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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