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I have a Civic with a little over 20K miles with the original brake pads and rotors. One of the rear rotors has "step-like" grooves on the top and bottom. I visually inspected but can't confirm if there is any brake pad material. The strange part is that all of the other rotors have even wear and are shiny with good brake pads. When driving/stopping, I do not hear any unusual sounds like grinding and squealing and there is no vibration. I went through some of my older pictures and it looks like similar marks were on the rotor a year ago (though, unclear if they were less severe).

I confirmed that the caliper is operational and stops the rotor from spinning when the brake pedal is pressed.

I am including pictures for reference. What could have caused this type of damage?

front view of rotor

grooves in rotorbrake pad closeup

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4 Answers 4

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The 2 “step-like” grooves that you describe are all that is remaining of the operational part of the brake rotors. The rest of the surface is covered in rust and is not being used at all for braking.

A small area of rust may have initially developed on the rotor which will have acted as an abrasive against the brake pad. A matching groove will have formed in the brake pad so that the pad is no longer pressing against the rotor in that location.

With an area of the rotor no longer being scrubbed by the pad, rust will slowly spread out sideways, wearing more of a groove in the pad. This continues until you all you have left of the rotor is as in your photo.

You need to replace the rotors and pads on both sides of the axle to ensure even braking. Never reuse old pads on new rotors, even if the pads have plenty of thickness, since any slight grooves in the pads will immediately allow rust to form on the new rotors.

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  • Could a bad caliper cause this type of wear pattern?
    – jpQuick
    Commented May 24, 2023 at 22:54
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    Not necessarily, the calliper could be fine. The movement of the calliper piston and slider mechanism should be checked when servicing the brakes. As paulster has pointed out, the pad is well worn down and needs replacing soon.
    – HandyHowie
    Commented May 25, 2023 at 7:11
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It looks as though to me you've worn down through the friction material and into the rivets which hold the friction material to the pad. There are a lot of pads which don't use rivets for this and instead use adhesive. Considering the wear spots and the amount of friction material left on the pads, this seems like the most likely scenario.

As HandyHowie has stated, you need new pads and rotors at a minimum. I don't think those rotors will clean up with resurface operation, but you could have them checked to see if they'll pass muster.

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That is an unusual wear pattern. I think it is either a damaged pad or a bad caliper.

Either way: It is time for a full brake job.

  • Inspect the guide pins for unusual wear.
  • Clean the caliper slides. Does it stick? It it unusual loose or wobbly?
  • Replace pads. Is the brake material intact? How it the wear on the other pad?
  • What I am unsure: Is replacing the rotors necessary? How is the wear pattern on the back?
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It looks like you have a millimeter or two of pad material remaining; see picture below.

You really should have unbolted the caliper and removed pads from the bad side and good side of your car for visual inspection. There could be a pad material failure, piston seizing, or stuck guide pin.

Your OEM pads could have a manufacturing defect where they weren't flat so the center developed rust while the outside edges made contact.

enter image description here

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