Visible brake pedal in a mercedes benz car interior

We regularly encounter car owners who are concerned about their brake pedal feeling unusually soft or spongy. This is a significant safety concern. If you notice your brake pedal travelling closer to the floor than usual, it’s imperative to have your vehicle inspected immediately for your safety and peace of mind. With years of specialised experience in brake systems, Sharp Brake is committed to diagnosing and resolving such issues. In this article, we’ve outlined some common reasons behind this problem and how our expert services can help. Remember, addressing brake issues promptly is not just about maintenance; it’s about ensuring your safety on the road.

Spongy Brakes After Bleeding: Air in the Brake Line

The most frequent culprit for a soft or spongy brake pedal is air trapped in the brake lines. Air can disrupt the normal flow of brake fluid, diminishing the efficiency of your braking system. At Sharp Brake, we recommend bleeding the brakes to remove this air. This involves flushing out the old brake fluid, which over time can absorb moisture and degrade, and replacing it with fresh fluid. This not only removes the air but also ensures other brake components, like the master cylinder and ABS (anti-lock brake system), continue to operate effectively.

Spongy Brake Pedal: Damaged or Leaking Brake Line

Rust and corrosion are major concerns for the steel brake lines in vehicles, with significant implications for safety and performance. Exposure to moisture and road salt can cause the steel to oxidise, leading to rust weakening the brake lines’ structural integrity and making them prone to developing small holes or fissures. Such deterioration is more than a cosmetic issue because it compromises the effectiveness of the vehicle’s braking system. The presence of rust and corrosion on steel brake lines requires vigilant monitoring and maintenance to prevent serious issues that can only be done by professional experts. Sharp Brake employs qualified mechanics who are knowledgeable about getting the job done thoroughly and properly.

The integrity of brake lines is critical for the proper functioning of a vehicle’s hydraulic braking system. When rust induced holes form in the brake lines, they allow essential brake fluid to escape. This fluid plays a crucial role in transmitting the force from the brake pedal to the brakes, thus enabling the vehicle to slow down or stop. A leak in the brake lines leads to a loss of hydraulic pressure, which in turn causes a “soft” or “spongy” brake pedal, characterised by the pedal being easier to press or going closer to the floor than usual. This loss of pressure can drastically reduce braking efficiency, increase stopping distances, and, in severe cases, lead to total brake failure. To maintain vehicle safety, regular inspection and prompt replacement of corroded brake lines are essential, along with ensuring proper maintenance of the hydraulic system.

Leaking Disc Brake Caliper and Worn Master Cylinder

Similar to brake lines, disc brake callipers can also suffer from corrosion, causing the internal piston seal to leak brake fluid. This leakage can significantly lower the brake pedal, or in some cases, cause it to reach the floor. Reduced fluid pressure in one calliper can lead to uneven braking or a brake pull.

The master cylinder is a critical component of the brake system that can wear out over time. At Sharp Brake, we’ve seen how both external and internal leaks, due to damaged piston seals, result in a loss of hydraulic pressure, leading to brake pedal failure.

Leaking Wheel Cylinder and Rear Brake Shoes Adjustment

In vehicles with drum brakes at the rear, the wheel cylinders are responsible for pushing the brake shoes against the drum to slow down the wheel. Corrosion inside the wheel cylinder can cause brake fluid to leak, resulting in a soft or spongy brake pedal. At Sharp Brake, we advise checking the rear drum brakes for proper adjustment, especially if pumping the brake pedal improves its response. Regular use of the parking brake can help in keeping these shoes properly adjusted.

ABS Hydraulic Assembly Malfunction

vehicles equipped with ABS, a malfunction in the ABS hydraulic assembly (or ABS modulator) can lead to a low or spongy brake pedal. At Sharp Brake, we’ve seen how internal failures or debris in the brake fluid can impair its function.


Remember that a spongy brake pedal isn’t just a minor inconvenience it’s a safety hazard. If you notice a spongy brake pedal when the engine is running contact Sharp Brake to have it checked by our professional mechanics immediately. Regular maintenance and prompt attention to problems will ensure the longevity and safety of your vehicle’s braking system.