How to tell rotors are good or bad?

How to tell rotors on car are bad or good posted a picture below of one of my rotors only answer if you know stuff about cars..

Update:

Just curious if it is a good rotor or not 

Update 2:

Really all I am asking now is based on the one picture I gave from what you can see does it look clean and what a rotor should look like with normal use

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18 Answers

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  • 4 weeks ago
    Favourite answer

    It looks near enough perfect, very slight but even wear, just like a good brake disc (rotor) should.

    You can see a slight "wear step" near the inner edge (top of the photo), but it's barely perceptible in that image.

    From that alone, I'd put them at possibly a quarter to a third through their overall lifespan - though as other say, the definitive "worn out" point is determined by measuring the thickness through the overall disc in the wearing areas.

    All makers publish that data, even if it's not a visible marking on the disc hub.

    As long as you are not experiencing problems, it's fine.

  • Phil M
    Lv 7
    3 weeks ago

    This rotor is bad.

    Attachment image
  • garry
    Lv 4
    4 weeks ago

    get a good pair of vernier calipers and measure wow thick they are , after all if they have thinned out below the service thickness then replace them .

  • Anonymous
    4 weeks ago

    Brake pads wear out before a steel rotor does. Yours is fine.  When you start to hear squealing/squeaking when you step on the brake pedal(with the radio volume down low) that is the pads telling you they need replacing.

     It will be just the pads. The mechanic will know because the look may change by the time you need pads and you ignored the SCREAMING they were making. They are almost GONE.

    It is comparable to when you had a pencil erasure on the end of your pencil and you wore off all of the erasure down to the brass and now you  are gouging out the paper to erase it.

    . You will be gouging out the steel.  It is a horrible sound, worse than fingernails scratching a blackboard (more like a shovel scraping a gravel driveway(only worse)

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  • Anonymous
    4 weeks ago

    From what I can See, fine. I have seen Backsides that were grooved,  though. Take it completely off  and Look. . Any doubt, replace. 

    Think of it This way  Would you drive your wife,  baby on those? If any doubt, fix it.

  • Fred G
    Lv 4
    4 weeks ago

    If when braking it's not pulling, vibrating, grinding, smoking, etc, and the car is stopping.. Your rotors are good.. If you crash through the back of your garage when braking your brakes and maybe rotors are bad.. 

  • CB
    Lv 7
    4 weeks ago

    Looks fine and all this advice about warped rotors is hooey - very very rarely do rotors warp  - if they surge it is USUALLY because they get a build up of brake material that can be removed (with 4 or 5 very fast stops from about 50 mph), or having them turned to clean them up. Look my claims on google - plenty of info about this issue can be found.

  • 4 weeks ago

    It doesn't look bad, but what needs checking is thickness and if it's warped. If there is no shimmy when you brake, warpage is not very likely.

  • 4 weeks ago

    I've done hundreds of brake jobs as a master mechanic. I always replace rotors with the brake pads. Even if they "look" good there is still a glazing burnt into the rotors from all the braking done with the old brake pads. The glazing keeps the heat from dispersing properly which leads to hot spots, warpage and brake fade. Buy premium brake pads that come with the metal hardware that should always be replaced. Make sure to wire brush, file or scrape the rust build up on the caliper brackets before installing the new metal hardware.

    Source(s): Mitsubishi Master Tech
  • 4 weeks ago

    Low tire pressure is a sign of a bad rotor. If you have low tire pressure, rotors will likely be bad.

  • Rick
    Lv 6
    4 weeks ago

    there should be a MINIMUM THICKNESS number cast into them somewhere.  IF they are below that thickness, they are junk ..............IT will be cast on some NON-WEARING surface .............

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