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What causes soft and spongy brakes and how to fix it?

Table of Contents
Rear-Brake-Shoe-Adjustment

The presence of air trapped in the brake system is indicated by a spongy pedal. At the same time, if the brake pedal isn’t pressing firmly enough, hydraulic pressure is low.

If your brake pedal feels spongy, it could be due to air in the system, tainted brake fluid, a bulging hose, worn brake parts, or a sticky caliper.

The softness of the brake pedal could be due to a brake fluid leak or a malfunctioning master cylinder.

When you press down on the brake pedal, does your car’s braking system feel soft or spongy? That unsettling feeling can significantly jeopardize your vehicle’s overall safety. Actually, you should not drive at all until the issue is resolved; the dangers of a soft or spongy brake pedal are too great.

Whether you want to handle the problem on your own or hire a professional, it is good to be aware of what could be causing the worry.  

You should probably just not drive at all until you get that spongy or soft brake pedal corrected; it’s that unsafe.

How Are Spongy Brakes Distinct from Soft Brakes?

When compared to a soft brake pedal, the sensation of a spongy pedal is marginally different. When you press down on the brake pedal with a sponge brake, it seems like you’re working against a spring. Conversely, a too-squishy brake pedal will either touch the floor or slide down too far.

Signs of Spongy and soft Brakes

Some scenarios in which a driver might encounter mushy brakes are as follows:

  • The pedal that applies the brakes keeps making a downward motion.

The pedal may sink to the floor every time the driver presses down on it if the brake pressure is not efficiently held by the car. If the brake pedal sinks, it’s time to have the brake system checked out.

  • Even Now, the Brake Warning Lights Are On.

When a vehicle’s brake system is damaged, the dashboard indicator light will typically light up. Please have your vehicle evaluated by a professional if any of the brake lights remain illuminated at all times.

  • To reduce the vehicle’s speed, the brake pedal must be pressed.

In order to slow down, a driver should have a mechanic check the brake system if they have to pump them multiple times. If the brake pedal is being pumped, it can be a sign of a leaking fluid or a master cylinder that is worn out.

What Makes the Brake Pedal Spongy or Soft?

A spongy pedal is a common symptom of air trapped in the brake system. Obviously, there are more possibilities besides air trapped in the system. When your brake pedal seems spongy, it could be due to any of these issues:

Low Brake Fluid Level

Low brake fluid is a typical cause of mushy brakes. When it comes to something as mundane as monitoring your fluid levels, it’s easy to forget. Among the many fluids in an automobile, brake fluid is one that needs frequent inspections to avoid spongy or nonexistent braking if the fluid level drops too low.

Making routine checks of your braking fluid is the surest approach to avoid this problem.

Air in the Brake Lines

If there is air in the brake lines, it could also lead to mushy brakes. On long trips or when driving over bumpy roads, air can enter your car’s braking system. Because there is more resistance to the pedal’s pressure, the brakes may become less effective or even mushy if this occurs.

Removing any surplus air from your brake line is the easiest method to remedy this. A skilled mechanic can perform this with the help of specialized tools, although it’s not always straightforward.

Worn Brake Pads or Rotors

It is recommended that you inspect the braking rotors and pads. When brakes are worn down, they are less able to resist pedal pressure, which can lead to a mushy or inconsistent braking action.

change brake pads

Brake Fluid Contamination

The fluid has been left unchanged for an extended period of time.

Like engine oil, brake fluid is essential to the proper functioning of your vehicle’s mechanical parts.

At the very least, you should change the brake fluid every two years.

Long periods of time between fluid changes might cause the fluid to collect moisture from the air, altering its compression characteristics.

Different sorts of fluids are present in the vehicle.

The installation of a Dot 5 Silicone Fluid in a brake system that was initially equipped with a Dot 3 or Dot 4 fluid is another example of contaminated brake fluid. Dot 5 fluid can gum up or gel up systems if mixed with other types of braking fluid. Additionally, the seals can enlarge, alter form, or begin to leak if the system’s components are not made with the correct kind of rubber. A soft pedal will also result from this.

If your application falls into this category, it is necessary to thoroughly flush the braking system.

Booster Pin Gap

It is possible that there is an excessively wide space between the booster pins of the brake booster and the rear of the master cylinder in this case.

How does it feel?

“A pedal appears out of nowhere after I press down on the pedal and nothing happens.”

How about the solution?

  • To find the gap, step one is to advance the master cylinder.
  • It may be necessary to adjust the pushrod to reduce the gap down to the acceptable depth if it is more than 020″.

A mismatched bore size for the master cylinder

This becomes trickier to describe, yet it’s one of the main causes of a spongy brake pedal. It stands to reason that the components of the system as a whole will dictate the master cylinder bore size. Master cylinders with lower bore sizes are more commonly used by calipers with many small pistons rather than by those with a single huge piston.

The issue:

It will take a lot longer distance to generate the right amount of volume and line pressure to acquire the right amount of piston travel in the caliper to obtain the necessary clamping force if the master cylinder has a bore that is too tiny.

The inverse effect—a pedal that requires an enormous amount of force to achieve the required volume and line pressure—occurs when the bore size is too big, therefore it’s crucial to get this correct.

Component Failure

While this most commonly affects the master cylinder, it can also affect other parts of the braking system, such as the wheel cylinders or calipers.

Internal Seals of Master Cylinders Deteriorate

When internal seals fail, the master cylinder is typically the one to blame. The worsening of a pedal that was already slightly soft is a common indicator of this. While holding down the brake pedal, slowly press down on the pedal. A master cylinder that is internally leaking and unable to maintain the required pressure is likely to blame if while pressing down on the pedal, it begins to slip downward.

How about the solution?

  • Step one: swap out the master cylinder.
  • The second step is to fully deflate the brakes.

Brake Hose Leak

This extends somewhat beyond the fluid leaks that were already discussed earlier. It is possible for ancient brake hoses to leak air through the outside while still holding fluid. Keep in mind that air can move through spaces that fluid cannot. This situation is quite similar to a fluid leak: air can enter and exit the hose if the inside has broken down. It seems that changing the hoses is the only solution to this problem; unfortunately, no diagnostic tools are available. The bright side is that the hoses are likely old enough to require replacement nevertheless if you notice any signs that this could be the case.

Interference from Mechanical Factors

This is far less prevalent, but it deserves some attention anyway. On occasion, everything functions as it should. The pedal has a nice feel, and thus far, no problems have been reported. The pedal will become quite soft, almost nonexistent, after a certain event, but it can generally be pushed back up to solid with a couple of hits of the brake pedal. Here, we saw an instance when the caliper might touch a part of the frame or suspension when the wheel is fully turned. In such a case, the force exerted on the caliper will either cause it to bend considerably or, in the case of a floating caliper, to move along the pins. This is similar to how fluid is forced out of a caliper when new components are installed; pushing the brake pedal for the first few times is like filling the caliper with fluid. Every circumstance is likely to be slightly different, however depending on the scenario, fixing this can be tough at times.

The disc brake calibration is leaking.

Disc brake calipers, similar to brake lines, can corrode and rust, causing the internal piston seal to leak braking fluid. This component clamps the brake pad against the rotors to slow or stop the vehicle. When the brake caliper is leaking, it might lead to the pedal going all the way to the floor or very low. Decreased hydraulic pressure at the caliper is another possible cause of a brake draw.

Adjusting the Shoe Brakes

If the vehicle’s rear brakes are drum or shoe-mounted and pressing down on the pedal makes the brakes work better, it could be because the shoes are misaligned. A possible cause of the problem could be the lack of adjustment for the rear shoes as they wear. If your shoes are showing signs of wear, get them adjusted. In order to avoid accidents, you should occasionally apply the parking brake. The parking brake automatically adjusts the brake shoes when it is engaged.

parking brake shoes

How to Fix Brakes That Are Soft or Spongy

Unless you’re an expert, you should probably leave your car’s brakes alone. Leave the diagnosis and repair of your car’s braking problems to a professional if you are unsure of your abilities.

In order to identify and fix spongy or soft brakes, you need to check the service history of the brake system.

However, if you’re handy around the house, you could likely figure out what’s wrong with your spongy or soft brakes and fix them without calling a professional.

Before anything else, check to see if the brake system has been serviced recently. Air can enter the hydraulic brake system through any opening that is used for maintenance. Bleeding the system of that air is necessary for the brakes to function correctly.

So, before you try anything further, check sure the brakes are bled properly if your car’s brakes seem spongy or mushy after you worked on the hydraulic system.

Verify that you are bleeding the brakes correctly by consulting a repair manual or database if the problem persists after bleeding. There is a lot of variation in bleeding methods between automobiles nowadays. You might even require a scan tool to complete the task correctly in certain instances.

But hold for a second—what if there has been no recent maintenance on the braking system? The next step in troubleshooting the brake system is to conduct a comprehensive diagnosis.

Begin by examining the level and condition of the brake fluid. Finding and fixing the source of a leak is necessary if the brake fluid level is low. Additionally, flushing and bleeding the system is necessary in the event that you discover that the braking fluid is contaminated.

The brake shoes and pads (if any) should be examined next. Spongy brake pedals can be caused by severely worn shoes or pads, although this is not very common. In the process, make sure you inspect the brake calipers and wheel cylinders (if applicable). Inspect the brake system again and replace any broken parts.

-Brake-2

If everything seems to be in order so far, you’ll have to go into more in-depth diagnostics. Separating the master cylinder from the rest of the braking system can help you identify the source of the problem. Finding the right diagnostic method often requires consulting a repair handbook or database.

Is it safe to drive if the brake pedal is soft or springy?

Keep in mind that a car with a soft or spongy brake pedal is dangerous to drive. Your vehicle may experience a significant decrease in braking capability or complete brake failure. Until the issue is resolved, refrain from operating the vehicle.

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