Brake Pedal hard and Brakes Lock Up – Causes and Fixes

For almost all drivers, brakes are regarded as a device that makes them feel safe and comfortable to drive their vehicles. It gives them a feeling of control while driving. This makes them attempt any comfortable speed level. So they get particularly scared when their brake pedal hard and brakes lock up while driving; for most, it is regarded as the scariest thing ever.

Well, not to worry, we will let you what could have caused this problem and how to prevent it.

What Causes Brake Pedal Hard And Brakes Lock Up?

Many probable causes can make your brake system develop faults. If you want to know what causes brake lock up or hard pedal issues, though these issues are not entirely similar, here are some common causes to consider during fault inspection.

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  • Damaged Brake Lines
  • Sticky Brake Calipers
  • Hard Braking While Driving
  • Faulty Brake Pads
  • Insufficient Vacuum
  • Bad Brake Booster
  • Damaged Master Cylinder

Damaged Brake Lines

The brake lines transport brake fluid from your master cylinder to the brake calipers. This fluid is needed for the effective functioning and operation of your brakes. You practically won’t be able to use your brakes without brake fluid, so when your brake line is damaged, corroded, or leaking, it will hinder the transportation of brake fluid to your calipers, and this is not good at all. Your mechanic needs to get your brake line replaced or repaired if possible, depending on the damage’s extent.

Sticky Brake Calipers

Brake calipers are part of the topmost essential components of your vehicle’s braking system. The brake calipers hold your brake pads down against the rotors. When you assert pressure, your rotor’s kinetic energy is converted into heat energy, reducing your vehicle’s speed. Your vehicle cannot stop or slow down if your calipers are not functioning correctly. This fault can cause your brakes to lock up amongst other issues like steering difficulties and loose brake pedals.

It is relatively uncommon for you to have sticky brake calipers, but if you notice any problem with your brake calipers, get your car to a mechanic’s shop for inspection.

Hard Braking While Driving

Braking too hard while driving is a condition you can’t avoid sometimes, but you need to that braking hard has harsh effects on your braking system. Apart from the fact that it can cause your brake pedal to lock up so badly, you might also start experiencing overheating issues, and the damage still does not stop at your brake tubes or pads; it goes as far as affecting your tires. For drivers who regularly brake hard, this can trigger your ABS at an odd time and wear out various components of your brake system on time.

It may seem like a minor cause compared to other listed causes, but its effects are not laughable. You should form a good driving habit to avoid issues like this.

Faulty Brake Pads

Brake pads are most times, the reason behind your brake issues, including when your brakes lock up. Since the pads are used more often while driving, they are more prone to wear or other damages. That’s why vehicle maintenance is needed regularly. When you notice your brake pads are below a quarter thick, you need to replace them with new ones. You should be able to see your pads through your wheels’ spokes. If your brake pads are worn out, you might also hear noises while braking.

Insufficient Vacuum

A common cause of a hard brake pedal is a low vacuum. As your engine functions, the vacuum is gotten from your intake manifold or sometimes through your carburetor’s base plate. There is a vacuum hose between your brake booster and your intake manifold that supplies the vacuum. If the engine vacuum pulling the diaphragms in your booster is less than the atmospheric pressure in the booster’s rear end, then your diaphragm cannot move. This will make your pedal hard to press down due to no movement of the diaphragms.

Bad Brake Booster

Sometimes the cause of hard brake pedals might be a faulty brake booster. Your brake booster has moving parts at its front and back ends. If the diaphragm inside the booster fails, it will not hold vacuum or take in atmospheric pressure. This situation leads to difficulty in pressing down your brake pedals.

Damaged Master Cylinder

Your master cylinder is a vital part of your car’s brake system, usually located opposite your brake pedal under your bonnet. It has a significant function in your braking system’s effective operation, so if this component gets entirely damaged, your brake will immediately lock up.

If you already know what happens when brakes lock up suddenly while driving, you should now know how important it is to inspect your vehicle’s brake system regularly. If you notice any of these causes, get it fixed as soon as possible. You should take advantage of this knowledge for those who don’t know, so you don’t have to find out.

how to fix locked up brakes

How Do You Fix A Locked-Up Brake?

The fixing process of a locked-up brake depends on the actual cause of this effect. As we now know that several mechanical faults can cause your brake to lock up. So the first thing you need to do is inspect your vehicle and get the main reason for this problem before attempting a fix. Because if you have your brakes locked up car won’t move fine until you fix the actual cause.

For damaged Brake Lines

To best fix a damaged brake line, you have to get them replaced, but make sure you purchase the recommended brake line for your vehicle. This is very important. If the brake line of one wheel is bad, you should change your other wheel’s line, as it might soon get damaged also. You will need a quality brake fluid, new brake lines, some rags, and some necessary mechanics tools like a lug wrench, screwdriver, and jack stand for the replacement process. You can use a car lift if you choose.

You need to get your car raised. Check for the mesh line that passes through your piston’s housing to the metal side of your brake line. Remove the retainer clip at the hose fittings with a screwdriver. Once you have been able to remove the brake line’s fittings at its connection points, place your rag or a can under the connection points to prevent the brake fluid contained. Ensure your skin does not get in contact with the brake fluid.

If your line is attached to any other component, gently remove the connection. Now that your brake line is out use a reversal process to install your new brake line. It’s that simple. If you are not confident about doing this, you can always call your mechanic.

For sticky calipers or faulty brake pads

Fixing a sticky brake caliper is not a complicated process. Still, since you are dealing with a significant part of your brake system, you need to be inclined mechanically to perform this repair. To get this done, you will have to lift the side of the affected wheel using your jacks, or you can use a car lift to raise your entire vehicle. Once you’ve done that, unbolt your brake caliper with the right socket and remove the caliper from its bracket and detach the brake pads.

Use a brake cleaner to clean your caliper to wipe off any dust, debris, or grease on its surface. Also, clean the caliper pins. Inspect your brake pads. If you discover any damage, you should replace it. After that, lubricate the caliper pins and place them back on your brake pads. You might need some brake caliper tools to do this properly. Then place your caliper back to its bracket and tighten the caliper into position. You can now couple your wheels back and lower your vehicle.

For Damaged Master Cylinder

If your master cylinder is discovered to be faulty, you need to replace the cylinder. Get a recommended master cylinder and install, change your old brake fluid and bleed your brakes. You can check our previous article on how to bleed brakes. Check the whole of your wheels and wipe off any droplets of brake fluid. Fixing this issue can also prevent your brake locked up while parked for a long time.

Hard Brake Pedal – Brakes Locking Up/Locked/Sticking? YouTube


Q: Will a bad brake booster cause brakes to lock up?

Ans: A lousy brake booster is considered to be one of the causes of a locked-up brake. The booster helps to make your brake system more efficient by providing a smooth flow of brake fluid from your master cylinder as you increase pressure on your brakes. A damaged brake booster can make your brake pedal challenging to engage or feel spongy, making it less effective. It might be even lead to a complete shutdown of your brake system if not handled on time.
So if you are asking if will a bad brake booster cause brakes to lock up, then your answer is YES.

Q: What does it mean when the brake pedal is hard to push down?

Ans: Modern brake systems are designed with a brake booster, and this booster has a vacuum diaphragm that helps increase the force you apply on your pedal while driving, making it very easy for you to use your brakes. When you apply your brakes, your vacuum is closed, and this allows atmospheric pressure to go into a side of your vacuum diaphragm.

This will make your cylinders to be able to apply brakes. When you take off your foot from the pedal, the vacuum will return to the two sides of your diaphragm, and your cylinders get back to their usual position.
So when your brake pedal is difficult to push down, it means that your vacuum diaphragm in your brake booster is faulty and cannot move, so this will increase the force needed to apply your brakes, making it very difficult.

Q: Can a master cylinder cause brakes to lock up?

Ans: When your brake calipers and other brake parts are fully functional, and you still have brake locking up issues, the problem is mostly with your master cylinder. The master cylinder is among the essential components of your brake system. It is the valve that forces your brake fluid to pass through the brake lines, so your calipers can press your brake pads against the surface of the rotors. If this main component is damaged, your brakes will lock up.

Q: Will air in brake lines cause brakes to lock up?

Ans: Suppose air enters your brake lines, whether, from an incorrect bleeding process or a leakage point on your brake line, your pedal will be forced to compress the air instead of the brake fluid. This makes your brakes poorly function and might eventually lead to your brakes locking up if there is high air accumulation in your brake lines.

Q: What should I do if my brakes are locked up?

Ans: As a driver, you need to know what to do when your brakes lock up in case of any unforeseen circumstances. If this happens while driving, the first thing is to be calm, so you don’t make any anxious decisions. Turn your vehicle’s hazard lights ON and look for a safe place on the road to park your vehicle. You can also continuously use your horn to alert other motorists that you have issues with your brake system. Do not put off your engine until your vehicle has come to a stop.

If you were driving at a speed of below 40 mph, you could try activating your parking brake to put your vehicle to stop. If you are driving at a higher speed, do not use parking brakes. We can also help you out in situations like this.

Final Words

When you notice any issues with your vehicle brake system, that might lead to brake pedal hard and brake lock-up, you should get your vehicle inspected immediately to avert any unfortunate incident. You can get to us via email or in the comment box below for other information on how to fix locked-up brakes.

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Osuagwu Solomon

Osuagwu Solomon is a certified mechanic with over a decade of experience in the mechanic garage, and he has over five years of experience in the writing industry. He started writing automotive articles to share his garage experience with car enthusiasts and armature mechanics. If he is not in the garage fixing challenging mechanical problems, he is writing automotive repair guides, buyer’s guides, and car and tools comparisons.

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