If you’ve put significant mileage on a single car, you’ve undoubtedly heard the irritating squeal from the brakes indicating that the brake pads have worn to the minimum allowable thickness and it’s time to complete some brake system maintenance. When your pads wear, you only have one option, which is to replace them. However, when it comes to brake rotors, you have the option to replace them outright or turn them down to resurface them. One question we are often asked is how do you know if you should replace or turn the brake rotors when performing brake work? To answer this question, we briefly summarize the advantages and disadvantages of each option below.
Turning Brake Rotors
To turn a rotor, a mechanic will start by removing your rotor from the car and measuring it’s thickness with a caliper or a micrometer. They will then calculate how much material they need to remove and make sure that once the rotor has been turned, it still meets the minimum thickness specification set by the vehicle manufacturer. Assuming the rotor will still meet spec, it is attached to a lathe via the center bore and then a small tip is run across the surface on each side to remove a small amount of material in order to rid the surface of waviness. This will also remove any lip that exists on the outer diameter of the rotor. The cost of the machine work, whether completed by your local auto parts store or a dedicated machine shop, can vary but since you are paying for someone’s time it can still add up to turn four rotors. The benefit to this of course is that you can reuse your old rotors after they have been turned down and don’t have to pay the cost of brand new ones.
While the cost of the work can seem small, you also have to take into account the time to transport the rotors to the auto parts store or machine shop. You can decide to wait on the spot for the work to be completed, or perhaps you will need to drop them off and return later to pick them up. Depending on your timeframe and car situation (remember, you can’t drive your car to the shop if it has no brakes) this can potentially be a pretty big hassle. Beyond transportation, you also need to remember that the thinner the rotor is, the faster it heats up if you drive with a heavy foot which makes this option less ideal for “spirited” drivers due to potential brake fade considerations (although the differences are slight).
Replacing Brake Rotors
Replacing the brake rotors is likely the more pricey option by a bit when it comes to pure dollars, but when you consider the added simplicity and convenience the economics start to make more sense. Assuming you ordered ahead online and had the parts delivered, it’s pretty easy to get a new set of rotors without much wait time.
The main drawback with a new set of rotors is the cost. Buying new will most likely exceed the cost of simply turning the rotors, but an advantage to new rotors is that their higher thickness serves to generally slow the heat absorption during braking which can make brakes slightly less prone to fade if you are heavy on the pedal for extended time. New rotors simply need to be cleaned with brake cleaner, allowed to dry, then installed to your vehicle.
When comparing the total cost of turning the rotors against the purchase price for new brake rotors, new rotors tend to come in a little but higher pricewise but with significant added convenience. In either case, the rest of the brake job is the same. You still have to break out your lug wrench and remove your wheels, remove and reinstall the calipers, remove and reinstall the rotors, swap the pads (using a caliper wind back tool if you want to make life easy), and bleed the brakes. Ultimately, it will be up to you to decide if the cost savings of turned rotors justifies the extra headache involved and whether their reduced thickness will add additional headaches from potential brake fade issues.
On a final note, there is no better time to do a brake fluid flush than when swapping your brake components, so before starting your brake job we recommend testing your brake fluid to see if it needs to be replaced! Happy wrenching!