Why Do Brake Rotors Warp?

Brake rotors are the large metal discs visible behind the wheels of a car. These spin along with the wheels so that when the brake pads clamp down on them, they stop the car. Brake discs have to withstand a tremendous amount of heat. Not only that, they have to dissipate that heat into the air as quickly as possible because the brakes will probably be pressed down again in a short amount time. If the surface of the disc becomes uneven over time, braking will become jittery and less effective. This is usually referred to as warping.

How brake rotors warp

A common misconception when rotors are referred to as “warped” is that they are no longer straight when rotating (similar to how a bicycle wheel gets warped). For cars, in order for that to be the case, the rotors themselves would have to be defective as the temperature required to make metal that resilient soft enough to simply bend would be tremendous.

Instead, the warping really refers to the flat surface of the rotor becoming uneven. Heat is the number one cause of this, and can cause warping in more than one way:

  • Glazing the brake rotor with material from the brake pad. This happens because brake pads, like tires, are made with different amounts of hardness and stickiness depending on the intended purpose. When brake pads made for normal road use get very hot from high-speed driving and braking, or from riding on the brakes for a prolonged period of time, the grippy material can get too soft and basically "paint" the brake rotors. This means that the brake pads won't grip onto metal when the brakes are applied once again, causing decreased brake performance that is less smooth than before.

  • Wearing down the surface of the rotor and making harder spots in the metal stay slightly raised off the surface. The reason that brakes don't normally wear down very much revolves around a fairly straightforward concept. Since the metal of the rotor is harder than the brake pad applying friction to it, the pad wears down while the rotor remains largely unaffected. With excessive heat, the metal becomes soft enough for the pad to wear down the rotor surface. This means that slightly less dense spots in the metal wear down faster and make the harder spots stick out, causing warping.

How to prevent warped brake rotors

To prevent the brake rotors from becoming glazed over with brake pad material, be mindful of how much braking the vehicle is doing compared to what is done during normal operation. When going downhill for prolonged amounts of time, try to control the speed of the vehicle by shifting the transmission into a lower gear. For automatics, the only option is usually to shift into "3," while vehicles with a manual or other shiftable transmission can decide on the best gear to use based on the engine's revs. When the brakes are hot, never sit with the brake pedal hard down on one spot.

Also, when the brake pads are first installed they should be properly broken in to ensure they don't leave too much material on the brake rotor. This usually involves getting the car up to road speed and then braking until it is traveling ten miles per hour slower. After this is done a few times, you can work your way up to braking to a complete stop. The first few full stops after that should be done with care. This allows the brake pad to perform better during hard braking further down the road.

The steps that can be taken to prevent excess wear on the surface of the brake rotor are similar to the steps for avoiding glazed rotors. Be sure to avoid hard braking when the brake rotors have gotten hot from prolonged use.

What do warped rotors feel like?

There are a few symptoms to look for when it comes to diagnosing warped rotors:

  • If the brake rotors are glazed over, you may hear excessive squeaking when the brakes are applied or even smell burning rubber.

  • If the braking suddenly becomes jittery and inconsistent, the brake rotors should be the first suspect.

  • If the vehicle vibrates when coming to a stop, the brake rotor is likely warped.


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Recent Brake Rotors/Discs Replacement reviews

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3,049
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Tinashe

13 years of experience
605 reviews
Tinashe
13 years of experience
Toyota Camry L4-2.4L - Brake Rotor/Disc Replacement (Front) - Ellenwood, Georgia
He is soooo awesome super understanding I was very satisfied with this gentleman, honestly trustworthy and very knowledgeable and informative. I will be using him again in the future
BMW 750Li xDrive - Brake Rotor/Disc Replacement (Front, Rear) - Woodstock, Georgia
Tinashe showed early and immediately went to work on my car. He did a great job and worked fairly fast in the scorching heat. The job was fantastic. A by the way, I'd seen how the job is done on YouTube, so I had different expectations in the process from his approach. Overall great job! I would definitely have him work on my car again and he comes highly recommended. Great job Tinashe!

Mathew

6 years of experience
54 reviews
Mathew
6 years of experience
BMW 528i xDrive L4-2.0L Turbo - Brake Rotor/Disc Replacement (Rear) - Philadelphia, Pennsylvania
Amazing tech and great overall person. He really went out of his way to make sure my car was in tip top shape. I messed up the appointment and mathew still made it work. Best bmw tech on the road!!! im will be booking again and telling anyone who needs a great tech!!!
Hyundai Santa Fe - Brake Rotor/Disc Replacement (Rear) - Philadelphia, Pennsylvania
Matt was GREAT! He was on time and he solved the problem with my vehicle. Matt gets the job done. I already booked my next appointment. Thanks Matt.

Pierre

9 years of experience
308 reviews
Pierre
9 years of experience
Buick LaCrosse V6-3.6L - Brake Rotor/Disc Replacement (Front) - Brockton, Massachusetts
Pierre was very professional, polite, very friendly and respectful. He IA very knowledgeable about his job and the tasks put in front of him. I feel extremely confident with his labor in repairing the issue of my car
Toyota Corolla - Brake Rotor/Disc Replacement (Rear) - Brockton, Massachusetts
This guy isn't just friendly and outgoing and very knowledgeable. He goes out of his way to go beyond help you may need. I want to thank him for a great service and more to come.

Luis

29 years of experience
91 reviews
Luis
29 years of experience
Infiniti QX60 L4-2.5L Turbo Hybrid - Brake Rotor/Disc Replacement (Front) - Chicago, Illinois
very professional, arrived on time, work done within the time frame, very polite, and excellent job done!!!
Saturn Ion - Brake Rotor/Disc Replacement (Front) - Des Plaines, Illinois
Arrived early, finished quickly and let me know about future maintenance I might need. Excellent mechanic

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