I went to pep boys because i heard squealing and my pads were worn down. he also told me that i needed to replace my rotors so not knowing anything i did but i asked them tog ive them to me so i could make sure they were not screwing me over and they did. i had 2 mechanics look at them and they said they did not need to be replaced yet. can you guys look at them and tell me if i have been taken?enter image description here

  • In case you've never seen one before, a micrometer is just a measuring tool with two adjustable fingers. It tells you exactly how far apart those finger tips are. There's nothing wrong with asking "exactly what was the reading on the micrometer?" From the answers and comments, it seems like you've replaced some rotors a bit ahead of schedule (but not crazy early). Your brakes should feel great, too!
    – Bob Cross
    Dec 10 '15 at 20:20
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    "...only 3 years old" doesn't tell us much. Is that 3 years of 70k miles/year for a travelling salesman? Or 3 years of 10-12k miles/year for an average (American) Joe or Mary? It really matters. Dec 11 '15 at 0:07
  • And even mileage isn't necessarily useful. Actual braking frequency will be more important. In a lot of freeway commuting, I see brake lights coming on in many other cars much more frequently than needed. Following too closely, for example, can lead to extra braking, especially in heavy traffic. Dec 11 '15 at 10:25

The only way to know if a rotor needs to be replaced is measuring it with a micrometer and comparing that to the manufacturers specifications, so, no, we can't tell you if it needed to be replaced.

However, since this was your first brake job I seriously doubt they needed to be replaced. Common practices is to "turn" rotors when doing a brake job. The turning process is putting it into a special machine that cuts off the surface layer of the disk, creating a smooth surface again. This normally removes only a very small amount of material and rotors can usually be turned several times.

If you let the brakes go so far that the metal backing of the brake pads made huge grooves in the rotor, they may not be turntable, but other mechanics said they were ok, so that's not the case. Also, if the rotors were warped (steering wheel shaking while braking, so you would know if they were warped), then sometimes they can't be turned and will have to be replaced. Well, you can turn them, but they can quickly re-warp.

So, in summary, I'd ask the service manager why they needed to be replaced, because with the limited information available, I don't see a need (and more importantly, neither did the other mechanics that you asked in person -- I'd trust them over me, but this "technical" explanation is probably helpful as well).

  • Great add about how the machining process works. Dec 10 '15 at 14:45
  • To @Paulster2's point... I have also replaced rotors out of laziness when doing the job myself (so I didn't have to drive to a shop), but if I was already at the shop, I would really expect them to just be turned. It really does make the rotor like new again in most cases.
    – JPhi1618
    Dec 10 '15 at 14:51
  • Thank you all for your comments! he said they used that tool you mentioned and said that the roters were in the orange and if he shaved them they would be in the red, but i am finding that hard to believe seeing they have never been turned before. am i wrong? Dec 10 '15 at 15:46
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    I have to disagree. Modern cars have pretty thin rotors and aggressive brake pads from the factory. It's really not all that often anymore that a rotor is reusable. If you specifically ran soft pads, you might get a second set of pads of use out of that rotor. With OEM pads, one and done is typical. Dec 10 '15 at 17:45
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    In the UK at least people stopped "turning rotors" many many years ago - personally, for the relatively small cost, I always just change pads and discs/rotors in one go.
    – Dan
    Dec 11 '15 at 9:50

You cannot tell from just looking at them (in most cases) ... you have to measure the thickness of the rotor to see if they need replaced. Also, it's hard to tell from the picture how deep the wear is on the rotor. The grooves could be 1mm deep, or 5mm deep ... it's really hard to tell. It really comes down to how thick the rotors would be after machining.

To assuage your fears a little, most times it is only just a little more expensive to replace the rotors than to have them machined. Replacement with brand new is not a bad thing most of the time. If I do them myself, I will almost always replace over machining, just because of the time it saves me from having to take it to a shop. Since you were already at the shop, that factor isn't there.

  • he claimed that if he shaved them it would make them too thin. they did use that device and they said it was in the orange and if it was in the red they would be too thin to shave. Dec 10 '15 at 15:31
  • That seems like a reasonable statement and along the lines of what I am talking about. If he did measure them, he did you right. Dec 11 '15 at 12:40

Squealing can be caused by a pattern of grooves in the rotor that make it look like an old vinyl record. The thickness of the rotor makes no difference on squealing, so even if there was plenty of meat left on the rotor it still needed servicing. Depending on how thick the rotors were you might have been able to machine them instead of replacing them - but sometimes the cost is the same so you might as well stick with new.

Mechanics dread customer complaints about squealing brakes and many professionals will do the pads and rotors at the same to best eliminate the probability of squealing.

I just did my brakes and only replaced the pads and this resulted in squealing. I had to go back and replace the rotors to eliminate the squealing.

If you go back to the mechanic who said the rotors were fine and told him the problem was squealing he would likely tell you to replace them.

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    "Mechanics dread customer complaints about squealing brakes and many professionals will do the pads and rotors at the same to best eliminate the probability of squealing." Big time. I got seriously tired of taking my car to the mechanic repeatedly for squealing brakes and would have been much happier to have him go for the nuclear option much earlier than he did. Dec 11 '15 at 0:13

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