Replacing Rotors

My Subaru dealer told me it’s routine procedure to change the rotors each time the brake pads are changed. My friend, who does his own maintenance, says the rotors almost never need to be replaced, especially if the pads are changed on time.
Who is right?

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George Mandel

Neither. The rotors need to be replaced more often than “almost never,” but generally not every time unless you’re really hard on the brakes.

I think the truth is somewhere in between.

I don’t agree that new rotors are necessary with every pad replacement, but I also don’t agree that rotors are “almost never” needed.

Here’s the thing; modern brake rotors don’t have much extra “meat,” and they usually can’t be turned without making them too thin. Once they’re at or near their minimum thickness they are subject to rapid warping.

You don’t want that.

The dealer likes to replace everything because 1); it’s more profitable, and 2); if everything is new the customer will be happy. No warped rotors. There is some logic to that.

I have an independent mechanic who is willing to replace the pads only, as long as the rotors are still OK.

If the rotors are bad, however, my mechanic will replace them, and I will pay him, without complaint, to do so. I no longer believe in turning, or resurfacing, rotors, for the reason explained above. If they’re worn enough to need resurfacing, replace them.

You didn’t tell us how old your Subaru is, or how many miles it has accumulated, so it’s hard for us to say much about your car.

My recommendation would be to take them to a shop, let them determine if they should be left alone, turned or replaced.

Shops are going to turn the rotors or replace them if they cannot be turned. Many newer cars have rotors that cannot be turned. The reason is that by doing a brake job with a refreshed rotor surface reduces returns for such things as noise, shuttering, and vibration. Basically, they don’t want to gamble.

Your friend doesn’t mind the gamble. He would probably ignore any noise or minor vibration knowing he did the job, and the brakes work just fine. I would hope that he checks the rotor thickness when he changes the pads. There is a minimum thickness to the depth of hardness on the rotors. I’ve seen rotors worked past their thickness limits, and it never ends well.

Holy cow. Do you suppose that driver was feeling any pulsation in the brake pedal?

That’s not my picture, but close to an event that I dealt with. I’m surprised he managed to make it without getting into an accident. The rotor was completely detached from the hub. Scary.

About the picture: I’ve seen them worse than that. At the shop where I used to work, we made ashtrays out of a heavy rotor (for the base), a length of exhaust tubing, and rotors ground down to the fins. People just drive with the noise, never concerning themselves about it, then push the piston out of their caliper, lose their brakes, and bring it to the shop with the story: “Oh, no! It never made any strange noises or anything!”

I just changed pads on my Camry. The rotors had even wear, braking was fine before the job and had not waited until I am metal on metal for the pads. Measured the rotor thickness and almost good as new. Only put new pads on and it is fine. Now if I had to go back and put new rotors on, no biggy, I only have myself to blame, but a shop would not want to work like that and they don’t have a lot of motivation to save money on the parts either-you are paying. But I am sure at some point the rotors would need changing.

A proper brake job means servicing the rotors and that means surfacing or replacing them.

A DIYer can skip a step like that. If a problem occurs immediately after the brake job or a month or so later the DIYer has no one to blame but themselves for cutting corners.

A shop that is expected to stand behind their brake work as to noises, vibrations, and so on has to look at this issue much differently as compared to a DIY person.
The same people at the service counter who want pads only and will gladly agree to not be upset if a problem develops WILL be upset if those new pads are squealing, groaning, vibrating or pulsating, etc. a few days or even 6 months later.
Amnesia, sometimes selective, will guarantee that they will not remember everything they were previously told.

Then put it in writing. “Customer acknowledges that they have requested us to only replace the pad. Customer has been advised that not replacing the rotor means we cannot guarantee the rotors are not warped, and therefore cannot guarantee that the brakes won’t vibrate.”

I don’t see the need to replace parts that aren’t broken just because they MIGHT warp some time in the future. Do mechanics do that with the rest of the car? “Sure, I’ll change yer oil, but uh. Hey, you might blow your engine after the oil change, and then you’ll be pissed at me for not catching that, so we’re gonna do your head gasket too.” No, they don’t, just as they don’t replace the shocks every time you buy tires.

I know it’s an industry practice, but that doesn’t mean it isn’t a waste both of materials and the customer’s money. Assuming the driver isn’t pretending to be in NASCAR and assuming there’s nothing else wrong with the brakes, rotors should last through at least 2 sets of pads without having to be turned or replaced.

Okay, lets just look at the physics of this. If the pads and the rotor are wearing evenly, then you take the older pads off and put newer ones on, the only difference is that the newer pads are thicker. So if the rotor was fine with the older pads, they would be fine with the new ones. This is again assuming wear is even and the rotors are thick enough.
I have had more issues with resurfaced rotors than just leaving them as is. So I either leave them or buy a new pair.

It’s possible to have brake noises and vibrations that were not previously there after a pad replacment. It can and does happen. Over the years it’s happened a few times when doing this on my own cars.

A properly resurfaced brake rotor should work just as well as a brand new rotor with the operative word there being properly.

Signing a disclaimer doesn’t mean much. Believe me, I’ve seen this done more than a few times.
Many customers claim they don’t remember signing that disclaimer, many have “lost” or “forgot to bring” their copies of the repair order (apparently forgetting a shop has them on file), others even claim their signatures have been forged on the disclaimers, etc.
Many will never return with a problem. What they WILL do is go to another shop and tell them just how badly they were hosed by the shop that did the brakes; conveniently “forgetting” to tell them they wanted a halfway job from the get-go.

This occurs with many things other than brakes. In one case the mechanic who worked next to me (good friend besides being a co-worker) was actually physically assaulted in the shop by a thug and his 2 buddies over this very thing. It involved a salvage yard transmission for which the thug had signed a disclaimer stating that he would not hold the mechanic responsible if the transmission was no good. Six months or whatever later the transmission failed and the thugs went to get even.

The only thing that saved my buddy (they sucker punched him from behind) was the fact that unbeknownst to the thugs I was just inside a walk through door when this incident flared up. I grabbed a 36" breakover bar and went running to assist. When the thugs saw me coming with a weapon they took off to a waiting getaway truck they had outside.

The thug got his a few weeks later after a hit and run accident. A state trooper found the abandoned car (the transmission had been replaced again by this time) and paid a visit to the thug’s house. The punk refused to be placed under arrest, made a grab for the trooper’s gun when the trooper backed up and pulled a weapon, and the punk got an accidental round right through the midsection. DOA at the hospital.

In another case, we actually got sued by a guy over an existing problem and a signed disclaimer. The service manager and myself (as shop foreman) both had to spend an entire afternoon waiting our turn in front of the judge. (We won, but still…)
So much for signed disclaimers. :slight_smile:

I understand where you’re coming from, but I don’t think that performing unnecessary parts replacements is the solution. You could just as easily be sued if something wears out on the car shortly after you do an oil change. That’s not uncommon either. “Hey, you changed my oil and now my air conditioner doesn’t work anymore. You must have broken it.” The logical extension to your premise is that you must replace the entire car with known good parts in order to properly insulate yourself from frivolous lawsuits every time you do any work on it at all.

I’m not advocating replacing or servicing anything except what is directly related to performing the job at hand as best as possible and to eliminate all possibilities of problems.

If the brake pads on your car were worn to the minimum (no noises or vibrations present) and you had a shop do the pads only followed by the brakes vibrating or making noise a day or a week later are you going to:
A. Insist the shop redo them for free because you feel they screwed up.
B. Happily pay again; only this time even more because rotor service is involved.
C. Go to another shop.

If a customer has an engine with low oil pressure due to worn crankshaft bearings what would be the proper repair?
A. Replace bearings only, ignore any egg, taper, or iffy wear limits on the crank, and hope.
B. Install a crank kit with a reground crank.

The same scenario could apply to a leaking extension housing seal on a RWD auto transmission.
A. Replace the seal and ignore the worn tailshaft bushing.
B. Replace the seal and the bushing.

There’s countless more but there’s a right way and a half way to every repair.

The crank kit example is off base. You’re talking about tearing into the motor. Expensive. Same with the transmission example. That’s the same reason I advocate replacing the water pump when you do the T-belt. For the brakes, you’re talking about taking a wheel off and removing a couple of bolts.

To answer your question, if I bring the car in and it’s not vibrating, and I only have them do the pads, and the odometer hasn’t gone up by 100 miles indicating some jerk was joyriding around in my car, I’m going to choose B, unless you try to replace the pads AGAIN, in which case the choice is C. The choice is also C if you try to force me to replace rotors that don’t have anything wrong with them. (Actually for myself, the choice is D, do it myself, because it’s easy and I don’t have to fight mechanics who want to replace crap that doesn’t need to be replaced).

Just out of curiosity has anyone seen a perfect rotor when pads need to be replaced?. All the ones I did I had resurfaced at least due to ridges etc. Your experience?

Gotta jump in here. I do all my own maintenance and have not always changed rotors when changing pads on my own vehicles; however I realize I’m responsible for my do overs if they squeal, or warp in the future. If I was working in a shop again, I would certainly try to sell the customer new rotors so he will be happy with the brake job for months or years to come. But let’s look at it from a customer perspective, if he doesn’t have the extra 100-200 bucks to spend on rotors, and they are not currently warped, I think a good discussion about the pros and cons of not replacing rotors is in order, then let him drive off not feeling like he was taken to the cleaners. (Hint: For those of you not on a budget, the economy is not doing so well lately)

Let me ask this shadowfax, and please understand that I’m not making these points to be combative about it.

Have you worked for hire as a mechanic or any position such as a service writer or service manager and had to deal with this kind of thing?

If not, maybe the difference of opinion is because you’ve never had to go face to face with someone over issues like this. Granted, it would be great if those disagreements at the service counter did not occur but the fact is that they do.
Some people who want a partial job will be perfectly fine with having to go back in and redo something they had passed on previously and have no objection to paing the tab. The majority will not he happy though and this is why many shops will flat refuse to cut a corner; they can see the potential problem looming like a runaway train.

It’s a fairly lengthy story I won’t get into but the service manager called me up once to talk to a guy about a blown engine on his girlfriend’s Subaru. The cordial boyfriend chose to ignore the disclaimer on a prior repair order and after 5 minutes of increasinly volatile back and forth he poked a finger in my face and threatened me with an axx whipping right at the service counter. Bad move on his part. I flipped the lid on the counter up and started after him but the serv. manager grabbed my arm and urged me to calm down while this guy was running for the door. At least we were rid of this one permanently.

As to defective new rotors, I’ve never seen one no matter who manufactured or retailed the part.
However, given the current climate of cheap Chinese junk being peddled it would not surprise me if some lousy one are out there.

OK, I think there is a big difference between the way a DIY’er does this vs a shop. When I am doing the work myself, I can decide whether I want to pay for new rotors upfront, or not. But then I am not going to fight with myself over lost time and having to redo the work.

I agree that as a shop you are dealing with a very broad range of personalities with different tolerances. Only if you have gotten to know your costumer you can make exceptions. I am not sure if signing papers change much.

I move a lot, have been able to know 2-3 shop owners in different states that have worked with me providing parts. One actually would let me use his shop to do my own work. While I was there I would lend him a hand with other cars, kind of became family. I am sure he was well aware that if a part I provided, failed, I was not going to gang up on him. We remained on very good terms all along.