The brake pedal is a piece of metal that every driver is very familiar with.
It’s what you press down on when you want to slow down.
You typically don’t think about your brake pedal – until it doesn’t work!
Then, you likely can’t stop thinking about it and need to get it checked by a mechanic immediately.
So what’s making your brake pedal act strangely?
And more importantly, what can you do about it?
In this article, we’ll explore how brake pedals work, what can go wrong with them, and the best way to get your brake pedal fixed.
This Article Contains
(Click on a link below to jump to a specific section)
- What Is The Brake Pedal And Its Role In The Braking System
- 3 Common Brake Pedal Problems
- How To Describe Brake Pedal Symptoms To Your Mechanic
- The Simplest Solution To Your Brake Pedal Problems
What Is The Brake Pedal And Its Role In The Braking System?
The brake pedal is the part of the car that initiates the entire brake system in a vehicle. In automatic cars, it’s the pedal on the left side, and in manual cars, it’s the middle pedal.
When you press down on it, all the components of your braking system swing into action.
How Does The Brake Pedal Influence Braking?
A person can typically apply around 70 lbs of force with their foot on the brake pedal. But to stop a vehicle, your disc brakes usually need roughly 800-1,200 psi of force at the calipers.
That 70lbs of force you apply on the brake pedal is amplified by different parts of the brake system — where ‘pedal ratio’ is one of the key amplification elements.
The pedal ratio defines how the force applied to the brake pedal is multiplied and transferred to the brake master cylinder.
It involves some physics that includes the brake pedal length, its pivot point, and the pushrod position of the master cylinder, but we’ll spare you the details.
After you press down on the pedal, the master cylinder transforms that force into hydraulic pressure in the brake lines.
This hydraulic pressure in the brake lines engages the piston at the:
- Brake caliper of disc brakes
- Wheel cylinder of drum brakes
The friction material on the brake pads (at the brake caliper) or brake shoes (on the wheel cylinder) then stop the wheels from moving.
What about the parking brake? Does it work the same way?
No. The parking brake system functions separately from the brake pedal’s hydraulics. It’s a safeguard to keep the vehicle at a standstill when parked and isn’t used for regular braking when the vehicle is in motion.
You now know how brake pedals work.
But what’s going on if your brake pedal isn’t functioning normally?
3 Common Brake Pedal Problems
You’ll rarely detect a physical problem on the brake pedal itself, but you can spot a brake issue from how the pedal feels when pressed.
Here’s what you should look out for:
Symptom 1: The Brake Pedal Is Soft Or Drops To The Floor
A soft brake pedal results in a mushy or spongy feeling, with minimal resistance when you depress it. You might even have a low brake pedal where it drops to the floor of your vehicle and doesn’t spring back correctly.
If you’re on the road when this happens, try pumping the brake pedal a few times to see if the pressure will build up in the brake lines, so that you can stop safely as soon as possible.
If you notice this happening before you even leave your driveway, don’t drive and call your mechanic instead.
Here are four of the most common culprits behind a soft brake pedal.
1. Air In The Brake Lines
Brake fluid is the conduit through which the braking pressure is applied.
The presence of air in your brake lines (that transport the fluid) will reduce the fluid’s hydraulic pressure, making the brake pedal feel soft.
Air can also make its way into a brake line during repairs, when you add brake fluid, or even during the vehicle’s general operation. Or worse, it can happen when there’s a leak in your brake system.
2. Brake Fluid Leak
The lack of brake fluid in your brake system will cause your brake pedal to drop with minimal resistance. A low brake fluid level can also trip the brake warning lights on your dashboard.
The most likely cause of this is a brake fluid leak, which can occur at many points in the brake system.
A leak can spring at the brake hose, brake line, or any piston seal at the master cylinder, brake caliper, or wheel cylinder. An aged master cylinder reservoir, too, can crack and seep brake fluid.
If there’s a puddle of brake fluid under your car (which will be a clear, light yellow to brown color, depending on its age), take note of where the leak appears. Its location can help your mechanic check what component is leaking.
3. Normal Brake Pad Wear
The brake pad or brake shoe isn’t meant to last forever.
As the pads wear down and reach the end of their life, the piston driving the caliper or wheel cylinder has to extend further to stop the wheel’s rotation. This will cause the brake fluid level to drop, and you may notice a lowered brake pedal.
The brake fluid reservoir is usually large enough to accommodate this eventuality. But brake pad wear can trigger problems in other components — like a leaking seal on a hyperextended piston.
4. Master Cylinder Failure
The brake master cylinder pumps brake fluid into the brake lines. Seals within the cylinder bore that contains the master cylinder piston can also fail due to age and wear.
When this happens, brake fluid will leak, dropping pressure in the brake lines, and you’ll notice the brake pedal sinking to the floor.
Symptom 2: The Brake Pedal Is Hard To Press
Problems in the brake system can also be reflected in a hard brake pedal. This is when you find that you need extra effort to press down on the pedal.
If this happens mid-driving and your brake pedal feels locked, don’t panic and lose control. Downshift your gears to use engine braking to slow the car. Once you’re moving very slowly, apply the parking brake gently to stop in a safe spot.
1. Brake Booster Failure
The brake booster amplifies the power in a brake system that has “power brakes.” Without it, stopping distances can increase dramatically, placing you at risk of collision during emergency stops.
It works by using the engine manifold as a vacuum source to multiply the force applied on brake pedals, making braking easier.
A front booster seal failure is the most common cause of a bad brake booster. When this happens, the reduced vacuum pressure makes it harder to press the pedal, or the brakes might not even engage at all.
Additionally, a front booster seal failure can also cause the rear seal on the master cylinder to fail over time.
Age or wear are factors that drive failure in a brake booster. Additionally, boosters can go bad faster for a driver who’s in stop-and-go traffic as the brakes are engaged more often.
2. Leaking Vacuum Hose
The vacuum hose helps deliver the vacuum to the brake booster. A problem with the vacuum hose (like a leak) can make the brake booster malfunction, translating to a hard brake pedal.
3. Extreme Brake Fluid Contamination
Brake fluid is a hygroscopic fluid, which means it absorbs water. Sludge will build up in the brake system over time and make it seem like the brake booster is failing.
When this happens, bring your car to the mechanic for a check and have your brake fluid replaced.
Symptom 3: Brake Pedal Pulsation
You might feel your brake pedal pulsating or vibrating from time-to-time.
Are pulsating brake pedals dangerous?
Mild pulsation is not an immediate cause for concern. However, you need to be aware that even mild pulsation can influence ABS performance on your brakes and increase braking distance during hard stops.
In extreme cases, or when wheel traction is marginal (like on slick or icy roads), pedal pulsation can cause uneven braking, making the vehicle hard to control.
Here are some typical causes of brake pedal pulsation.
1. Rotor Runout (Warped Rotor In A Disc Brake)
A warped brake rotor is shaped like a potato chip. The high spots on the rotor will push back against each caliper piston as they revolve between the brake pads.
That push back is transmitted directly to the pedal, causing it to pulsate. If the suspension bushings are worn, the steering wheel might even shimmy.
Warped brake rotors can be caused by:
- Improper installation of the wheel: Modern brake rotors are built thinner for faster cooling and reduced unsprung weight. This makes rotors more susceptible to warping due to a combination of heat and improper lug nut torque.
- Uneven heating or cooling: This can happen when you drive through a deep puddle on a dry day with hot brake rotors.
- Rotor contamination: Corrosion, clumps of brake dust, or anything else clamped between the hub, rotor, and wheel can create bending forces that will deform the rotor.
2. Rotor Surface Variation
If brake pads aren’t properly bedded-in or are severely overheated, the transfer of friction material (from brake pads) to the rotor can be uneven.
This creates a rougher rotor surface that’s felt in the brake pedal. You might even see stains or dark spots on the rotor from heavier deposits that won’t wash off.
3. The Rotor Needs A Fresh Surface
When your brake pads are worn, it can be tempting to install new brake pads and just leave them at that.
However, new brake pads (especially if they’re different materials from the old ones) won’t grip the old rotor as well and may cause the brake pedal to pulsate.
Resurfacing old rotors, or replacing them with new ones, gives the new brake pads a fresh surface for friction material to thinly coat during the bedding-in process.
4. Other Problems That Can Cause Brake Pedal Pulsation
There are other reasons for brake pedals to pulsate — like warped hubs, wear on the wheel bearings, or stiff CV-joints that cause the stub axle to wobble.
While any of these things alone could produce such a minimal runout that it can’t be measured, when combined, it can be felt in the brake pedal.
Clearly, there are tons of reasons for your brake pedal to act abnormally.
So, how do you explain it to your mechanic?
How To Describe Brake Pedal Symptoms To Help Your Mechanic
When the brake pedal behaves strangely, letting your mechanic know the exact symptoms can help them identify the source of the brake problem.
Here are some questions to ask yourself which will help you and your mechanic pinpoint the right issue:
- Does the brake pedal travel farther than usual when I press down?
- Does the vehicle stop normally, despite the low pedal?
- Does the pedal feel both low and soft, or is it low and hard?
- Does the pedal slowly sink into the floor when the brakes are applied?
- Does pumping the pedal once or twice cause the pedal height to rise or produces no noticeable effect?
- Does the pedal pulsate?
- Is it a combination of one or more of these symptoms?
As always, the best prevention for brake problems is to get regular brake service to ensure everything is working fine.
The Simplest Solution To Your Brake Pedal Symptoms
While it’s always a good idea to get your car serviced regularly to identify and repair brake pedal issues, make sure the mechanics you use are:
- Are ASE-certified
- Only use high-quality brake hardware for replacement parts
- Offer you a service warranty
Additionally, you may want to consider opting for a mobile mechanic who can come over and fix your brake problems in your driveway – instead of driving to a repair shop.
The expert technicians at AutoNation Mobile Service are a great option for this.
AutoNation Mobile Service is the most convenient mobile car maintenance and repair solution.
Here are the benefits of having AutoNation Mobile Service as your vehicle repair solution:
- Convenient, simple online booking
- Expert, ASE-certified mobile technicians will repair your brake pedal issues in your driveway
- Competitive, upfront pricing
- Your brake system maintenance and repairs are performed with high-quality replacement parts and equipment
- All AutoNation Mobile Service repairs come with a 12-month, 12,000-mile warranty
To get an accurate estimate of what your brake problem will cost, just fill this online form.
Always Pay Attention To Your Pedal
Your brake pedal plays a vital role in keeping you and your car safe.
So, the next time you get behind the wheel, pay attention to how your brake pedal feels, as changes in how it feels and behaves can indicate different kinds of problems with your brakes.
But, don’t worry.
If you do have a brake issue, AutoNation Mobile Service is just a few clicks away.
All you need to do is book an appointment online, and an ASE-certified technician will come fix everything right in your driveway!