BRAKE ROTORS: WHEN SHOULD I REPLACE OR MACHINE/TURN?
You hit the brakes and feel vibrations or grinding. Huh, that's new. Plus, it's taking longer to come to a complete stop. These are common signs of bad rotors. So you take a look at your brakes and find that, indeed, your rotors are warping (causing shaking), too thin and are scorching your brakes or have ground out and looked like they have been chewed up. 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.
WHAT ARE THE PROS AND CONS, ACCORDING TO THE PROS?
The lowdown on resurfacing brake rotors, also known as cutting, machining, or turning rotors, drivers can usually make out better replacing their rotors over cutting them for a couple of reasons. Warranty and Performance
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 rotors cost significantly less than they used to accounting for inflation.
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 can however 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 (warp) that's causing those vibrations. When a rotor is machined, there is no warranty available. So if the cut, turn or machining damages or does not eliminate the warp of the rotor or damaged areas from grinding, you'll have to replace the rotor anyway and still be out the labor costs and have additional cost of the labor to replace the rotor and the cost of the new rotor.
When you resurface rotors, they're cut using the minimum specifications provided by the manufacturer, rotors at minimum specs are more likely to overheat, cause brake fade (feels like you have to press harder to stop than you did before), and cause delays in braking during an emergency situation. Resurfaced rotors are also thinner and most commonly warp more quickly and easier than before, causing them to lose brake efficiency.
When you replace rotors, however, they operate at maximum specifications for maximum performance.
Machined or turned rotors void manufacturer warranties and do not carry a warranty such as new rotors do.
4. MANUFACTURERS' RECOMMENDATIONS
Drivers of European makes like Volkswagen, BMW, Audi, and Porsche should know that manufacturers don't provide minimum specs for cutting their rotors because they do not offer this service as the service would degrade the safety of the vehicle. They recommend 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 about every 60,000 - 70,000 miles. This is the time frame that is the equivalent of how long a set of OEM Quality brake pads should last. Look for signs of uneven wear, excessive runout (warping, or shaking when you apply your brakes), and heavy pitting, spotting, grooving, hard spots, or cracking.