’t fully release after applying the brake.
When your brake system fails to work when the bed-in period is over, this type of brake fade is called dynamic brake fade. Dynamic brake fade is dangerous because it can happen during track or fast driving and the driver has very little time for course correction.
Brake fade more often happened in the past when drum-brake vehicles were prevalent. Drum brakes had a limited or minimal cooling system. Thus, towing and heavily-loaded vehicles with drum brakes that wanted to stop during a long descent had their brake shoes superheated. This superheating caused the friction material surface to vaporize inside the brake drum, which often led to partial or complete braking capability loss.
3) Brake Fluid Fade
The brake caliper has brake fluid. It also heats once it works on the brake pads as it pushes these pads to come in contact with the disc. The caliper and the fluid heat up in this process and cause bubbles to form when the fluid boils and gets too hot. This boiling lessens the amount of fluid and limits the braking power of the brake system.
When brake fluid fade happens, you need to replace your brake fluid based on the vehicle’s service manual’s recommendation. Remember that the older the fluid, the more it will likely boil.
Brake fade due to brake fluid is a slow process that does not happen overnight. When brake fluid boils, bubbles develop in the calipers. The emergence of bubbles softens the brake pedal, and you need to push the pedal further because gas is compressible. Even with bubbles in the calipers, you can still halt the car by simply pumping the pedal more.
Nevertheless, the efficiency of the brake system diminishes when brake fluid fade happens. Thus, you must replace the damaged fluid completely. You can correct this problem by improving your vehicle’s cooling system and replacing your brake fluid with a higher grade of brake fluid.
It will be useful that you should keep your brake fluid fresh. Moreover, it will be best to remember that regular bleeding is vital to your braking system.
4) Pad Fade/Friction Fade
The most common brake fade type is friction fade. It is also called pad fade. Friction fade happens when the pad material begins to melt. For example, if you push on the brakes often when going downhill, hauling loads, or racing, friction fade may happen.
The brake pad comes with a peak temperature range. So, when you operate the brake pads beyond that range, the pads’ frictional materials will begin to degrade. When the frictional material degrades, the binding resins begin to out-gas.
This out-gassing creates a layer of heated gas between the disc and the pad. This thin film of gas makes the pad skid from the disc, reducing the friction between the pad and the disc momentarily. In turn, the braking power diminishes.
The high temperatures can also make the brake pads transfer an uneven and thin layer of friction onto the disc surface. The pads then rub on the brake disc’s rough surface and manifest irregular heat build-up over the disc surface.
Once the temperature goes beyond 650 degrees Celsius, it causes structural alterations and can form hard material referred to as cementite. This cementite becomes high spots that could lead to premature disc wear and brake judder.
Brake pads can withstand a maximum temperature of 1,200°F, and it is the resin or binder that primarily melts, and the melted resin or binder works like a lubricant between the rotor and the pad resulting in reduced friction.
Hence, this brake fade is called friction fade. The onset of friction fade leads to the rotors and pads being glazed over. When glazed over, the components of the brake system are already compromised.
Being cognizant of brake fade types will let you understand the reasons behind the onset of brake fade. It will help if you remember that, as a driver, you are liable for the damages and injuries brought about by the occurrence of brake fade or brake failure. Thus, it will be helpful to know why brake fade happens and be cognizant of how to prevent such brake fade.
The thing is, you need to maintain proper brake pad maintenance. This maintenance not only makes your car last but is also crucial to your safety as a driver. Regular checkup of your brake pads and the brake system helps you determine your brake pads’ level of wear and tear. Furthermore, it will be useful to note that the recommended time for having your brake system checked is every six months.