Scoring or grooves in brake rotors are among the most common signs your brakes need attention. But while it most times indicates that your rotors are at the end of their lifespan, it could also mean you’re dealing with underlying issues – especially if you recently had your brakes checked. So, what can cause grooves in brake rotors? And what happens if you keep driving with it?
In this article, we walk you through the causes, the consequences of driving with this condition and how to address the issue. At the end, we answer your top questions. Let’s dive in!
What Causes Grooves in Brake Rotors?
Brake rotors are subject to wear and tear like any other part of your vehicle. The most common cause of minor grooves in brake rotors is normal wear and tear from the brake pads. However, if there’s an underlying issue, such as worn-out brake pads, malfunctioning brake calipers, or lodged debris, it can cause deep or excessive grooves that can result in various symptoms and increased maintenance costs.
Listed below are the most common causes for grooves in brake rotors:
- Normal Wear
- Worn-out Brake Pads
- Uneven Brake Wear
- Malfunctioning Brake Caliper
- Dry Guide Pins
- Rust or Lodged Debris
1. Normal Wear
Every time you use your brakes, the brake pads and rotors undergo friction. This friction, essential for the brakes’ stopping power, inevitably leads to wear and tear over time.
As miles accumulate, even if there’s nothing technically wrong with the braking system, the consistent contact and heat can lead to minor grooves and lines on the rotor’s surface. While some wear is normal, excessive wear can indicate other issues.
2. Worn Out Brake Pads
Brake pads are made with a wear indicator in most cases. This small piece of metal embedded into the pad will come into contact with the rotor when most of the brake pad material has worn away.
This metal indicator constantly scrapes against the rotor when the pads are severely worn, causing noticeable grooves. If not addressed, this metal-on-metal contact can cause significant damage to the rotor.
3. Uneven Brake Wear
When brake pads wear unevenly, one side might wear out faster. Uneven wear can lead to uneven pressure distribution on the rotor when braking. Over time, this uneven pressure can form grooves in areas experiencing higher friction levels.
The causes of uneven brake pad wear can be manifold, including poor quality pads, misaligned calipers, or a malfunctioning brake system component.
4. Malfunctioning Brake Caliper
The brake caliper squeezes the brake pads against the rotor to create friction. If a caliper is sticking or malfunctions, it can cause the brake pads to remain in constant contact with the rotor.
This continuous contact can generate excessive heat and wear, leading to the formation of grooves. A malfunctioning caliper might be due to various issues, including a failed caliper piston, corroded hardware, or degraded brake fluid.
5. Dry Guide Pins
The guide pins are responsible for guiding the proper angle for how the brake pad meets the rotor. These pins are usually lubricated to ensure seamless operation. However, this can be hindered if the pins become dry or corroded.
If this is the case, you’ll also want to ensure the rubber bushing isn’t damaged so moisture, dust, or debris can find their way in. Either way, the restricted movement can cause the brake pads to drag unevenly against the rotor, leading to grooves.
6. Rust or Lodged Debris
Rotors can develop a thin layer of rust when a car is left stationary for extended periods, especially in damp conditions. While this rust is typically scrubbed off the next time you brake, if it accumulates or becomes more substantial, it can cause grooves over time.
Additionally, small debris, such as tiny rocks or road particles, can also become trapped between the pad and the rotor. These particles can score the rotor’s surface as the wheel rotates, leading to grooves.
What Are the Consequences Of Grooved Rotors?
Before we go through how to address and determine the severity of the situation, we want to highlight some of the consequences of grooved rotors. This will give you an idea of how important it is that your brakes are in good condition.
Listed below are the most common consequences that grooved brake rotors can cause:
Uneven Brake Pad Wear
Uneven brake pad wear is a well-known consequence of bad rotors. Some areas of the pad may make better contact with the grooves, causing those spots to wear faster. This is why it’s recommended in some cases to replace the rotors while replacing the brake pads. If not, the brake pads will quickly take damage and wear down to the point where you’ll need to replace them again.
Reduced brake performance
In normal cases, a single groove or wear mark won’t significantly affect the overall brake performance. But over time, the grooves on the surface can become severe and disrupt the even contact between the brake pads and the rotor.
This can result in uneven braking force distribution and reduced friction, leading to longer stopping distances. This lack of efficient braking performance can increase the risk of accidents in emergencies.
Vibrations and Shaking
Another known consequence is vibrations or shaking when braking. When this happens, it means the brake pads aren’t making even contact all around, and as the rotor spins, the pads make contact with the high spots (areas without grooves) more than the low spots (areas with grooves). This difference in contact points generates vibrations.
These vibrations can then run through the braking and/or steering system, and if severe enough, you’ll likely feel it in the brake pedal or steering wheel as you apply the brakes.
Brake noise
Sometimes, you don’t feel the vibrations. Instead, you’ll hear a high-pitched squealing noise as the brake pads interact with the groves.
Furthermore, if your brake pads are worn to the point where metal comes in contact with metal, you’ll likely notice a more grinding noise instead. Either way, a squealing and grinding noise indicates that your brakes are in bad condition and need attention.
How to Address Grooved Brake Rotors
You probably already know or suspect your brakes are grooved as you are here. But before any corrective action can be taken, it’s crucial to identify the issue accurately. Here’s what to do:
Safety First
Park your vehicle on a flat surface and engage the parking brake. Make sure to let the brakes cool down.
If possible, you can examine the brakes through the wheel’s spokes, but we recommend removing the wheel for better vision. For this, you’ll need a lug wrench, a socket for your lug size, a car jack and a jack stand to secure the vehicle.
Inspect the rotors
With your wheel off and brakes cool enough, run your fingers over the surface of the rotor. Any noticeable grooves or rough patches indicate wear. Measure the rotor thickness using a brake rotor micrometer to determine if it meets the manufacturer’s specifications.
Determine Severity
If there are light groves, but the thickness of the brake rotor is within the manufacturer’s specifications, you can choose to resurface the rotors. If they are below the minimum thickness, it’s recommended to replace them instead.
Address the Cause
As there could be underlying issues, you’ll want to proceed by inspecting the brake pads and other brake components for wear and damage. Replacing the brake pads is also recommended if the grooved rotors are causing uneven wear. Whether you or a repair shop do the job, ensure the brake system is inspected and serviced.
Contact a Professional
Suppose you’re unsure about the condition of your rotors or how to address them; it’s best to have a trusted mechanic inspect your vehicle. They can provide guidance on whether to resurface or replace the rotors and offer additional recommendations.
Can I Keep Driving With Grooved Rotors?
Many drivers wonder if it’s OK to keep driving with grooved brake rotors. The short answer is yes, you can drive with grooved rotors, but it’s not ideal. While you still may have enough braking power, it will accelerate wear on your brake pads and possibly other braking components.
This means you can expect increased maintenance costs or other issues if the problem is not addressed. So before that happens, we recommend letting a mechanic look at the grooves to determine the best course of action. And as previously mentioned, if your rotors are still thick enough, you might get by with resurfacing them.
FAQs
Do I need to replace rotors with grooves?
If the grooves on your rotors are deep or exceed the manufacturer’s recommended specifications, it is generally recommended to replace the rotors. However, resurfacing the rotors may be a viable option if the grooves are shallow and within acceptable limits.
What happens if you don’t replace grooved rotors?
Neglecting to replace grooved rotors can result in diminished braking performance, increased wear on brake pads, brake noise, and potential overheating of the braking system. It is recommended to address grooves on rotors promptly to ensure safe braking.
Should rotors be perfectly smooth?
While rotors should ideally have a smooth surface, it is not always possible due to normal wear and tear. However, excessive grooves, scoring, or roughness can negatively impact braking performance and may require resurfacing or replacement.
How do I know if my rotors are ruined?
Signs of ruined rotors include excessive grooves, scoring, deep cracks, severe warping, or an uneven surface. Additionally, you may experience pulsation or vibration when applying the brakes, longer stopping distances, or brake noises.
