When Does It Make Sense To Change Brake Rotors?

Example Of A Bad Brake Rotor

What Brake Rotors Do

A Brake rotor is a circular piece of metal that sits in between the brake calipers in your wheel structure and rotates on the focus (centre) along with the wheel. Its main function is to serve as a base for the brake calipers and brake pads to grip when the driver desires to slow down or stop the vehicle. The brake pads clamp onto the rotor, causing friction which transforms the kinetic energy from the wheel into thermal (heat) energy. The brake rotor is designed to disperse this heat energy so that no single part gets too hot. The quality of a rotor is based on a number of performance factors, such as:

  • How resistant to cracking the rotor is during the continuous heating up and cooling down cycle
  • The diameter, which factors into the mechanical advantage
  • How efficient the rotor is at dispersing the heat energy that it is absorbing from the friction between it and the brake pads
  • The weight of the rotor (lighter is usually better but only if it performs just as good as a heavier rotor under the same conditions)

When You Should Change Brake Rotors

How often you should change brake rotors is usually a question that mechanics sometimes disagree on. Usually, the idea is that you should never have to routinely change your rotors unless they have endured some sort of damage that affects their performance. If the rotors are indeed, damaged, the most likely cause is because of worn out brake pads. Sometimes, when you continue to drive you vehicle for an extended number of miles with extremely old brake pads, the rotors will get damaged by the screws in the brake pads that have been exposed because of the wear. This usually makes an unpleasant grinding noise when you depress the brake pedal that stems from the screws rubbing against the grooves in the rotor.

However, if you change your brake pads as soon as they show signs of being worn down, then you should theoretically never have to change brake rotors. Be wary of some scams that particular repair shops run where they offer life-time warranty on brake pads but will magically find something else wrong with the car when you try to come in for your free replacement. Midas is one such company that I have personal experience with – I went in to claim my free brake pad replacement (from the warranty) and the guy told me that I also needed the rotors to be replaced. I told him I only wanted to change the brake pads and he said it was against their policy to replace the brake pads while the rotors were in an unsuitable condition. So, I went ahead and had the work done for the rotors and the brakes and when I returned to pick up my vehicle I requested to also take the old rotors with me. The mechanic was extremely hesitant and I know why – turns out my rotors with still in decent condition (obviously not brand new) and that they didn’t need to be replaced in order for the brake system to function properly. I showed the rotors to two different mechanics that I trust and they both agreed that I was ripped off.

So, what’s the moral of the story? Change your brake pads often so that you don’t ever have to change your rotors, but if you need new rotors, do it at a shop that you trust!

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Comments 5 comments

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Auto Tech 6 years ago from Kentucky

I am an ASE technician and read your hub. Working in the autorepair field I have seen many things. Most shops don't like to just replace pads because it is important to make sure the rotor is resurfaced or replaced due to normal wear. Pad slapping is not recommended if you want your brakes fixed right. Glazed, slick rotors will glaze pads and cause brake noise in the form of a squeek, not always, but more than not. As rotors wear they get thinner and have less ability to disipate heat which will create brake fade. You will have a nice hard pedal, but your vehicle will not stop as fast as it did from the factory. This is a fact. Many people try to put off the repair cost of a vehicle by saying the mechanic tried to cheat me. No, he was just trying to fix your car the right way. Remember,you get what youpay for. Please, don't stereotype not all mechanics or shops are crooks. Auto repair done right can be expensive, but will save you money in the long run. I agree that there are some shady people in the world. This man should have offered to turn(resurface) your old rotors. Love to talk cars. Questions are welcomed. Good Hub


Los 5 years ago

I just happened to stopped by at a Midas yesterday for an oil change. Typically I do it myself but I was in the area and had time to kill plus they offered a visual inspection of my rotors and brakes… I have a 2001 Hyundai elantra.

I was told that

A) pads and rotors had to be changed

B) reshaping of the rotors was not recommended but they would do it anyway if I wanted… but they would not be responsible for lack of performance or noise

C) the job would be $800 bucks for new rotors and pads.

Now I have only owned the car for 5 years and one of the first things I did to it was change the factory rotors. It was needed just something I wanted to do. My driving is moderate at best… about 1000 – 2000 miles a year and I take care of the vehicle.

When I asked how much would it be for just the break pads the guy would not give me a price because they wouldn’t do the work unless I had them work on the rotors as well…

What bothered me about this whole thing was that they would do work on the rotors in reshaping them but not stand by their work which just made it seem as if they were only interested in trying to make more money.

I decided to go to another mechanic that I have been to a few times before and he felt that the rotors were just fine and didn’t require any reshaping. The pads he did feel I should attend to soon. For the heck of it, I asked if he could give me a quote on new rotors and pads. The brands he would use I felt were better and the warranties were similar but his quote was over $300 less…

So get those second options every single time…


Frank 4 years ago

This article does confirm when a rotor really should be swapped out...

http://www.cquence.net/blog/changing_brake_rotors/

It says a rotor needs to be replaced when there is certain level of structural damage such as a cracking or groves from the brake pad screws, not just because your changing your brake pads! As long as the rotor has at least it's recommended minimum thickness, and is not damaged, then the rotor is good for more miles.

The whole thing with mechanics asking you to change the rotors out with the pads is a way to make more money.


pomysean 3 years ago

What a great information, I think it is very helpful information about time of changing the brake pads. Good and keep it up. See and visit different types of centric brake pads on Autoplicity.

http://autoplicity.com/manufacturer/1394-centric-b...


john 2 years ago

great post

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