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Discussion Starter · #1 ·
Hi all,
I saw a few threads on here regarding grooves in the rear rotors on 2018-19 Equinoxes. We have a 2018 Equinox with 22k miles and just noticed that we have grooves in both rear rotors. They are circular rings pretty much going around the diameter of the rear rotors. Has anyone been able to figure out what causes this? The bumper to bumper warranty just expired at the end of July. Do you think we would have any luck with getting a dealer to cover this? The brakes feel fine, but is this something that should be addressed ASAP?

Thanks.
 

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Brake pads and rotors are wearable items, I guess you won't get any help from the dealership or GM.
 

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In NY, it could fail the annual safety inspection, depending on how deep the grooves are, and how the inspector is feeling that day.
 

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I have a single groove about midway across on at least two of my rotors. Does not appear to affect function and isn't causing any noises so I'm just rolling with it.
 

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Discussion Starter · #6 ·
I have a single groove about midway across on at least two of my rotors. Does not appear to affect function and isn't causing any noises so I'm just rolling with it.
The grooves are pretty deep, that's the only reason I'm a bit concerned. No noises or other issues here either.
 

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The grooves are pretty deep, that's the only reason I'm a bit concerned. No noises or other issues here either.
If it's still in warranty I would ask the dealer.
 

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Discussion Starter · #8 ·
If it's still in warranty I would ask the dealer.
The warranty just expired about a month ago, but I know this couldn't have happened over night, so couldn't hurt to ask anyway. We've only put about 6k miles on the vehicle since we bought it with 16k, so I'm honestly wondering if it was like this when we bought it.
 

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A lot of todays brake pads have a groove in the center of the pad to allow dust to exit and for cooling. Stones can get lodged in there and put a groove in the rotor. I have one rotor on mine with a groove. It's a non issue, yes annoying to see but it's not a safety or performance issue.
Brakes live a harsh live and live in a harsh environment.
 
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@repairman54 :

But doesn't that pad groove in the center end up perpendicular to the direction of travel of the disc? I'm pretty sure it always has on the pads I've purchased.

From thread: Rear Brake and Rotor Replacement for 2018 Terrain

Has this phenomena been explained? It seems to defy logic ... unless these pads have a notch in the center running lengthwise (in-line with direction of travel of the disc)? Never seen that before!

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If a stone gets trapped it will wear and eventually come out. Only stuck in one spot is my theory so it makes the one groove in the rotor. How they get in is the mystery but the way things can fly around it's totally possible.
I had a bolt get kicked up from the road on my Harley and wedge in-between the frame and the transmission. That bolt wedged in tight and defeated the rubber mounts on the motor. I thought the crank spun in my motor it shook so bad, had to do a immediate pull over on a interstate. These are AC pads pictured.
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@repairman54 :

But doesn't that pad groove in the center end up perpendicular to the direction of travel of the disc? I'm pretty sure it always has on the pads I've purchased.

From thread: Rear Brake and Rotor Replacement for 2018 Terrain

Has this phenomena been explained? It seems to defy logic ... unless these pads have a notch in the center running lengthwise (in-line with direction of travel of the disc)? Never seen that before!

View attachment 17936
That is a picture of my rotor. They are not grooved but are RAISED concentric rings on the surface of the rotor. The grooves are cut into the surface of the brake pads. Had the dealer look at it and they said the brakes were functioning fine. No explanation for this phenomena.
 

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They are not grooved but are RAISED concentric rings on the surface of the rotor. The grooves are cut into the surface of the brake pads.
In your original post you said the grooves are in the rotors.
A lot of pads have grooves cut into them when new.
Do the rotors only have one raised ring at the otter edge.
 

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@blocker44 : yeah, I know the rings are raised. The question is - did the discs come that way from the factory, or did all that material disappear from the disc from normal use? If the material is missing, that’s pretty incredible, and I would think the discs are too thin to continue using! And where did all that material go?

If the raised ring came from the factory like that then that would seem to imply only certain type pads could be used with them?

Either scenario is completely foreign to me and I’d be inclined to get rid of those discs, but what do I know ...?
 

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In your original post you said the grooves are in the rotors.
A lot of pads have grooves cut into them when new.
Do the rotors only have one raised ring at the otter edge.
I was not the original poster. I only chimed in because Colt Hero posted my picture.
 

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@blocker44 : yeah, I know the rings are raised. The question is - did the discs come that way from the factory, or did all that material disappear from the disc from normal use? If the material is missing, that’s pretty incredible, and I would think the discs are too thin to continue using! And where did all that material go?

If the raised ring came from the factory like that then that would seem to imply only certain type pads could be used with them?

Either scenario is completely foreign to me and I’d be inclined to get rid of those discs, but what do I know ...?
The rotors were smooth when I bought it new. The raised rings are maybe 1 mm in height and could be surface rust that has built up over the last three years. The picture seems to make it look very bad, But i still have a lot of material on the rear rotors and the brake pads
 

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@blocker44 : if you say so. What about all the pitting on the disc surface ... or is that the picture, too?
 
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