5 Reasons Why Your Brake Pedal is Stiff
By Mavis Tire Team
Published 02/22/2025
What does a stiff brake pedal feel like?
If you’re driving with a stiff brake pedal, it may feel like you have to practically stand on the pedal to slow down or stop your vehicle. Additionally, your vehicle’s brakes have to work harder to slow down your vehicle when the brake pedal is stiff. Unlike a soft or spongy brake pedal, a stiff or hard brake pedal is a serious safety hazard that should be serviced as soon as possible. Let’s explore what could be the cause of a hard brake pedal.
Why is my brake pedal stiff?
Brake booster issue In most cases, a stiff brake pedal is caused by problems with the brake booster. Brake boosters multiply the force applied to your brake pedal, and they work in tandem with the hydraulic fluid in the brake lines. A faulty brake booster can no longer maintain vacuum pressure. The brake booster is connected directly to the engine’s intake manifold via a vacuum hose, allowing the process of drawing air into the engine to also draw air from the front chamber of the brake booster via a check valve. This system, also known as power brakes, allows you to stop a two-ton vehicle with just your foot! Most vacuum-assisted power brakes function because of engine vacuum, but sometimes, a tear will develop on the diaphragm or the check valve may break. In both cases, the brake booster may no longer create a vacuum and will fail to supply power to the master cylinder.
Failing vacuum pump or power steering pump Some vehicles have different types of brake boosters. In these vehicles, the brake booster can be a mechanical or electrical driven pump instead of using the engine intake manifold to create a vacuum. Also, some vehicles may have a hydraulic brake booster that uses direct hydraulic pressure generated by the power steering pump instead of the engine vacuum. If you have a stiff brake pedal and the vehicle has a vacuum pump or hydraulic brake booster, common issues could be a missing serpentine belt, a failing electric pump, or low-power steering fluid. No matter the brake type or condition you should be well informed. Consider taking a minute to check out our Brake Repair 101 Guide to learn more about the various brake systems and their various components.
Cracked vacuum hose A vacuum hose connects your brake booster to the engine, through which air is drawn to create a vacuum. Often, the loss of vacuum that leads to a stiff brake pedal is caused by a broken vacuum hose.
Seized caliper Another potential cause of a hard or stiff brake pedal is seized brake calipers. Brake calipers are one of the most essential components of your vehicle's braking system. The main job of a brake caliper is to push your brake pads against the rotor when you attempt to stop your vehicle. Sometimes, brake calipers can become stuck, preventing them from engaging and positioning your brake pads correctly. The result may be a hard brake pedal. If you're experiencing a stuck caliper, it's best to visit your local Mavis to have the issue resolved.
Sludge in the brake lines Your hard brake pedal may be due to sludge in your brake lines. Brake fluid absorbs moisture, which may enter the brake system from exposure to the air. Over time, the presence of water will cause sludge to build up, limiting the movement of the brake fluid, and causing a stiff brake pedal.
Is it safe to drive with a stiff brake pedal?
No, it’s not safe to drive with a stiff brake pedal, and it can be a serious automotive driving hazard to you, your passengers, and other drivers. If it’s difficult to press down on your brakes because of a hard brake pedal, and if your brakes aren’t working properly, coming to a complete stop or stopping in time at a red light may be difficult.
What should you do about a stiff brake pedal?
Considering how dangerous a stiff or hard brake pedal can be, you should have your brakes serviced immediately at your nearest Mavis store. As noted above, a hard or stiff brake pedal can be due to a host of many common causes, including a need for new brakes. Visit the experts at your local Mavis, and they can fix the problem and have you on your way.
