ASC Admin May 1, 2015

What are rotors

RotorA rotor, also called a disc brake, is a type of braking system that works in conjunction with the brake pads creating resistance to decelerate the rotation or keep the shaft immobile. To achieve this resistance, brake pads are mounted onto the vehicles brake caliper to forcibly press down on the rotor to cause the friction used to stop. This can happen mechanically, pneumatically, hydraulically, or electromagnetically. Waste heat is created by the circulation of the vehicles wheels and must be discharged to avoid overheating, also known as brake fade.

How do rotors work

The brake disk is typically made from cast iron and the designs can vary. Some are solid, some are hollowed out to create “ventilation”, some have holes drilled in them and some are slotted. Solid brake discs are ideal for standard vehicles while ventilated rotors are ideal for more-heavily-loaded front discs. The practice of drilling holes through the rotors is called cross-drilling and is usually used in higher-performing brakes. Though originally made for race cars, cross-drilling is no longer considered the optimal choice for them. Slotted brake disks are now used for racing cars since the slots allow the shallow channels (created by the slots) to remove water, dust, and gas.

How to maintain rotors


Once you have the ideal braking system for your vehicle, maintaining the upkeep is just as important. Routinely check the brake fluid. Change your brake fluid if it becomes a milky color because this means your system has been contaminated by water or condensation. Leaving your brake fluid alone can weaken your wheel cylinders and ultimately destroy your master cylinder. Bleeding your brakes is another step in keeping your braking system functioning. Bleeding the brakes usually requires two people. One person will need to pump the brakes to get all the air out of them while the other will need to watch the bleeder valve until fluid starts to leak out. Physically inspect your brake pads. If worn to the point that there is little padding left, they will need to be changed.

When to change your rotors vs when to resurface your rotors

Changing rotors

You’ll need to change your rotors when or if you can feel/see deep grooves or you feel shuddering when braking. To change them yourself, you’ll need to remove the calipers then remove the brake rotor. Give your rotors a new coat of brake cleaner to avoid moisture, grime, and dust and re-install the caliper. Ensure your new rotor is working properly before driving on the roadway. The average cost of replacing the rotors yourself is between $60 and $90. To have a mechanic change your rotors, the cost can be $350-$600.

To resurface

A professional needs to resurface rotors since they have the machine to make them like new again. Time and labor can cost $183-$242. The cost to replace your rotors is between $43 and $113 each. The front two rotors typically fall into the price range of $65-$113 each while the rear rotors fall between $43-$92 each.