Turning Brake Rotors vs Replacing

Last Updated on July 31, 2020 by Tim

If you’re considering performing maintenance on the brakes of your car yourself, you probably already understand two critical truths: Properly functioning brakes are critical and DIY brake maintenance saves a ton of money.

Although saving money is the primary objective, no one wants to risk death for the sake of a few bucks. In the ongoing debate over turning rotors versus getting new ones, any argument presented essentially comes down to balancing the weight assigned to safety and the weight given to cost.

The more risk averse among us will argue that any compromise to performance is not worth the risk, while the more reckless among us may argue that turning isn’t necessary at all. When weighing your position on this topic, it is important to consider your personal resources and values.

When should brake rotors be RESURFACED?

Ideally, resurfacing (also called “turning” or “cutting”) brake rotors should be done whenever the brake pads are changed. Just as basketball shoes don’t work well on a sandy basketball court, new brake pads can’t perform to their best when used in conjunction with oxidized, rutted, and marred rotors.

However, most will agree that turning at each brake service is overkill for most drivers with most cars. A better guideline would be to have rotors resurfaced every other brake change. Anytime the brake pads have been allowed to wear down to the wear indicator causing an audible squeal under braking, the rotors should be resurfaced and inspected.

When should brake rotors be REPLACED?

While some will argue that rotors should be replaced with every brake job, there are certain scenarios in which everyone will agree that replacement is necessary. Rotors should definitely be replaced whenever there is any type of damage to the rotor.

Cracks, dents, excessive warping, and excessive corrosion are common conditions that will make replacement mandatory. Otherwise, rotors can last thousands of miles without need for replacement.

Replacing can be done by just about anyone. Simply go to your local auto parts store or online to purchase new rotors compatible with your vehicle. Then all you’ll need is a floor jack, pair of jack stands, lug wrench or impact wrench, wheel chocks, and a couple other tools to remove the brake caliper and rotor.

Where can I get my rotors turned?

When you’ve determined that your rotors should be turned and not replaced, there are a few places to turn to that specialize in this service. The majority of certified repair centers or tire centers will be able to perform this service.

Turning rotors is a fairly simple task and costs for the service should be minimal. Be prepared to be flexible, as many shops are busy during weekend prime hours and may be apprehensive to break away from major projects for such a simple job. Also, some shops will not perform this service without seeing the vehicle and evaluating the brakes for themselves.

Another option for turning rotors is some of the major auto parts stores such as Pep Boys or O’Reilly’s. This is probably the simplest option, as they offer the service specifically for people like us.

Keep in mind that they are auto parts suppliers and will likely try to talk you into replacing the rotor instead of turning it. If you can make it past the sales pitch, the technicians will follow strict guidelines in determining if your rotors can be turned and if they can, the job will be done swift and professional.

How much does it cost to turn brake rotors?

Depending on where you go, turning rotors can be cheap to really cheap. Auto Parts stores charge pre-defined flat rates for the service which are typically set in stone. Most places will resurface a rotor anywhere from $10-$25 each. Small local shops will generally be on the cheaper end while larger chains will be more.

A repair facility may negotiate with you, especially when turning all four rotors, but will typically make sure they cover their hourly labor rate at a minimum, which could leave you paying a little more in the end. Some facilities even have the ability to turn your rotors while they are still on the car. This will generally cost you a few bucks more but it might be worth the added convenience.

It’s best to avoid dealerships which can end up charging you upwards of $50 or more per rotor. At that point, it would make more sense to simply buy new rotors every time.

Can I resurface brake rotors myself?

In general, attempting to resurface rotors yourself is a bad idea. Unless you are fortunate enough to have substantial machining equipment and a good caliper or micrometer at home, turning rotors requires fairly precise machining tools.

Some owners have been known to “scuff” new or very good condition rotors between brake jobs, but this doesn’t equate to resurfacing. Special care must be taken to ensure adequate thickness remains after turning as well as ensuring the new surface is true to the turning axis and not wavy. Any inconsistencies in the surface will greatly impact stopping feel and power.

In other words, don’t risk it!

I have those tools you mentioned. How do I turn a rotor without heading to the mechanic? 

First, take the rotors off and perform a close inspection for damage of any kind. Cracks, warping, dents, and other such flaws are all signs that the rotor is unfit for use, and should not be restored to the vehicle no matter how skillfully it is turned. 

Ignoring these flaws can lead to brake failure, either immediately or over time, and endangers the car and everyone in and around it. 

Assuming that the rotor body is sound, your next step will be to determine the base specifications of the rotor.  These are stamped in some places on the rotor body itself, although by the time a rotor needs to be turned, the markings may have become unreadable. 

Using a quality brake micrometer is exceptionally important.  These measurements determine if the rotor will retain enough material after turning to function properly.  This is so worth doing correctly no matter how many tries it takes. 

Prior to taking the measurements, ensure that your measuring tools are set in the same units of measurement as the rotor specifications.  Unit conversion can cause unwanted inaccuracies in measurement that will go on to affect the everyday function of the brakes. 

Similarly, tighten the micrometer only with the tightening mechanism included, often a slip ring or ratchet.  Tightening the barrel directly can result in an overly tight and inaccurate measurement. 

Once the measurement is taken, it can be compared to the original specifications to determine if the rotor can still be used, and how much can be removed in cutting without harming its function. If the rotor is outside of specifications or will be after cutting, replace it instead. 

Whatever your choice of lathe and lathe components, make sure that the assembly has the absolute minimum vibration possible.  Vibration during cutting makes a wildly uneven surface that requires another job to set right, or should be discarded altogether. 

Reduce vibration by using heavier flanges and mountings, or by selecting components with rubber elements that will absorb vibration rather than transmit it. 

Adjust the lathe to find a reference point by closing the facers until they just barely touch the rotor on either side.  This may be hard to see, but can be heard easily by turning the lathe to a low speed and gradually tightening the facers. 

From this point, the general standard is to remove at least two millimeters a side.  More may be required depending on what condition of rotor you are working with. 

After the cutting is done, you may want to take a second measurement to ensure that the rotor is still useable. Equally important is a visual inspection of the surface. Look for the same kind of damage mentioned earlier, and discard the rotor if any is found. 

It is worth mentioning here that the machinery needed to do this can be incredibly dangerous.  The lathe in particular is fully capable of amputating an unwary user. 

Avoid accidents by staying well clear of the rotor itself or turning it off if you feel unconfident.  Take a moment beforehand to safely secure long hair, loose clothing, jewelry, and anything else that might get caught in the cutting assembly. 

How long do rotors last before replacement is necessary?

If brake pads are changed at a regular interval, brake rotors can last over 80,000 miles. Depending on your driving style and conditions, brake pads can last 20,000 miles or longer.

If pads are changed before reaching the wear indicator, the surface remains smooth and consistent, protecting the surface of the rotor. If the brake pads are ever allowed to wear past the indicator, the surface becomes inconsistent and begins to dig into the surface of the rotor.

The reduced effectiveness of the brake pads also generates excess heat, which can warp the rotors out of shape. In this case, repair or replacement is required immediately.

Conclusion

When deciding your position on turning versus replacing, you must understand that you have more to consider than your personal safety. You have a responsibility to everyone sharing the road with you to keep your vehicle in a state that allows it to be operated safely. You may not have a family to consider, but the person in the car in front of you just might.