Brake Rotors: When to Fix and When to Buy

brake rotor
You hit the brakes and feel vibrations. Huh, that's new. Plus, it's taking longer to come to a complete stop. You know these are common signs of bad rotors. So you take a look at your brakes and find that, indeed, your rotors are warping.

You're all about using quality parts, but you're also wondering if you could resurface your rotors and make them stretch a few more thousand miles. Before you make your decision, here's what you need to know about when to replace brake rotors and when to resurface them.

The pros and cons, according to the pros

To get the lowdown on resurfacing brake rotors, also known as cutting, machining, or turning rotors, we talked to master tech Adam Hogan. He has nearly 20 years of experience in the field and owns a shop in the snow belt of Maine.

Hogan says that in the South, resurfacing is more common than in the North, where the minerals used on the roads to melt ice corrode the rotors more quickly. Even in the Southern states, however, where salt isn't as much of an issue, Hogan says drivers can usually make out better replacing their rotors over cutting them for a couple of reasons.

1. Improved technology

Back in the day, resurfacing rotors just made sense, because rotors were expensive. But the technology has changed dramatically. Manufacturers have separated the rotor from the hub and are using lighter, less expensive materials. Today, drivers can pick up a hubless rotor for less than $50.

2. Lower cost

You might think that shaving some metal off the rotor has to be cheaper than the rotor replacement cost. The labor costs for turning the rotor, however, may exceed the price of a new rotor. You also run the risk of the shop cutting a warped rotor to the manufacturer's minimum specs without eliminating the lateral runout that's causing those vibrations. Then you'll have to replace the rotor anyway and still be out the labor costs from machining.

3. Safety

When you resurface rotors, they're cut using the minimum specifications provided by the manufacturer. Rotors at minimum specs are more likely to overheat, give brake fade, and cause delays in braking during an emergency situation. Resurfaced rotors are also thinner and might warp more quickly, causing them to lose brake efficiency.

When you replace rotors, however, they operate at maximum specifications for maximum performance.

4. Manufacturers' recommendations

Drivers of European makes like Volkswagen and BMW should know that manufacturers don't provide minimum specs for cutting their rotors. They recommend a replacement every time. Many shops will also advise against resurfacing captive rotors on vehicles like a Chevy Colorado because labor costs can exceed the value of the part.

That may sound like a lot of cons and not a lot of pros. So when is it a good idea to resurface rotors?

Some people might want to machine rotors on vehicles with uneven wear patterns, for example, when one rotor needs to be replaced but the other rotors show minimal wear. In most cases, however, it's best to replace rotors in pairs to ensure even braking that doesn't pull to one side. Machining can also remove unsightly surface rust and restore rotors that are otherwise in good condition.

How often do rotors need to be replaced?

Even if you resurface your rotors to keep them in good working order, you'll generally need to replace them by 70,000 miles. Look for signs of uneven wear, excessive runout, and heavy pitting, spotting, grooving, hard spots, or cracking. Still want to save some money? Purchase rotors, avoiding the shop's markup, and either replace them yourself (here's how) or take them to a trusted technician.

Got any other tips for how to tell when brake rotors need to be replaced? Share the knowledge in the comments.

Last updated June 6, 2018