What Are the Main Causes of Bad Brake Pads in Cars?
Brake pads play a crucial role in the braking system of a car. They are friction pads that create the force necessary to slow down and stop a vehicle by applying friction to the rotors when the brakes are activated. Proper functioning brake pads are essential for safe driving and preventing accidents.
When the driver pushes the brake pedal, brake fluid flows to the caliper piston which compresses the brake pads against the rotor. This friction produces the braking action that slows the wheels. Quality brake pads provide the grip and friction needed for efficient braking under various road conditions.
Replacing worn out or damaged brake pads is therefore vital for continued roadworthiness. Understanding the main causes of worn brake pads can help drivers inspect and maintain their brakes proactively.
Normal Wear and Tear
Brake pads are designed to gradually wear down through normal use over time. Friction between the brake pads and rotors every time you apply the brakes causes both parts to slowly deteriorate. Most quality brake pads will last between 30,000 and 70,000 miles before needing replacement (1,2). However, driving style, conditions, and pad material can impact the lifespan.
Driving Habits
Frequent hard braking is one of the main causes of premature brake pad wear. When drivers brake too aggressively and forcefully, it creates much more friction and heat between the brake pads and rotors. This excessive friction wears down the brake pads significantly faster compared to smooth, gradual braking (source). Sudden, hard braking essentially grinds away more brake pad material each time versus controlled braking which evenly distributes the wear (source). From a physics perspective, the high forces and power generated during sudden braking cause significantly more friction and wear even if the total energy is equivalent to gradual braking (source).
Drivers who frequently tailgate and brake at the last minute are much harder on their brake pads. Aggressive drivers tend accelerate and brake excessively, which wears the pads faster. Smooth braking allows the pads to last significantly longer. Learning to brake gradually and avoiding sudden stops whenever possible will help brake pads last longer.
Environmental Conditions
Environmental conditions such as rain, snow, and humidity can negatively impact brake pad performance and lifespan [1]. In wet weather, the extra moisture causes pads to wear more quickly due to increased friction and pressure. Humidity also introduces moisture that can be absorbed by brake pads, causing them to wear down faster [2].
Snow, sleet, hail and rain can accelerate corrosion and rust buildup on rotors and calipers. This rust causes friction between the pads and rotors, producing noise when braking. Covering vehicles when not in use helps minimize exposure to precipitation. Driving cautiously in wet, snowy, or icy conditions can also reduce unnecessary wear on brake components.
Manufacturing Defects
Like any product, brake pads can have defects stemming from the manufacturing process. This can lead to premature wear or even failure of the brake pads.1 Improperly formulated friction material or errors in the production process can result in substandard brake pads. For example, the backing plate is a critical component that provides structural integrity. If the backing plate is made with defective materials or the wrong thickness, it can crack or deteriorate faster than normal during braking. This can cause the friction material to separate and render the brake pad useless.
Other manufacturing defects like air pockets or uneven distribution of the friction material on the backing plate can also accelerate wear. Using lower grade materials to cut costs can produce brake pads that wear out quicker. Ultimately, manufacturing issues lead to premature failure of brake pads, posing a safety hazard and requiring early replacement.
Improper Installation
One cause of premature brake pad wear is improper installation. If brake pads are not installed correctly, it can lead to uneven pad wear. Some common installation errors include not matching the original brake pad specifications, failing to lubricate contact points, incorrectly securing the brake pad retaining clips and hardware, or not ensuring the brake pads can move freely in the caliper bracket.
Brake pads that are installed too tightly in the caliper can drag against the rotor, causing uneven and accelerated wear. Pads should be able to slide smoothly in and out as the caliper pistons extend and retract. Any binding or friction during install can indicate a problem. Always refer to manufacturer instructions and ensure proper fitment when installing new brake pads.
Overheating
Overheating is another common cause of premature brake pad wear and failure. As the name suggests, overheating occurs when the brake pads and rotors get extremely hot from heavy braking (source). This excessive heat can fade the pad material, glaze the rotors, and degrade the brake fluid, leading to reduced braking power and accelerated wear. Heat builds up through repeated hard stops or riding the brakes downhill. Overheated pads tend to lose friction and wear unevenly. Telltale signs of overheated brakes include brake fade, a burning smell, discoloration, and abnormal noise.
To prevent overheating, avoid unnecessary heavy braking and downshift when traveling downhill to use engine braking. Allow time for brakes to cool after heavy use by driving normally for a bit. Improper brake system components like inferior pads or small rotors can also cause overheating. Finally, contaminated brake fluid that has absorbed moisture will boil at lower temperatures, accelerating overheating (source). Flushing the fluid according to manufacturer service intervals helps avoid this issue.
Contamination
Contamination of the brake pads is another common cause of premature wear. This occurs when oils, greases, or other fluids come into contact with the brake pads. Common sources of contaminants include:
– Engine, transmission, or hydraulic fluids leaking onto the pads
– Lubricants from the suspension or wheel bearings getting onto the rotors and transferring to the pads
– Road grime, especially in wet conditions, building up on the rotors
As explained in this article, when the pads become contaminated, it alters the friction properties and causes uneven and accelerated wear. The pads will have reduced braking effectiveness and may start making squealing or grinding noises.
Oil and grease are especially problematic contaminants. They act as lubricants, minimizing friction and preventing the pads from gripping the rotors properly. This forces the driver to press the brake pedal harder, which generates more heat and exacerbates the wear.
The best way to prevent contamination is by fixing any fluid leaks and inspecting the brake components regularly. Contaminated pads need to be replaced and the rotors thoroughly cleaned or possibly resurfaced.
Caliper Issues
One of the most common causes of uneven brake pad wear is a malfunctioning caliper [1]. The caliper contains pistons that press the brake pads against the rotor when the brakes are applied. If one of the caliper pistons sticks, it will cause increased pressure on that pad, wearing it down faster than the other pad.
Sticking caliper pins are a common culprit for uneven pad wear. The caliper pins allow the caliper to slide back and forth as the brake pads wear down. If the pins get corroded or frozen, the caliper can get stuck, applying constant pressure to the brake pad on that side. This constant dragging causes the pad to wear down prematurely [2].
Replacing sticking caliper pins and lubricating them properly can often fix uneven pad wear from caliper issues. In severe cases, the entire caliper may need to be replaced to resolve uneven wear.
Conclusion
Regular brake inspection and maintenance is critical for vehicle safety (The Importance of Regular Brake Inspections: Ensuring …). Brake issues are among the top reasons for vehicle failures and can lead to dangerous situations if not addressed proactively (Brake Inspection: Signs you need one and How to do it). According to experts, brake inspections and fluid checks should be part of regular maintenance schedules to identify potential problems before they escalate into safety hazards (The Importance of Car Brake Inspections to Avoid Collisions).
In summary, regularly inspecting brake components through visual checks, measurements, and testing brake fluid is key for continued safe operation. Identifying issues early allows for repairs and replacement before catastrophic failures occur. Following recommended inspection intervals and addressing problems promptly helps avoid collisions and ensures the safety of passengers as well as other motorists.