Why Are My Brakes Spongy? [Explained]

Published: 09/14/22 •  13 min read

Why Are My Brakes Spongy? – Symptoms, Reasons, and Solution

The brake pedal should be firm when you press on it. If it appears soft and spongy, there is something wrong.

Since brakes are a crucial component of managing your car, you should immediately have your car checked to identify the problem.

How Does a Brake Pedal Function?

Spongy brakes

No matter what brakes you use, the entire procedure begins with pressing down on the brake pedal. When you press the brake pedal to stop or slow your vehicle, the master cylinder reacts with a push of brake fluid through the lines of the brakes to trigger the piston. The caliper piston closes the rotor and presses on into the brake’s pads.

If your car is equipped with drum brakes, an actuator gets activated when you apply the pedal pressure. The brakes are then pushed upwards against the inside of the drum in order to reduce the speed of your car.

The hardness of the brake pedal results from the pressure in the brake fluid in the master brake cylinder and lines for your brakes.

What are Spongy Brakes or Soft Brakes?

In a standard operating brake system, you should experience minimal to no change in the brake pedal resistance at any time during the brake process. Various reasons could cause a spongy or hard pedal.

If you press on a spongy brake, what happens is instead of all the pressure being directed to the brake pistons, a portion of it is leaking out. When you release the brake, the resulting movement sucks up the air, and you feel an accelerator pushed directly to the floor with little resistance.

Symptoms Of the Spongy Brakes

Spongy brakes can affect the performance of your car, and, most importantly, they can affect your safety on the road. Here are a few obvious signs of spongy brakes.

The brake warning lights are on.

Some vehicles have an indicator light built into the dashboard, which flashes when the brake system has been impaired. This warning light on your car dashboard may be warning you of something ranging from an activated parking brake to a vehicle running low on brake fluid. It can be a sign of problems in the brake fluid pressure.

Your brake pedal is sinking.

If a vehicle cannot maintain brake pressure as efficiently as it ought to, it will cause your brake pedal to start sinking without resistance every time you press it. If your car’s brake pedals sink, it indicates that the brakes are experiencing certain issues, and you should have it examined immediately. To slow down your car by using this brake pedal, you would require to frequently apply brakes, as pressing the brakes just one time won’t be enough to create enough pressure.

The pedal needs pumping to keep it from slipping away.

If you have to press your brakes to reduce your car’s speed, make sure you check the brakes for the possibility of a leak of brake fluid. If the warning light for brakes is not lit and there aren’t apparent leaks of brake fluid, the master cylinder might be worn or leaking internally.

Causes of Spongy and Soft Brakes

The brake systems rely on equally dispersed tension to help bring the car to a complete stop. Any deviation from the balance of pressure could result in your vehicle needing more time, distance, or energy to slow down. This is what can cause tension imbalances that can lead to spongy brakes.

Fluid Leaks

A visible leakage of brake fluid out of an outlet or fitting is an obvious indication of a leak in the brake fluid. This may seem obvious however it is worth noting because there are some challenging situations. Since the fluid is being pushed away from the system, the system does not reach an amount that it could begin to move the pistons inside the wheel cylinders or calipers and, as a result, creates an unresponsive pedal.

There is a chance of a leak in the fitting, but no fluid is flowing from the port on the fitting. A fitting can draw air while the pedal is returned to its original place. Th

e air entering the system will naturally create a situation where the brakes need to be cleaned again.


1. Repair the leak

2. Perform complete bleeding of the brake system

This two-step procedure removes any leaks that may occur in the system.

Contaminated Brake Fluid

Brake fluid works just like the oil you use in the engine as well as in other mechanical systems inside your car. You must change the brake fluid at a minimum every two years. If the fluid is left for longer without being replaced, the fluid could absorb moisture and alter the fluid’s compression properties.

Another possible scenario in contamination of brake fluid can occur when a Dot 5 Silicone Fluid was utilized in the brake system, which had an original Dot 3 or Dot 4 fluid initially. Dot 5 fluid is a different type of brake fluid. Dot 5 fluid will not mix with other types of brake fluid and may result in the brake system’s ability to swell or form a gel. In addition, if the parts inside the system were not constructed using the correct type of rubber, the seals may expand and change shape or begin leakage. This could also result in an unnatural pedal.

WHEELSCRIBE Tip – If this is the case with your vehicle, a complete clean of the brake system is required.

Damaged Brake Caliper

Brake calipers, press your brake pads to the rotor in order to slow or stop your car. Braking is dependent on friction which generates a lot of heat. This heat could damage the disc brake caliper of your vehicle in the course of time. They may also become corrosion-prone when they are exposed to moisture. If the brake caliper has been damaged, it may leak and affect the hydraulic pressure.

The most common indicators of damage to calipers are:

Air in the System

The most typical reason for a soft brake pedal is the presence of air within the brake system. The best way to determine the issue is to press the brake pedal slowly several times. When you do this, the pedal should get firmer with each slight push on the pedal.

If so, the only solution is fluidizing your brakes. The most challenging part of taking the air out of the system is that it is difficult to be able to see the air and must think about air and the things it is doing.

It could be in the brake line, which has a strange bend in it, which is in an odd upward direction or might be trapped inside an area of high pressure in the caliper above the brake bleeding. In order to remove the air from a caliper, it might be necessary to take off the caliper, then move it around to ensure that the air pocket is in a position where bleeding brakes can push it away from the line.

If you feel that there is air in the system but you’re struggling to locate the source, we suggest an easy method of blocking off certain parts that are part of the system for brakes. You must remove the front caliprs and then apply the brakes. Then block the rear section of the system, and then use the brakes. If the pedal gets more robust and it loses the soft feel, it is possible to determine the location of the air, and you can begin to narrow your search to the rear or front of your vehicle.

It does not matter the amount of brake fluid you drain into the system of brakes. The air pocket could exist regardless of how much fluid is moved into the brake system.

WHEELSCRIBE Tip: If your air pocket is inside the caliper or line set unusually, move the line to allow an open-air pocket.

Low Brake Fluid

Brake fluid plays a crucial function in helping you slow down. It converts the applied pressure to the force needed to bring your car to a standstill. The lack of brake fluid can affect the brake’s hydraulic system and cause your brake pedals to fall.

Booster Pin Gap

In this case, the gap between the booster pin and the brake booster and at the rear of the master cylinder could be too big. As a result, nothing happens when you press the pedal, and then, suddenly, it appears there is the pedal.


1. The master cylinder should be pulled forward and measured the gap.

2. When the distance is larger than that recommended, the pushrod needs to be adjusted to bring it to the proper depth.

Worn out Master Cylinder

A master cylinder plays an essential component of your car’s brake system. It stores liquid for the brakes, produces hydraulic pressure, and distributes it to the rear and front brakes. It pushes the brake fluid to where it needs to go to bring your car to an end.

As time passes, the seals inside the cylinder could crack or leak. The master cylinder generates hydraulic pressure; any damage to it will greatly impact the brake fluid pressure.

The Master Cylinder bore size is incorrect.

It is a bit complicated to explain, but it can be a significant cause of the soft pedal. It is evident that the master cylinder bore size is contingent on the components of the system. Calipers with multiple pistons typically have a smaller bore master cylinder than one with a single, big piston.

If a small bore is used for the master cylinder, it will require more travel distance to produce the right amount of line pressure and volume needed to ensure proper piston movement in the caliper. This will allow it to achieve the proper clamping force.

WHEELSCRIBE Solution: It is crucial to get this right because a too big bore size could cause the opposite pedal to require enormous effort to reach the necessary volume and pressure.

Component Failure

This is generally concentrated on the master cylinder but can also be a part of other systems such as wheel cylinders, calipers, or even wheel cylinders.

Master cylinders are usually the main suspect due to internal seals failing. It is usually identified when a rugged pedal becomes more. The pedal should be pumped gently, and then press your brake lever. If, while holding the pedal, it begins to move downwards, you likely have an internal master cylinder that’s in the process of leaking internally and is unable to maintain pressure at the required level.

WHEELSCRIBE Solution: Replace the master cylinder and fully bleed the brakes.

Brake Hose Leak

This is a bit more than the previously mentioned leaks of fluid. Keep in mind that air can go where fluid cannot go. When the brake hoses have been used for a long time and worn out, they may leak air through the hose’s outside but not leaks of fluid. If the inner lining of the hose has been broken down, air will come in and leave the hose. It could be similar to a leak in the fluid.

WHEELSCRIBE Solution: There isn’t any way to diagnose the issue, which will necessitate changing the hoses. The good news is that if you look at the hoses and you feel they may be susceptible to being the cause of this happening, they have reached a point where they require replacement.

Leaking Wheel Cylinder

Certain cars are fitted with disc brakes for the front wheel and drum brakes for the rear wheel. Drum brake systems have drums that rotate to the wheels. Inside the drum are a set of brake shoes, which are forced on the drum with the help of the wheel to reduce the wheel’s speed.

The corrosion in the brake cylinder may cause brake fluids to leak and cause the reduction of the hydraulic pressure making the brake pedal feel soft.

ABS Modulator Problems

Vehicles equipped with the ABS (Anti-lock Braking) System (ABS) have a hydraulic system known as the ABS modulator. It’s responsible for optimizing the brake pressure that is delivered for each wheel. Damage to the modulator may result in a brake valve failing to function properly, resulting in a stiff pedal.

Unaligned Rear Brake Shoe

Drum brakes come with a self-adjusting mechanism that ensures a minimal gap between the brake shoes as well as the drum. If the shoe’s lining is worn out and there is an increase in the distance between the drum and the brake shoe grows, the adjuster can adjust to ensure that the gap is kept to a minimum.

If your car has a rear brake drum and you are pumping the brake pedal, it increases the pedal’s feel; the rear brake shoes might be out of alignment.

Mechanical Interference

This is rare but is still worth mentioning. There are occasions when everything is working fine. The pedal is smooth, and there are no known problems. But then, all of a sudden, typically after a specific event, the pedal can be spongy until it looks like it’s not there. However, it is usually pumped back after a few presses on the brake lever.

In this case, we’ve observed that at the full rotation of the wheels, the brake caliper could meet with an area of the suspension or frame. In this case, it will force against the caliper and then either stretch it out significantly or cause it to slide over the pins in the case of floating type. When this happens, the fluid will be pushed through the caliper.

Pushing the brake pedal for the first few times fills the caliper with a fluid like when you install new components. This is sometimes a challenge according to the circumstances, and each situation will be somewhat different.

Fixing a Spongy Brake Pad

Brakes are vital to the safety of a vehicle.

Although you could attempt to fix your spongy brakes by yourself, it is strongly recommended that you hand the work to a skilled mechanic.

If you notice any of the signs discussed above, we recommend checking your brakes by an expert technician immediately. It’s always safer to believe in the experience of a professional who can do the job for you. They can identify leaks in the brake system and flush your brakes with special equipment.

But, if you are driving and suddenly notice your brakes are spongy, you should quickly pump the brake pedal using your feet. Soft brakes are caused by the fact that the brake master cylinder in your vehicle cannot produce the required pressure for effective brakes. By pumping the brake pedal, you will create enough pressure to prevent the car from the edge of the roadway safely.

Wrapping Up

There are several possibilities for why you might be experiencing the spongy brake pedal. If you are experiencing one of the listed symptoms, ensure you have the vehicle promptly inspected by a reliable mechanic. While hiring a mechanic, ensure that it is ASE-certified and uses high-quality equipment and replacement parts. Also, ensure that you get a service warranty.