How to Tell if Rotor is Bad (12 Symptoms & Replacement Cost)

When you’re driving down the road and press on the brake pedal you expect your vehicle to stop. It’s extremely important, but we often don’t think about all the components that go into this critical action.

The good news is that your vehicle has tons of ways of communicating with you if everything isn’t working the way it should. You just need to know what to look, listen, and feel for, which is why we came up with this guide to break down everything you need to know.

Not only that, but we’ll walk you through how often you should replace your rotors, how much you should expect to spend, and even what can happen if you put off the repair for too long!

How to Tell if Rotor is Bad – 12 Symptoms

Before we dive into how much it’s going to cost to fix or how to do it yourself, we need to confirm that there’s actually a problem with your vehicle’s rotors. Below we’ve highlighted the 12 symptoms that point you in the right direction on how to tell if you have a bad rotor.

1. Squealing/Grinding From Brakes

One of the first signs that something is going on with your brakes is that you’ll hear a squealing or a grinding sound. Sometimes you’ll only hear the noise when you apply the brakes and other times you’ll hear it whenever the vehicle is moving.

It all comes down to the exact problem with your rotor but squealing and grinding noises are often the first sign. Squealing and grinding noises can indicate a ton of potential problems with your brakes though, so you can’t jump straight to a rotor replacement.

Related: New Brakes Squeaking – What It Means, Causes & How to Fix It

2. Large Edge On the Outer Part of the Rotor

This isn’t a symptom you’ll likely notice while driving, but whenever you replace the rotors, you need to take a hard look at the edge of the rotor. This groove shows you how far the brake pads have worn down the rotor since the last time you either resurfaced or replaced the rotors.

Rotors can only get so thin before you need to replace them, and just like the brake pad wears down, the rotor does too. Once the rotor gets past its minimum thickness, you can’t resurface it during the next brake pad replacement, and you need to replace the rotors too.

3. Vibrations When Braking

When you hit the brakes, your vehicle should smoothly stop. If you hit the brakes and your vehicle vibrates in the brake pedals or steering wheel, that’s a sign of a problem.

Just like a squealing or grinding sound, vibrations simply indicate there is a problem somewhere in the brakes. It could be the rotors, but it could also be the pads, calipers, or something else entirely.

4. Grooves or Scores on the Rotor

If you’re trying to figure out if your vehicle’s rotor is in good shape, one of the easiest things you can do to figure out if the rotor is in good shape is to look at it.

Wait until the rotor cools down, then run your fingers over it. If you feel deep grooves throughout the rotor, it’s time to replace them. This process is also known as scoring, and it’s a sign that it’s time to replace the brake pads too. Replace both the pads and the rotors on the axle and you should be good to go.

5. Scratched Rotor

While there are a few different conditions that can lead to scratched rotors, no matter what’s causing it, you’ll need to replace the rotors.

Address the root cause of the scratches, usually faulty or worn pads, and then replace the rotors. Scratched rotors might not seem like much, but the brake pads can’t get all the necessary friction, leading to reduced braking power.

6. Glazed Rotors

If the rotors exceed their rated temperature when they cool back down, they can form a glaze over the rotors that keep your vehicle from stopping as effectively as it should.

The good news is that most of the time, you don’t need to replace glazed rotors. Safely get a few hard highway stops in and you should be able to work that glaze off the rotors. But if the glaze is too thick or you don’t feel comfortable working it off the rotors, you can replace them to fix the problem too.

Finally, if you have a glaze on the rotors, check out the pads too. They will often glaze over too, and sometimes, even crack.

7. Out of Round Rotors

When you look at the rotors from the side, you should see that they form a perfectly flat circle. However, if the brake rotors heat up more than they should, they can warp.

When the rotors warp, they get “out of round,” which means they’re no longer flat when you look at them from the side. And when you’re driving, this causes the rotor to sit at different spots against the brake pads, and it’s terrible for braking performance.

Not only will it cause stopping problems, but it will also wear down and damage other components.

8. Pulsing Brake Pedal

If you can’t get a good view of your brake rotors, pulsing in the brake pedal is what you’ll typically feel if the brakes are out of round. However, if the out-of-round isn’t severe enough, you might not be able to feel the difference unless you know what you’re looking for.

The pulsing occurs when the pads move around to accommodate the different positions of the caliper and brake pads that shift because of the moving rotor.

9. Loud Noises When Braking

When you hit the brakes, it should be a relatively quiet experience. So, if you hear a loud bang, clunk, or any other sort of loud noise when you hit the brakes, you need to figure out what’s going on.

It could be the rotors cracking, shifting, or a variety of problems. Don’t just ignore the loud noises; it’s a clear-cut sign that something is wrong.

10. Longer Stopping Distances

If there’s a problem with your vehicle’s rotors, there’s a good chance it will affect how effectively your vehicle can stop. That’s what they’re on your vehicle for, so if they’re not working right, that’s where you should expect problems.

This is especially true if the rotors have scratches, scoring, grooves, glazed, or if they’re out of round. It’s also why it’s so important to replace the rotors as soon as you start noticing a problem. The last thing you want is to get into an accident because your brakes aren’t working the way they should.

11. Excessive Corrosion

It’s important to note that the keyword here is excessive. A little bit of corrosion on your brakes can be normal, especially if you haven’t driven your vehicle in a while.

A few miles on the road should wear that corrosion off and leave you with shiny brakes where the pads sit. However, excessive corrosion isn’t that simple. When it wears off, it can leave uneven rotors, or even worse, it can leave holes in the rotor.

In general, corrosion on your brakes is bad, so if you notice a lot of corrosion around them, it’s a problem you’ll want to address sooner rather than later.

12. Cracked Rotors

This is by far the worst-case scenario, and if you have cracked rotors, you should not drive your vehicle anywhere until you fix it – this includes the repair shop. If you notice cracks along the rotor, it’s only a matter of time until they fail completely, and when that happens, you might not be able to stop your vehicle at all.

There’s also a good chance if your vehicle has cracked rotors, there’s further damage there too. Finally, this is why you need to replace rotors after they reach a minimum thickness.

Cost to Replace Your Rotors

If you’re taking your vehicle to a professional repair shop for new brake rotors, you should expect to spend between $350 and $500 per axle.

Some estimates will come in lower, but they won’t account for the cost of replacing the brake pads. The pads mate to the rotor, so it’s essential if you’re replacing the rotors, you replace the pads too.

Furthermore, when replacing your rotors and pads, you need to replace both sides of the axle at the same time. Otherwise, you won’t have even or consistent braking and your vehicle will pull to one side when trying to stop.

The good news is that about $150 of this cost comes down to labor. That means if you’re looking to cut the cost a bit and don’t mind doing the work, you can get the cost down to between $200 and $350. It’s still a pricier job, but savings are savings!

What Happens If You Don’t Replace Your Rotors?

While you might not want to spend the money to replace your rotors, it’s not a repair you want to put off. Not only is it unsafe since your vehicle might not stop as effectively as it should, but it can also lead to far more expensive damages.

That’s because as the rotors wear down or warp, it can lead to further damage throughout the rest of the components in your brake system. For instance, if the pads wear down to the metal it will damage the rotors and eventually the calipers.

Damaged rotors can lead to the pads wearing down faster than they should and can cause them to overheat and even crack.

In a worst-case scenario, the rotors will crack and fall apart on you while you’re driving, making it impossible for you to stop. This can lead to an accident, serious injury, or even death. So, take care of your brakes so they can take care of you!

How Often Should You Replace Your Rotors?

With so many shady mechanics and dealerships out there, this can be a question that is hard to find a straight answer to. We understand and don’t want you to get ripped off, which is why we wanted to give you a breakdown of the truth behind the matter here.

A lot of factors go into this, but generally, you should expect your rotors to last between 30,000 and 70,000 miles, and sometimes they can last even longer than that!

A big factor that goes into it is how you drive your vehicle. If your rotors only last about 30,000 miles, it’s either because you have low-quality rotors or because you drive your vehicle extremely aggressively. Think of a car that you’re constantly taking to the track where the brakes constantly heat up and cool back down.

For most driving conditions, your rotors should easily last at least 50,000 miles and most will last closer to the 70,000-mile mark.

Anytime you replace the brake pads, you should either replace or resurface the rotors. However, there’s one big caveat to this. Just because you don’t need to replace the rotors doesn’t mean you don’t need to service the rotors.

The pads mate specifically to the rotors, and if it doesn’t have a smooth surface to mate to, you won’t get the best possible performance when you hit the brakes.

Finally, if you have any questions about how long your rotors or pads should last, refer to your vehicle’s owner’s manual for the maintenance schedule. This will give you a good idea of what to expect as long as you’re using OEM parts.

Final Thoughts

Now that you know to tell if your rotor is bad, it’s up to you to keep an eye out for the warning signs and address them right away if something comes up.

While it might seem like magic that your vehicle stops every time you press the brakes, there are a lot of mechanical components that go into it. Keep up with the maintenance and it will keep working like magic, but if you don’t, you might find yourself dealing with more expensive repairs or even an accident.

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Rickard Cefalk

Rickard is the owner of and a dedicated and avid do-it-yourselfer who has always enjoyed working on his own vehicles since childhood. He now devotes his time to sharing his expert knowledge of car maintenance and other car-related information through his website.

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