Having functional brakes is essential for any vehicle on the road. You also need to feel confident when using the brakes. This means the brake pedal should have just the right level of sensitivity and stiffness so that you can control brake pressure and modulate it depending on the circumstances.
However, sometimes the brake pedal can become hard to push. When this happens, it can make braking difficult. In a demanding braking scenario, stiff brakes might prevent you from depressing the brake pedal enough, causing an accident.
Common Causes of a Stiff Brake Pedal
You might be thinking “Why is my brake pedal hard?” If you have a stiff brake pedal, then your vehicle might have the following issues:
Faulty Brake Booster
Your vehicle’s brake booster is the part that multiplies the pressure exerted on the brake pedal. The brake booster allows the calipers to compress the rotors with a lot of force with minimal effort from the driver. Most brakes use vacuum pressure to help assist with braking.
A vacuum hose connects the brake booster to the engine’s intake manifold, allowing it to draw vacuum pressure from the brake booster using the check valve.
The brake booster works by allowing atmospheric pressure to enter the booster housing on the bulkhead side of the booster. Until you press the brake, there is vacuum on both sides of the diaphragm.
When you apply the brake, a spool valve in the rear of the booster moves to allow atmosphere to apply pressure to the back side of the diaphragm, the center of which is connected to the master cylinder. Thus, the pressure differential between the front of the diaphragm (vacuum) and the rear of the diaphragm (atmosphere) provides you the power assist you need.
However, as the braking system wears out, the brake booster eventually develops problems maintaining vacuum pressure. A rip in the brake booster’s diaphragm can form, or the check valve can fail. In both circumstances, the brake booster can lose vacuum pressure which powers the master cylinder. A faulty brake booster is the most common cause of a stiff brake pedal.
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Pro Tip: If you lose vacuum, as when the engine stalls, the vacuum check valve at the booster inlet maintains enough vacuum for one more power brake application.
Leaking Vacuum Hose
When vacuum hoses wear out, they can develop dry rot and crack. As previously mentioned, insufficient vacuum pressure can cause the brake pedals to feel stiff. Hence, when vacuum hoses develop leaks, they can cause insufficient brake booster performance.
Failed Master Cylinder
The brake master cylinder is the component that pushes brake fluid to the brake calipers when you press the brakes. Brake master cylinders have a limited lifespan. After several years of wear and tear, the master cylinder’s piston bore and seals will begin to fail. When this happens, one of the symptoms of a faulty master cylinder can be a hard brake pedal.
Failing Vacuum Pump or Power Steering Pump
Some vehicles will have brake systems that don’t rely on vacuum pressure on the intake manifold and will rely on an electric vacuum pump or hydraulic pressure from the power steering pump. If either the vacuum pump or power steering pump develops issues, then your brakes can feel stiff.
Seized Brake Caliper
Seized brake calipers are another possible cause of harsh or stiff brakes. Brake calipers and their associated screws might become stuck at times, preventing them from pressing on your brake pads. Since the calipers have a direct connection to the brake pedal, a stuck caliper can make the brake pedal feel stiff.
Sludge In Brake Lines
If you’ve tested your brake booster and discovered that it isn’t the source of your stiff brake pedal, the problem could be gunk in your brake lines. Brake fluid absorbs moisture that enters the brake system as a result of exposure to air. The presence of water causes sludge to build up over time, inhibiting the mobility of the braking fluid and making your pedal feel tight. To avoid sludge buildup, your vehicle’s brake fluid needs to be replaced at regular intervals.
Diagnosing and fixing these issues typically involves inspecting the concerned components. This can be difficult if you aren’t not familiar with the ins and outs of your braking system. If you’re noticing a hard brake pedal, ask an experienced mechanic to inspect your vehicle.
Have Faulty Brake Components? Get Replacements Online
Old and worn-out brake components like a brake booster, vacuum hose, or master cylinder can cause your brakes to feel spongy or even fail. You should replace worn-out brake parts immediately, as they pose a significant risk to you and your passenger’s safety. It’s a good thing that looking for replacement brake components is easy here at CarParts.com.
Our brake components are made to follow the precise specifications of the original part. This ensures that the replacement will function and perform just like the original. Aside from providing high-quality parts, we’re also committed to making them more affordable.
Don’t hesitate to replace your vehicle’s faulty brake components. Get brand-new brake boosters, vacuum hoses, or master cylinders at CarParts.com today!
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