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Your vehicle is only as good as its ability to stop when it needs to. A vehicle’s brake system — and the brake pedal itself — are vital components to safe, reliable stopping performance. Your brake pedal not only allows you to control the braking system in your vehicle, but can also be an indicator of issues that could compromise your safety. In this article, we will delve into the most common brake pedal problems and symptoms, how to identify the most likely cause, and what to do when brake pedal problems occur to ensure a safe, dependable ride.
Your brakes need to be dependable and healthy for safe vehicle operation and peace of mind while on the road — and your brake pedal is the first part of a reliable braking system. There are several common brake pedal-related issues that could arise, creating potential safety concerns and impacting your ability to stop effectively. Read on to learn more about the most common issues you may notice in your brake pedal, and what potential systems or components may be to blame.
My Brake Pedal Feels Spongy or Soft
A common problem with hydraulic braking systems is softness or sponginess, meaning that the brake pedal is easier to press down on than normal or doesn’t offer as much resistance until further into its depressed position. A spongy brake pedal can be caused by air entering the brake lines or a leak in the braking system. To test if your spongy brake pedal is a result of air in the brake lines, lightly press down on the brake pedal a few times. This compresses the brake hydraulic fluid and any air that may be trapped inside. If your brake pedal gets firmer after pushing down in quick succession, there’s a good chance there is air trapped in the brake lines.
Air in the brake lines is problematic, since air can be compressed (unlike brake fluid). When you press the brake pedal, the air in the lines compresses. This means that before the brake fluid pressure can reach the next pocket of brake fluid, the air must first be compressed, causing your brake pedal to travel farther before engaging the brakes. This can result in a less responsive braking system.
The most common cause of air in the brake lines is failing to properly bleed the brakes after a brake hydraulic system service. Bleeding the brakes is a common maintenance procedure to remove air trapped within the lines and ensure that there is no interruption in the transmission of fluid pressure. Correctly performing a DIY brake bleed can help restore the brake pedal's firmness and responsiveness if this is the only cause of your brake pedal’s sponginess.
If brake bleeding does not solve the problem, or only temporarily solves the problem, this may point to a leak or an area of the system where air is being allowed into the braking system. Checking the condition of your master cylinder and reservoir, brake calipers, wheel cylinders, brake lines, and brake hoses may help you narrow down the source of the problem.
A spongy brake pedal is an issue that requires prompt attention: It can cause less responsive braking, which may result in more effort or time needed to apply the brakes and stop. You may also notice an increased stopping distance. It is crucial to address a soft brake pedal promptly to ensure your brakes are functioning as they should. In some cases, it may be a good idea to park the vehicle until you can properly diagnose the problem to prevent complete brake failure from occurring on the road.
Why Does My Brake Pedal Sink to the Floor?
A brake pedal that sinks to the floor is indicative of an issue within your braking system, and should be addressed immediately, since a non-responsive brake pedal can affect your braking power and prevent your vehicle from stopping. A “sinking” brake pedal is one which does not have enough hydraulic pressure to return to its normal upright position, and can hinder responsive braking and overall safety. If you find yourself wondering ‘Why does my brake pedal fall to the floor?’, it could be due to a number of factors. These can include low brake fluid levels, worn brake pads, air in the brake lines, or a bad brake master cylinder.
Worn Brake Pads
Your brake pedal may also fall to the floor or travel farther than it typically should due to extremely worn brake pads or brake shoes. As brake pads and shoes wear out over time due to friction, the caliper and wheel cylinder automatically adjust to keep them close to the rotor. If you’ve recently compressed the caliper pistons during a brake service, whether you installed new pads or not, it’s necessary to pump the brakes a few times to ensure they return to an appropriate travel distance.
Air In The Brake Lines
As discussed above, air in the brake lines is another common cause of a sinking brake pedal. Air can enter the brake system through a leak or during a brake fluid replacement if bleeding is not completed properly. When air is present in the brake lines, it can compress, causing a loss of hydraulic pressure and resulting in a sinking brake pedal. The best solution to remedy air in the brake lines is by performing a brake bleed. If the problem is still present after this is completed, it may point to leaks or damage to other components. Anti-lock braking systems (ABS) may require a scan tool to bleed properly, as air can become stuck in the ABS module. If your vehicle is equipped with ABS and the brake fluid level has run completely empty, it might require a professional technician to ensure the system is properly and completely bled.
Defective Master Cylinder
The brake master cylinder helps transfer the force applied to the brake pedal into hydraulic pressure, which makes it possible to apply your brakes. Master cylinders and their internal seals can suffer from friction- and pressure-related wear, causing a brake fluid leak over time. This leak may be visible from outside the master cylinder, or fluid may escape through the back of the master cylinder and enter the brake booster, eventually causing damage to its internal vacuum diaphragm. Be sure to inspect beneath your vehicle for signs of a brake fluid leak, and check the brake fluid level in the master cylinder reservoir even if a visible leak isn’t discovered. If you feel confident that the brake master cylinder is the culprit, check out our video on a DIY brake master cylinder replacement for a complete, confident repair.
Why Is My Brake Pedal Vibrating or Pulsating?
Brake pedal vibrations can be caused by a few different issues, but in many cases, point to worn brake friction components. When you press the brake pedal, it should respond with a smooth and consistent motion and feel. However, if you feel vibrations or pulsations in the pedal, it could be a sign of a larger issue.
A possible cause of brake pedal pulsation is that the rotors have become “warped”. While it is possible for rotors to warp due to exceedingly high operating temperatures and other factors, warped brake rotors are most commonly rotors that have developed pad material buildup on their contact surface that causes unevenness. This is often due to improper brake pad break-in procedures or aggressive braking. When this occurs, the rotors no longer provide a flat surface for the brake pads to grip, leading to vibrations within the brake system and brake pedal itself. Inspect the brake system for any visible signs of wear or damage, such as worn brake pads or excessive rotor grooving, and replace these components if needed to maintain a dependable, safe braking system. You can also have the brake rotors resurfaced at your local O’Reilly Auto Parts to deglaze and flatten their surface and allow them to be reused.
Damaged or worn calipers may also cause the brake pads to wear unevenly, resulting in similar pulsation when the brake pedal is depressed. With the caliper removed, inspect the rotor and pad friction surfaces. If the pads are wearing diagonally, or if one side is more worn than the other, this may point to problems with the caliper, guide pins, or hardware, and can be a reason for vibration and noise while braking. You can also learn more about why your brakes are grinding with our helpful, detailed article.
Maintaining a responsive brake pedal is crucial for your safety on the road. By addressing any issues promptly, you can improve brake pedal feel and response, ensuring your vehicle stops when you need it to. O'Reilly Auto Parts offers replacement brake master cylinders, brake fluid, power brake boosters, and more to help you maintain and repair your vehicle's braking system.
If you’re looking for on-demand educational articles and automotive DIY videos, visit our How-To Hub for content like how to choose the right brake pads, symptoms of brake failure, and much more. Take advantage of our free Loaner Tool Program (refundable deposit required) if you need specialized brake repair tools, including rental brake caliper tool sets, to get the job done right while saving money.
If you’re still not confident about where to begin your brake system diagnosis, or need expert assistance, we can also recommend a professional brake shop near you for trusted service to keep your vehicle braking exactly as it should.