How Brake Rotors Work, and How to Tell if You Need New Ones

The components of your car’s brake system are among the vehicle’s most vital. If your brakes aren’t functioning correctly, you’re in danger whenever you get behind the wheel. You can say the same of your passengers and those around you.

The brake rotors are a part of that system. As a driver, it’s helpful to know how they work and when you might need new ones. Let’s take a minute to talk about that.

What Brake Rotors Are, and What They Look Like

There are several different rotor types. They include:

You can easily identify the rotor if you look at your car’s brake system. They are circular disks that connect to each of the vehicle’s wheels. There are two in the back and two in the front.

Rotors function through kinetic energy. They turn this energy into heat, also called thermal energy.

The calipers squeeze your brake pads together when you apply pressure. The large surface area then creates friction. Friction resists wheel spin, which slows the car till it can stop safely.

Without those rotors, your brakes won’t function.

More on the Different Rotor Types

Most vehicles operate with the blank and smooth rotor variety. These ones:

  • Have a blank, smooth metal surface
  • Work well for passenger vehicles

The drilled rotor variety has holes going around the metal’s surface. The slotted kind has long lines or surface slots.

The drilled and slotted variety has both slots and circular holes. These deliver enhanced vehicle performance.

Selecting the right vehicle rotor is not very challenging, because each one of these four looks distinct from the others. If you need to replace your rotors, though, and you’re not one hundred percent sure which ones you need, your local mechanic can certainly help you out in that area.

How to Tell if You Need New Brake Rotors

As for how you can tell when you’re wearing out your rotors, there are several potential warning signs. Using your ears when you’re out driving is the first and most obvious way.

Worn out brake rotors often make a squealing or squeaking noise. You might be a couple of blocks away, and you can still hear work out rotors when the driver applies the brakes.

What you really need to listen for, though, is grinding. That’s what comes after squealing, and it means that you’ve worn your rotors down. They make that noise when they are touching the metal, with no protection between them.


Another indicator is wobbling or vibration when you apply the brakes. This doesn’t so much mean that you’ve worn the rotors down. It is more an indication that you have warped or twisted them.

This can happen if there’s been a squealing noise for a while, and you’ve ignored it. Brakes get extremely hot when you apply them. The metal can warp over time, and vibration or wobbling means that good contact between the pads and rotors is no longer happening.

Anti-Lock Braking Systems

You might hear the term ABS, which means anti-lock braking systems. If your car has it, it’s particularly dangerous to allow your rotors to wear down to the metal. Luckily, this system will warn you if you’re getting close to that point.

In most cases, a light will come on the dashboard. Don’t ever ignore that light. If you do, you’ll have to get your rotors replaced, but you might need to get the sensor fixed as well.

Visual Evidence

You can also use your eyes to determine whether you need new brake rotors. You can see your car’s brake pads right through the wheels. When the vehicle is in park, turn the steering wheel to the far right or left.

Get out of the car and look from overhead at the wheels. You should have an unimpeded brake view. What you’re trying to see is the pad’s thickness.

You want to be able to see ¼ inch. If there’s less, then get the car inspected. You might have to replace those rotors or pads.

If you’re not sure about some of this, you can talk to your mechanic the next time you take the car for a tune-up. They will have no trouble showing you where the brake pads and rotors are.

They can show you precisely where you should look in the future if you need a visual indication that it’s time for new ones.   


Car Crash Aftermath: 5 Steps to Take Immediately After a Car Accident

How Brake Rotors Work, and How to Tell if You Need New Ones