A car without brakes is almost as incomprehensible as a car without a gas pedal. The brake systems in our cars and trucks are easily the most important safety system in our vehicles.
But, despite the many safety advances made in cars and in braking technology, brake systems can and do fail.
How do Brakes Fail? Brakes fail when any part of the brake systems wears out, gets damaged, or otherwise loses its function. The most common cause of brake failure is a brake fluid leak.
While brake failure may be one of the most dangerous mechanical failures that could happen to your vehicle, it is also one of the most preventable. In order to understand just how preventable it is, let’s look at some of the causes of brake failure.
Preventable Causes of Brake Failure
The brake system in your car is truly a system. It contains the brake pedal, brake fluid, brake lines, calipers, brake pads, brake discs and more.
It interacts with other systems in your car like the anti-lock brake system or the emergency brake assist system. Any breakdown in these systems can cause the brakes to stop working properly.
While brake failure is sometimes inevitable, most instances can be avoided by following your vehicle’s maintenance schedule and having your car serviced regularly.
Brake Fluid Leak
Even a small fluid leak can cause big problems for your brakes. The brake system relies on pressure to function, and a leak will cause that pressure to decrease.
Simply put, when you apply pressure to your brake pedal, brake fluid travels rapidly through your brake system and tells the brake pads to apply pressure to the brake disc. If there isn’t enough brake fluid, the system will not work.
Fluid leaks are usually found in the brake lines, but they can be found any place in the brake system where the fluid travels like the pistons, the fittings, and the reservoir.
Leaks are often caused by rust or pitting in the brake line, by a loose part, or by thin brake pads creating a caliper seal failure.
If you suspect your brakes are leaking even a little, it is time to get them checked out.
Brake Pad Issues
If your brake pads are worn down too far, they will not be able to do their job, which is to create friction with the brake disc. Service your brakes on schedule to avoid this problem.
If you overuse your brakes or drive aggressively, they can become overheated. This makes them harden and lose their ability to grip the brake disc. This is easily preventable by careful driving.
Water in the Brake Line
You can’t prevent water from getting in the brake line. It is just something that happens over time.
Brake fluid is hygroscopic, which means it absorbs moisture from the air, it is unavoidable. The brake fluid that sits in the reservoir is exposed to air. The fluid absorbs some of the moisture in the air, and eventually, it makes its way into the brake line.
This is typically only a small amount of water, and it can take years for that water to make a difference to the quality of your brake fluid.
However, 20% of drivers on the road have brake fluid that is 5% percent water, a level much too high for safe braking. (Source)
Not only does water in the line less effective than pure brake fluid, but it also lowers the boiling point and raises the freezing point of brake fluid. This can cause serious problems for your brakes.
You can keep this water from causing brake system issues by having your brake system serviced regularly.
Air in the Brake Line
There is no way to prevent air from getting into the brake line either. The system simply cannot be 100% airtight.
As the thickness of your brake pads decreases, other parts of the brake system must adjust so that the pads still press against the brake disc. This can lead to air entering the line.
Even though you cannot prevent air from entering the brake system, you can prevent it from causing problems by getting a brake fluid exchange or bleeding the brake lines at recommended times.
Overheating Brakes
The brake system can become overheated if it is overused, and not just the brake pads. The fluid in the brake line can actually boil, causing damage to the fluid itself and potentially the brake line. If enough damage occurs, the brakes will cease to function.
This can happen from aggressive driving – speeding up and stopping short and hard frequently – or it can happen when descending a steep hill and needing to apply the brake frequently in a short period.
While descending a steep hillside is not preventable, driving aggressively most certainly is.
Brake Pedal Sticking
If something falls behind your brake pedal, this will prevent you from pressing the pedal down. Be sure to keep the driver’s side floor clear of debris.
While this is not typically thought of as “brake failure,” it is certainly a problem with the brake system and one that is easy to avoid.
Causes of Brake Failure You Can’t Prevent
Damage to a Part of the Brake System
Whether through regular wear and tear or through an accident, damage to any part of the brake system will cause your brakes to fail.
For example, if the brake booster suddenly stops working, you will find it exceedingly difficult to press the brake pedal. In effect, your brakes will be unusable.
Regular maintenance will catch many of these mechanical issues before they lead to brake failure.
A Manufacturer’s Defect
Occasionally a manufacturer will make an error when designing a vehicle that could cause brake failure. Major defects result in companies recalling thousands of vehicles.
For example in 2018, GM recalled 210,000 vehicles after discovering a faulty brake component which could reduce the effectiveness of the rear brakes and would increase the likelihood of crashing. (Source)
Brake pad retailers, like Brembo, have also been known to put out recalls when they know their product does not operate the way it was intended. (Source)
While you cannot prevent a manufacturer’s defect, you can be sure to bring your car in for any recalls and use reputable mechanics who would be able to help you identify if a part they used in your vehicle was recently recalled.
Driving in Mud and Water
Brakes may also lose some of their stopping ability when you drive through mud or water. Mud and water can coat the brake pads and brake discs. This reduces the friction between them and will cause them to lose effectiveness.
You might not be able to control the weather, but careful driving on wet and muddy roads will help prevent an accident if your brakes fail.
This failure is typically temporary and tapping the brakes repeatedly should clear up the problem.
When It’s Not Brake Failure
In most vehicles when the anti-lock brake system (ABS) fails, it does not cause the rest of the brake system to fail.
The purpose of ABS is to pulse the brakes if your car starts to skid or comes to a fast stop. This helps prevent the driver from losing control of the vehicle.
If the ABS warning light appears on your dashboard, your ABS might not be working, but as long as the brake pedal is still functioning, and is not falling flat or locking up, the car is still technically drivable.
The car will be more prone to skidding, and if you need to come to a fast stop, you will be more likely to lose control.
You can pump the brake manually with your foot, but this is something most drivers aren’t used to doing because almost all cars on the road today have ABS.
Even though you can still drive the car, if you notice a problem with your anti-lock brake system, you should get it checked out as soon as possible. It is a popular safety feature for good reason.