How brake problems manifest themselves and why it is important to do something about them

Recognizing and fixing brake problems

The braking system is one of the most complex and safety-relevant systems in a vehicle. However, many defects develop gradually and go unnoticed for a long time—until suddenly noises, vibrations, or a longer braking distance occur. Warning signs such as squeaking brakes, a spongy pedal feel, or a vehicle that pulls to one side when braking are clear indications that individual components are no longer working properly. At the same time, there are numerous problems that remain invisible to drivers and can only be detected during a professional inspection. This article shows which symptoms need to be taken seriously, what causes them, and why regular maintenance is essential for the reliability of the entire braking system.

Signs that brakes need to be replaced

The symptoms mentioned, such as squeaking brakes, jerky brakes, or a vehicle that pulls to one side when braking, are warning signs that drivers can notice immediately. They indicate that individual brake components are no longer working properly, are worn out, or have already been damaged. Noises such as grinding or a distinct brake smell after driving also indicate that the brake system is overloaded or that parts are already wearing heavily.

• Squealing brakes
• Brake judder or vibrations when braking
• Extended braking distance
• Soft or spongy brake pedal
• Vehicle pulls to one side when braking
• Grinding noises during braking 
• Brake odor after driving
• ABS or ESP warning lights active

Nevertheless, if these signs do not occur, it does not automatically mean that the brake system is in perfect condition. Many problems, especially with hydraulic components, brake hoses, ABS sensors, or inside drum brakes, develop gradually and often go unnoticed for a long time. Even heavily worn brake pads can sometimes function without making any noise or jerking until they suddenly lose their effectiveness. That's why you shouldn't rely solely on audible or noticeable symptoms. Regular inspections and maintenance of the brake system are crucial for detecting hidden defects, moisture in the brake fluid, uneven wear, or corrosion at an early stage. This is the only way to ensure that the entire brake system functions reliably, even if no abnormalities are noticeable in everyday use.

Typical problems with brake systems

Worn brake pads and brake discs

If a vehicle is frequently subjected to heavy braking, for example in city traffic with lots of stop-and-go maneuvers, on short journeys, or in wet weather, brake pads and discs wear out particularly quickly. Typical signs of worn components include squeaking brakes, uneven wear on the pads, and a pulsating brake pedal when decelerating. Over time, constant friction combined with frequent temperature changes changes the surface of the brake pads: the material can harden or "glaze," causing the pads to form a shiny, very hard layer. This layer noticeably reduces friction, the braking effect diminishes, and screeching noises often occur when the pedal is pressed. At the same time, local overheating can cause slight deformations (sideways runout or "wobbling" of the disc) on the brake discs. As a result, especially during heavy braking, there is noticeable jerking or vibration in the pedal because the warped disc no longer brakes the vehicle evenly. This reduces braking performance and increases the braking distance accordingly. If the pads are worn down to the metal backing material, metal-to-metal contact occurs, which severely damages the brake discs. Replacing the brake pads in good time is therefore not only important for safety reasons, but also makes financial sense, as additional new discs are required, which significantly increases the repair costs. In this case, a complete brake replacement is necessary instead of just replacing the brake pads, which significantly increases the cost of replacing the brake pads.

Mechanical problems with drum brakes

Drum brakes are also susceptible to wear and mechanical defects. Problems such as worn return springs, stuck or blocked adjusters, and warped (out-of-round) brake drums often occur. These defects manifest themselves in various symptoms. For example, worn or rusted springs and sluggish adjustment mechanisms prevent the brake shoes from being fully retracted from the drum. In practice, this often manifests itself in a slight grinding or squeaking noise while driving, as well as a delayed response from the brakes. If the drum is warped, for example due to overheating or material fatigue, you will feel noticeable vibrations or jerking of the brakes when braking. The brake pedal or even the steering wheel may shake noticeably. The reason? The warped drum presses unevenly against the brake shoes, resulting in only partial contact and irregular transmission of braking force. As a result, deceleration performance deteriorates and the vehicle brakes less effectively overall. If such symptoms occur, the only solution is usually to replace the defective parts. A warped brake drum, for example, cannot usually be repaired; the drum must be replaced and, if necessary, the brakes must be changed (including new brake pads).

Hydraulic problems in the brake system

Malfunctions in the hydraulic brake system are among the most safety-relevant problems in a vehicle. Typical symptoms of such malfunctions include a spongy, unusually soft brake pedal feel or a noticeable delay in brake response when the pedal is pressed. The cause is often old or contaminated brake fluid, especially due to moisture absorption over the years. Brake fluid is hygroscopic, meaning it attracts water. If the water content exceeds a critical value, the boiling point of the fluid drops so low that it can begin to boil under high loads. During heavy braking, vapor bubbles then form in the line system. Unlike liquid, gas is easily compressed, so the driver suddenly feels little resistance on the pedal. The pedal feels "empty" or spongy and must be pressed further; in extreme cases, there may even be an almost complete loss of braking power. Leaky brake lines or porous seals (e.g., on the master brake cylinder or wheel cylinders) can also cause similar effects, as leaks prevent sufficient pressure from being built up. At the latest when the brake pedal feels soft or requires more travel to be effective, this is a clear warning sign. In many cases, changing the fluid helps: Old or water-saturated brake fluid must be replaced regularly. A clear indication of this is when the fluid has clearly lost its function over time and the brake fluid needs to be changed. If this is neglected, there is a risk of vapor lock (vapor bubble formation) under high loads, which causes the braking effect to fail abruptly. Bleeding and changing the brake fluid remedies this and restores full hydraulic power transmission.

Overheating and brake fading

During long downhill drives, with heavy loads, or when driving in a very sporty manner, brakes can reach their thermal limits. Overheating of the brake system leads to brake fade, i.e., a noticeable reduction in braking performance due to excessive heating. The coefficient of friction of the brake pad material decreases as the temperature rises, so that less and less deceleration is achieved despite constant pedal pressure. After repeated or prolonged braking, braking distances are dangerously extended because the brakes no longer develop their full effect. Symptoms of overheating can include reduced braking power, a softer pedal feel when the brake fluid becomes too hot, or even slight vibrations. The latter occurs in particular when brake discs have already been damaged by heat shocks or extreme temperatures. At very high temperatures, brake pads temporarily lose their friction capacity and begin to literally evaporate. The binding agents in the pad can form gas, which forms a thin film between the pad and the disc and further reduces friction. In this case, the brake pedal remains hard, but the braking performance drops significantly. This is referred to as friction fading, which lasts until the pads have cooled down. If the brakes are repeatedly overloaded, the discs can also warp or develop heat cracks. At the latest when they cool down, this becomes noticeable through jerking and rubbing of the brakes, as the discs no longer run smoothly. Squeaking brakes often occur after heavy thermal stress, especially if the pads are unevenly worn or glazed in places. In the worst case, severely overheated components must be completely replaced. A complete brake replacement, including discs and pads, is often the only way to restore full braking performance.

Defective ABS and ESP sensors

Modern vehicles are equipped with electronic assistance systems such as ABS (anti-lock braking system) and ESP (electronic stability program), but their sensors can also be susceptible to malfunctions. Signs of a sensor problem often include warning lights coming on in the cockpit, uneven or unexpected braking behavior, or even the feeling that the brakes are behaving "strangely" at certain moments. The cause is often dirty, corroded, or damaged wheel speed sensors on the wheels. If these sensors send faulty signals, the control electronics can no longer regulate correctly. In practice, this can lead to the ABS engaging incorrectly even though no wheel is locked, causing the brake pedal to vibrate even during normal braking, as if the ABS were regulating when it was not necessary. A defective sensor can also have the opposite effect: the system does not recognize an impending wheel lock, and the ABS engages too late or not at all. The driver often perceives such failures as unstable or uneven deceleration; sometimes this results in a slight jerking when braking, but this is caused by electronic factors and not by a mechanical defect. In addition to ABS, ESP sensors (e.g., yaw rate sensors or lateral acceleration sensors) can also malfunction. This results in symptoms similar to those of ABS, such as unexpected intervention by the stability control system or warning lights. Important: Although a defective sensor does not require immediate brake replacement, it should not be ignored. Without functioning sensors, ABS and ESP cannot work reliably, which in an emergency can lead to increased braking distances or loss of vehicle control.

Stuck brake calipers or brake pistons

A seized brake caliper or jammed brake caliper is one of the most unpleasant brake problems, as it significantly impairs the braking performance of a wheel. Possible symptoms include the vehicle pulling to one side when braking and unusually high heat development on one wheel, often recognizable by the smell of burnt material. As the problem progresses, the brakes may also jerk or rub if the disc has already been damaged by overheating. The cause is usually stuck guide pins or a blocked brake piston, typically due to corrosion, dirt, or leaky sleeves. If the piston is stiff, the brake pad no longer detaches completely from the disc and rubs continuously. This causes constant friction and heat. After a drive, the rim on the affected side feels significantly hotter than on the other side. In extreme cases, the brakes may even smoke and smell burnt, a clear sign of overheating due to a stuck caliper. In addition to gradual wear, squeaking brakes often occur because the pad is tilted and rests unevenly on the disc. If the problem is not fixed, the brake discs may warp as a result of the constant heat, which in turn causes vibrations when braking. In such cases, there is no way around a repair. The brake caliper must be made functional again or replaced. In most cases, the brake disc and pads are already affected, so a complete brake replacement is unavoidable in order to restore the full function and safety of the brake system.

Why timely brake maintenance is essential

Timely maintenance

Timely maintenance of the brake system is one of the most important factors for long-term driving safety. Many brake problems do not arise suddenly, but develop gradually and can be detected early with regular checks. Signs of wear such as squeaking brakes, a decrease in pedal feel, or jerky braking behavior indicate that individual components need to be checked. Regular inspection of brake pads, brake discs, brake fluid, and moving parts can prevent safety-critical defects. At the same time, the braking distance remains consistently short and the braking force reliably available. Timely maintenance also prevents minor defects from leading to major damage to the brake system, which is beneficial for both safety and the service life of the entire brake system.

Costs of maintenance

The cost of maintaining a brake system can vary greatly depending on the vehicle model, type of brake, and wear condition. Nevertheless, they are relatively low compared to the potential consequential damage. Replacing brake pads is one of the most common maintenance tasks and is usually inexpensive, whereas replacing brake discs, wheel brake cylinders, or brake lines can be more costly. Regular replacement of the brake fluid is also important, as old fluid can lead to a softer pedal feel and increased braking distance. Although some drivers try to delay maintenance work, this often results in significantly higher costs in the long term, for example due to damaged discs or defective calipers.

Which brake components need to be serviced

Hydraulic components

The hydraulic system includes brake lines, hoses, wheel brake cylinders, and the master brake cylinder. They ensure that the pressure from the pedal is transferred to the wheels. Over the years, lines can rust, hoses can become porous, or cylinders and seals can leak. The brake fluid itself also plays a functional role in this area, as it enables power transmission and must be replaced regularly. If individual hydraulic components are leaking or damaged, they must be completely replaced to remedy the loss of pressure. A defect in this area is one of the most critical problems in a brake system, as it directly reduces braking power or causes the pedal to feel spongy.

Wear parts of the brake system

Classic wear parts include brake pads, brake discs, and brake shoes, which wear down continuously due to friction. Drums, discs, and in some cases even retaining clips also fall into this category, as they can also lose material or become deformed with intensive use. These parts must be checked regularly and replaced if necessary to ensure stable braking performance. Pads and discs in particular are replaced relatively frequently, as their wear is directly related to driving style, environment, and load. The earlier wear is detected, the lower the risk of damage to adjacent parts, such as discs or calipers.

Electronic components of the brake system

The electronic components of a braking system primarily include sensors and control systems such as ABS and ESP sensors, wheel speed sensors, and control units that monitor and correct braking behavior. When these components fail, it is often due to corrosion, contamination, or broken cables in the wheel area. Replacing the sensors is usually straightforward but essential, as faulty signals can greatly affect the brake force distribution and stability of the vehicle. Control units can also be replaced if they malfunction or no longer communicate correctly with the mechanical parts of the brake system. Modern vehicles rely heavily on these electronic aids, so a defect has a direct impact on safety and handling.

Mechanical components of the brake mechanism

The mechanical components include brake calipers, brake shoes, guide pins, return springs, and adjusters, which enable the actual movement and power transmission. In disc brakes, the guide pins and pistons are particularly susceptible to wear or corrosion; if they seize up, the pads no longer release properly and generate heat, noise, and uneven abrasion. In drum brakes, springs can fatigue or adjusters can become blocked, causing the braking effect to be delayed or uneven. These components can be replaced individually to restore the original movement of the brake mechanism. This is particularly important here. Even small defects can have a major impact because they disrupt the even distribution of force in the system.

Conclusion

Brake problems manifest themselves in many different ways, sometimes clearly audible or noticeable, sometimes completely inconspicuous. But regardless of whether the brakes squeak, jerk, smell unusual, or warning lights appear in the cockpit, any abnormality deserves attention. Many of the defects described can severely impair braking performance and dangerously increase the braking distance. At the same time, it is clear that there may also be hidden problems that can only be detected by regular technical inspections. Those who have their brake system serviced regularly and respond to warning signs at an early stage not only protect their vehicle, but above all themselves and other road users. Well-maintained brakes mean maximum safety in every driving situation.