Types of Brake Rotor Damage and Wear
Brake rotors are a crucial component of any vehicle’s braking system. When you press the brake pedal, it activates the brake calipers which clamp down on the brake rotors, creating friction that slows the wheels and stops the vehicle.
Over time and use, brake rotors can become damaged and wear down. Some rotor damage is normal from everyday use, but other types of damage can indicate more serious issues. It’s important to understand the different types of brake rotor damage so you can identify problems early and prevent bigger repairs down the road.
This article will provide an overview of the most common types of brake rotor damage and wear. We’ll cover what causes each type of damage, how to identify issues, and steps you can take to extend the life of your brake rotors through proper maintenance.
Normal Wear
Brake rotors are a consumable part that wear down gradually over time through normal use. As your brake pads clamp down on the rotor surface when stopping, tiny amounts of the rotor material get worn away with each brake application. This leads to the rotor becoming thinner as mileage accumulates.
Normal wear happens relatively evenly across the entire braking surface of the rotor. You’ll notice the rotor taking on a smooth, shiny appearance as the original milling pattern wears away. This is perfectly normal behavior. As long as the rotor remains thick enough overall, with thickness staying within specifications, this shining surface is not necessarily indicative of the need to replace rotors due to wear.
Signs that rotors are abnormally worn and in need of replacement include a substantial reduction in overall thickness or deep grooves/gouges in the surface material. If you notice any excess vibration, pulsing of the brake pedal, or loss of braking power, that can also point to excessively worn rotors that should be inspected and potentially replaced.
Heat Damage
Overheating is one of the most common causes of brake rotor damage. When the brakes are applied, friction generates heat. If the brakes get too hot from excessive braking or a stuck caliper, it can cause the rotor to overheat. This excessive heat causes the metal in the rotor to break down, resulting in damage and reduced braking performance.
Signs of rotor heat damage include discoloration, such as blue or purple spots on the rotor surface. The rotor may also develop hot spots that can be felt when running your hand across the surface. Heat cracks or grooves across the surface are also indicative of overheating damage. In extreme cases, the rotor may become warped or deformed from the excessive heat.
The best way to prevent overheating damage is through proper braking techniques. Avoid riding the brakes down long hills and allow time for them to cool after heavy braking. If you notice signs of overheating, have your brake system inspected and serviced promptly. Replacing brake pads and rotors regularly as part of routine maintenance can also help prevent heat damage from occurring. Keeping your brakes properly adjusted and wearing quality brake components optimized for heat dissipation will also help keep rotor temperatures in a safe range.
Grooves/Scoring
Grooves or scoring in the rotor surface is another common type of brake rotor damage. This occurs when the brake pads press against the rotor surface unevenly or when debris gets caught between the pads and rotors. The grooves are effectively scratches or indentations in the rotor surface caused by the brake pads grinding against them.
The main causes of grooved or scored rotors are:
- Worn brake pads that don’t make full contact with the rotor
- Foreign objects like rocks or pebbles getting caught between the pads and rotor
- Corroded and uneven brake pad material
- Not replacing brake pads when needed
Grooved or scored rotors can lead to a few issues:
- Reduced braking power and uneven braking
- Brake pulsation when applying the brakes
- Squeaking or grinding noises when braking
- Further uneven wear of the rotor and brake pads
In minor cases, grooved rotors may still be usable if the grooves are sanded down. But if the grooves are too deep, the rotors will need to be fully replaced. When replacing rotors due to grooving, the brake pads should also be replaced to prevent immediate re-grooving of the new rotors.
Some ways to prevent grooved rotors include:
- Replacing brake pads on schedule
- Having brake pads and rotors professionally inspected
- Avoiding driving with debris caught in brakes
- Replacing corroded brake hardware
Warping
Warping is another common issue that occurs with brake rotors over time and use. This happens when the rotor becomes warped and distorted from the high heat generated during braking. The main cause of warping is excessive heat buildup during hard or repeated braking. The rapid heating and cooling causes the rotor to expand and contract unevenly, leading to a warped shape.
Symptoms of a warped brake rotor include pulsating, surging, or vibrating sensations when braking. Your steering wheel or brake pedal may shake when braking at high speeds. You may feel the vehicle pull to one side when braking as well. Warped rotors can lead to a loss of braking power and uneven wear on brake pads.
To correct a warped rotor, resurfacing or replacing the rotor is typically required. Resurfacing involves machining off a thin layer of the rotor’s surface to restore a uniform thickness and flat surface. This can only be done a limited number of times before the rotor must be replaced. Replacing the warped rotor with a new one is the best option for more severe warping or if the rotor is too thin to resurface.
Cracking
Cracking of brake rotors can occur over time from extreme and repeated heating and cooling cycles. As the rotors heat up from friction braking, they expand. When they cool back down, they contract. This constant expansion and contraction can cause stress cracks to form in the metal.
Cracks are dangerous because they can quickly propagate and lead to catastrophic rotor failure. A cracked rotor is much more likely to shatter or break apart completely when braking force is applied. This can lead to a total loss of braking ability, which is an extremely hazardous situation.
It’s critical to inspect rotors regularly and look for early signs of cracking. Some tips for detecting cracks early include:
- Look for thin jagged lines on the rotor face. Feel with your fingers for raised edges.
- Spin the wheels and watch the rotors carefully. Cracks are often easier to see while the wheel is moving.
- Listen for clicking or popping noises when applying the brakes lightly. This can indicate rotor crack propagation.
- Be suspicious of any pulsating brake pedal that gets worse over time. This can signal rotor plate separation.
Addressing cracks as soon as they appear is vital for safety. If cracks are found, rotors should be replaced in pairs immediately.
Pitting/Rust
Rust is one of the most common issues that can develop on brake rotors over time. Rust forms when the iron material that brake rotors are made of is exposed to oxygen and moisture.
As the rotor’s surface corrodes, it develops a rough, pitted texture. This pitting and corrosion can decrease the rotor’s friction and braking power. Rust buildup can also cause squeaking or grinding noises when braking.
To treat surface rust on rotors, use sandpaper or emery cloth to sand the rusty areas smooth. This removes the pits and bumps caused by corrosion. Be sure to sand evenly across the entire rotor surface to prevent warping. More severe rust may require replacing the rotors.
To prevent future rust, keep the wheels and rotors clean by washing the car regularly. When the car sits for prolonged periods, place a breathable cover over the wheels. Always replace worn brake pads promptly, since worn pads can transfer metal debris onto the rotors and accelerate corrosion.
Preventative Maintenance
There are several ways drivers can help minimize brake rotor damage through proper maintenance of the brake system.
The brake fluid should be flushed at least once every two years to prevent contamination and maintain proper brake function. Contaminated brake fluid can cause corrosion in brake calipers and wheel cylinders.
Brake pads should be replaced before they wear down completely. This prevents damage to the rotor surface from direct contact with the caliper. The minimum pad thickness should be checked regularly.
Rotors should be resurfaced or replaced when severe grooving is present. Waiting too long can allow heat damage and cracks to form. Many brake experts recommend rotor replacement rather than resurfacing once they have been worn down substantially.
Inspected brake components for signs of leaks, damage, rust and abnormal wear at every tire rotation or brake pad replacement. Addressing minor issues early can prevent more significant damage.
Test brakes for proper operation and inspect all brake components during routine maintenance intervals as recommended by your vehicle manufacturer.
Finally,learn the normal braking feel for your vehicle model and pay attention for changes that could indicate issues. Addressing small problems early on can prevent major brake repairs later.
Diagnosing Issues
Inspecting your brake rotors regularly is important to identify any potential problems before they become dangerous or lead to more extensive repairs. Here are some tips on what to look for when diagnosing rotor issues:
Visually inspect the rotors for any abnormal wear patterns like grooves, cracks, or discoloration from overheating. Spin the wheels and watch closely for any pulsation, wobbling, or vibration which could indicate a warped rotor.
Listen for any abnormal noises like grinding or squealing when braking, as these can signify glazing or uneven pad deposits on the rotors. Feel for any pulsations through the brake pedal, steering wheel, or vehicle chassis when braking.
If you notice any of these warning signs, take your vehicle to a professional mechanic as soon as possible. Waiting too long with damaged rotors can lead to brake failure, a serious safety hazard.
Mechanics have the proper tools and expertise to thoroughly inspect the rotors, measure them for thickness variations, and determine if resurfacing or replacement is needed. Don’t put off diagnostic and repair work, as damaged rotors only get worse over time.
Conclusion
In summary, the main types of brake rotor damage and wear include normal wear, heat damage, grooves/scoring, warping, cracking, and pitting/rust. Properly maintaining your vehicle and staying on top of brake inspections and service can help minimize and prevent many of these issues.
Routine brake pad replacements and addressing any noises, vibration, pulling, or other irregular brake symptoms right away is key to prolonging the life of your rotors and brake system overall. Allowing damage and irregular wear to progress can accelerate the deterioration of rotors and other components.
This article provided an overview of the common signs of rotor damage and wear to be aware of as a vehicle owner. Understanding the various types of rotor wear and being proactive with brake maintenance helps avoid more extensive repairs down the road and keeps you safe on the road.