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Nobody wants to feel as if they are being taken advantage of by a mechanic. Women, in particular, sometimes get the impression that they are targets for unnecessary vehicle maintenance work. We found this post by a Honda CR-V owner on a popular social media group’s page, and it is a perfect introduction to the topic of changing rotors – or not – when brake pads are ready for replacement. First, let’s look at exactly what this owner posted in a search for help:
A mechanic said that I must replace rotors while replacing brake pads without even looking at the car. This is for my 2019 CR-V. Do they really need to be changed?
A Common Brake Job Question – Pads and Rotors Both, or Just Pads?
The brake pads on all mainstream vehicles were specifically designed to be the wear item in the braking system of cars with disc brakes. They are quick and easy to swap out, assuming nothing goes sideways, and they are inexpensive compared to most car parts. The brake pad serves as the friction surface through which the calipers pinch the rotor to slow the car. As such, they must be made to wear out to preserve the rotors from being gouged by the brakes. Most vehicle owners know a brake pad when they see one, and we all can agree that they are wear items. But what about the sturdy-looking metal rotors? They look like the kind of part that should last a long time, and certainly longer than the sacrificial brake pads.
Indeed, the original idea of disc brakes was precisely what we might imagine. The pads are easy to remove and replace, making the brakes affordable and straightforward to service, perhaps even by the vehicle owner at home. However, times have changed, and the design has evolved over time, primarily due to real-world conditions that make rotors sacrificial as well.
Mixed Advice From Fellow Owners
Under the post we are using as our story premise, many folks weighed in with opinions. Some say, “Yes, replace the rotors,” and others say, ‘No, you can just replace the pads.” Here are some examples:
– “If the rotors measure thick enough to cut, then they can be cut.”
– “Measure thickness and check for warping. Replace only if it is below the service limit. Turning the disc (resurfacing) is a good practice when changing pads. Make sure to break in the pads for optimum output.”
– “Rotors have a minimum thickness measurement on the inside. Use a micrometer to measure and compare.”
These comments all have one thing in common. They are assuming that the shop in question will use a lathe. If the shop will not, then the advice really doesn’t apply. Now let’s look at a few different takes on this:
– “Rotors are so cheap now compared to years ago, it’s better to just replace than risk a bad resurface job, and you’re stuck with a shaking steering wheel every time you hit the brakes.”
– “By the time you get them machined, it doesn’t cost much more for new ones.”
Changing Designs of Brakes – Sacrificial Rotors
Over time, disc brake rotors became less and less robust. Automakers dislike heavy brakes because they increase costs, add weight, which is always undesirable, and are considered “unsprung weight,” meaning they sit below the suspension. That hurts handling. In the old days of wooden ships and iron men, the rotors were thick, made of high-quality metal, and intended to last many brake jobs. No more.
Changing Repair Shops – Lathes Going Away
With the old design, those heavy, thick rotors could be machined flat. A lathe would either be placed over the rotor or the rotor removed and put into a lathe—usually the former. The machine would strip away a bit of the surface of the rotor, which would eliminate any grooves or gouges. The result was a flat, even rotor that was like-new except for one little detail. The rotor got thinner. When the machining was done, it made the rotor thinner, and that can cause some issues. A significant side effect was the warping of the rotor due to heavy braking and the resulting heat. Manufacturers designed those old rotors to be thick enough to handle a few machinings before they were “out of spec” by being too thin. The rotors were then changed – at great expense – to new ones made by the car manufacturer or a respected aftermarket company.
Today, it’s rare to find any shop that will machine a rotor. The lathes are either gathering dust in a corner or gone altogether. The skill of machining a rotor flat, though not rocket science, is also fading from memory.
Modern Rotors – Thinner, Lighter, Disposable (Recyclable)
As automakers began making rotors more and more affordable (cheaply) and with less and less mass, they became disposable. The idea being that they would not be re-machined flat during brake jobs, but instead be recycled and replaced. What an outrage, right!? Not really. That lathe was expensive and required regular care and maintenance. Employing the lathe required some practice and time to master, including measuring the rotor’s thickness and learning to place and remove it from the lathe. Time is money. And at some point, the expensive, heavy, and thick rotor was going to need replacing anyway. So, on balance, disposable rotors that are less costly and require less skilled labor to mount became the de facto standard in the industry.
Brake Job – Do It Right The First Time, Or Roll the Dice To Save a Few Bucks
If you look online, you’ll find many well-intentioned do-it-yourself shade tree mechanics who claim, “You can replace those pads yourself and then you’re good to go.” They are not really wrong. Assuming you are not an 81-year-old grandmother with a bad hip and fading vision. Let’s face it, vehicle maintenance is not for everyone. Most owners of mainstream vehicles let their dealer or a local shop replace their brakes. They are not up under the car on nights or weekends after they get back from their day jobs, hoping the brake job goes well so they can drive to work the next morning.
If a mechanic or a homeowner replaced just the brake pads, it might work out OK. Or, the brakes might squeal or squeak. And then the whole thing needs to be done over again. The brakes may also pulse due to rotor warp. Or the brake pads, now installed over grooved rotors, may wear more rapidly and need replacing in a short time. All of these scenarios mean lost revenue for shops. So, almost no respectable mechanic will change just your brake pads. It’s not a wise choice for them. Unhappy customers who come back with a problem are not profitable.
Hybrids and EVs Have Longer-Lasting Brakes and Rotors
There is some good news on the brake front. An increasing number of new vehicles now feature standard electrification in the form of a battery-electric or hybrid-electric powertrain. These all share an essential commonality – regenerative braking. The electric motors can slow the car and put back some of that energy into your battery, saving you a lot on gas. They also help prevent your brake pads and rotors from wearing out. As we detailed in our story, Hidden Benefit – Toyota Prius Owners Find Their Brakes Last Over 100,000 Miles, many Toyota hybrid owners find that their brakes last two to three times longer than those of their prior gas-only cars. This is a well-known plus of electrification.
Summary – Replace Your Rotors When You Have Brakes Serviced
The upshot of this story is that it is not a scam when a mechanic tells you that you will need rotors when you replace your brake pads, and he does not even have to look at the car to know this is true. You won’t pay more than you would have if the car were equipped with long-life rotors, as they would require machining and eventually become too thin to be reused.
Do you agree with our conclusion? Tell us your thoughts in the comments section below.
John Goreham is the Vice President of the New England Motor Press Association and an expert vehicle tester. John completed an engineering program with a focus on electric vehicles, followed by two decades of work in high-tech, biopharma, and the automotive supply chain before becoming a news contributor. He is a member of the Society of Automotive Engineers (SAE int). In addition to his fourteen years of work at Torque News, John has published thousands of articles and reviews at American news outlets. He is known for offering unfiltered opinions on vehicle topics. You can connect with John on LinkedIn and follow his work on his personal X channel or on our X channel. Please note that stories carrying John’s by-line are never AI-generated, but he does employ grammar and punctuation software when proofreading and he also uses image generation tools.
Top of page image taken by John Goreham.
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