Blog Car Care Advice What Causes a Warped Rotor? (+Symptoms and FAQs)
Car Care Advice

What Causes a Warped Rotor? (+Symptoms and FAQs)

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Your disc brakes have rotors that are round discs you may be able to see through the spaces in your rim. They withstand a lot of heat when you use your braking system. This heat must quickly disperse so the brake pads can press down again.

But what happens when the heat doesn’t disperse well?
Too much heat can make your rotor surface uneven over time. That’s what warping is – an uneven rotor surface. 

However, heat isn’t the only reason rotors wear out irregularly.

In this article, we’ll explore eight causes of a warped rotor, four symptoms of a warped rotor, and discuss four rotor-related FAQs.

This Article Contains:

Let’s get started.

8 Causes of a Warped Rotor

Here are the usual suspects behind brake rotor warping:

1. Excessive Heat

Excessive heat is the most common cause of a warped brake rotor. Usually, if you press the brake pedal, your brake pads clamp down on the rotor. 

What does this do? 
It creates friction that slows down your wheels and stops your car. This friction generates heat, which can cause the rotor to warp if it becomes too hot.

2. Improper Maintenance

Improper maintenance can also warp brake rotors, so you should regularly check your vehicle’s brake pads and rotors for wear. Thin and worn brake pads may not be able to dissipate heat properly, causing hard spots and brake rotor warping.

Why else is proper maintenance necessary?

Well, brake fluid (from a leak) and debris can build up on your rotor if you don’t regularly clean your vehicle’s brake system using a good brake cleaner, causing it to warp.

3. Hard Braking

Another common cause of warped brake rotors is hard braking. If you’re constantly braking hard or experience stop-and-go traffic a lot, the excessive heat and friction may cause hard spots and lead to warped rotors. Hard braking also contributes to brake fade

Note: Brake fade can be prevented by regularly flushing your brake fluid as it reduces moisture contamination.  

4. Driving on Rough Roads

Driving on rough roads exposes your rotors to obstacles that stress them, like potholes and speed bumps. This can cause them to warp over time.

5. Manufacturing Defects 

Brake rotors can also warp due to manufacturing defects. If the rotors are faulty and paired with low-quality brake pad material, they’ll be more susceptible to warping due to heat and stress.

6. Glaze

The design of the brake pads’ friction material allows it to withstand a lot of heat. However, high-speed driving or riding the brakes can cause your pad material to get too hot. The friction material then loosens up and coats the rotors.

This results in a soft mirror-like glaze on the braking surface of your rotors, reducing the stopping power of your brake system

Avoid hard driving and stopping at a light with your foot on the brake. These actions cause glaze to be deposited unevenly across the rotor face, making the rotors feel warped.

7. Malfunctioning Brake Calipers

The brake caliper squeezes your rotor with brake pads. 

As such, a malfunctioning brake caliper can put too much stress on an overheated brake rotor if it exerts too much force — causing it to go off-balance and leaving you with warped rotors. 

8. Damaged Wheel Bearing

If you’re experiencing a wobble, but your wheels aren’t bent, it’s most likely due to a worn-out wheel bearing. A faulty wheel bearing can lead to warped rotors, irregular brake pad wear, and even more severe issues. 

Faulty wheel bearings can even deform the mounting face of a wheel hub to the point where the rotor on the hub will warp and show excessive runout.

Now that we know how rotors become warped, let’s look at how to identify if we’re dealing with warped brake rotors.

4 Symptoms of a Warped Rotor

Here are a few things to look for when identifying a warped rotor:  

1. Brake Pedal Pulsation  

Brake pedal pulsation is the most common sign of a warped brake rotor. You’ll feel the pedal pulsation through the brake pedals when applying pressure. Sometimes, even a light pedal pressure on the brakes can cause pulsations.

2. Vibration from Your Steering Wheel

Your brake rotors and calipers are attached to the same spindle as your wheels. Therefore, vibrations from warped brake rotors can move through the brake calipers to your wheels and steering wheel.

3. Noises from Your Brakes

There are certain cases where you’ll hear noises coming from your brake rotors upon braking. 

These noises happen because your brake rotors touch your brake pads at irregular intervals due to an uneven rotor surface. You might hear a low-pitched groaning or a rhythmic thumping sound. 

4. Vehicle Pulls to One Side

Rotor lateral runout is how much the brake rotor varies from side to side when viewed from the front edge. It’s also called axial or lateral runout. 

The runout creates a wobble during tire rotation. Uneven rotor wear caused by excessive runout can produce vibrations when braking. In extreme cases, your vehicle may pull to the right or left side while stopping, which can be extremely dangerous in heavy traffic.

It’s easy to identify a problem with your braking system once you know what to look for. 
Let’s head over to some burning questions about warped brake rotors.

4 Warped Rotor FAQs

Here are four frequently asked questions about a warped rotor, and their answers: 

1. Can I Drive With a Warped Rotor? 

It’s not advisable.

Any condition that affects your brakes can be dangerous. Warped rotors can degrade the braking efficiency of your car, causing longer stopping distances which could end in an unfortunate mishap.

Pulsating during deceleration shouldn’t be taken lightly, as it increases wear on your steering and suspension systems. And a worn rotor can accumulate more wear over time, increasing the repair cost.

Additionally, your brakes can become jittery and less effective. What happens is that excessive lateral runout of the rotor face causes them to become irregular. Even 0.002″ of lateral runout (that’s smaller than you can see), you’ll still be able to feel it through the brake pedal. 

So, if you notice anything funky while braking, contact your auto repair shop or mechanic ASAP.

2. How Much Does it Cost to Replace a Warped Rotor?

Replacing a brake disc may cost you between $200 to $400 for parts alone, and additional labor could cost an additional $150. A brake rotor replacement job for a new rotor can cost around $400 to $500

Note: Choosing Original Equipment Manufacturer parts (OEM pads or rotors) for a replacement has many advantages, as they’re made to fit your vehicle and are quiet on application. In fact, using OEM pads will ensure your replacement rotor isn’t damaged that much during its lifecycle. 

3. What is a Brake Pad Deposit?

Brake pad deposit is the substance your brake pads emit under high temperatures. It then transfers onto the rotor surface. Pad deposit can cause vibration, pedal pulsation, and hot spots on the rotor’s surface, resulting in thermal cracks or premature brake failure.

Although pad deposit does not come from a bad rotor, it can cause your rotor to fail. 

4. Can a Warped Rotor be Fixed?

Depending on the rotor condition, you could opt for a rotor replacement or ask your mechanic about resurfacing rotors

Thick warped rotors can be turned in a machining process that uses a lathe to smooth the bad rotor. Unfortunately, since your rotor is a stressed metal, a worn rotor can eventually return to its old, warped form, and you’ll need a replacement rotor.

Final Thoughts

It’s important to note that a warped rotor is just a rotor with an uneven surface — the rotor itself has not become all bendy. However, this irregularity can cause brake failure and shouldn’t be taken lightly.

So, if you’re experiencing issues with your brakes or need other fixes (like a battery change or transmission repair), contact the best mobile mechanics, AutoNation Mobile Service

AutoNation Mobile Service technicians are available seven days a week, and you can easily book via our online booking system. All auto repair services come with upfront pricing and a 12-month | 12,000-mile warranty.