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Ledge on Driver Side Rotor

1436 Views 11 Replies 8 Participants Last post by  SomeGuy
Just wanted to get some opinions on the attached photo. Basically there is a fairly deep ledge on my driver side rotor. I have not encountered this issue before but I assume it would indicate a malfunctioning caliper piston causing only the upper brake pad to engage. I will be dropping it off at the dealer for an unrelated warranty repair and will make note of this while I'm there. Anyone have any differing opioniosn on what might be going on with my brakes?

2017 GTS
30K Miles

245586
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Does it pull to the opposite side? Or make any noise?
Um... Where to begin?

1. There is NO upper brake pad. There is a brake pad on the inside and outside of the disk/rotor held in place by the caliper.​
2. The caliper piston location can be seen in the photo above by the circular arc by the bleeder nipple cover. That piston cannot​
push against the pad and hence the disk in a manner to yield the stepped wear depicted.​


Potential explanations for the uneven ware might include:

1. Defective material composition of the disk exhibiting this uneven wear​
2. Defective brake pad material. Perhaps part of the area of pad material composition is harder than the rest of the pad surface?​
3. Contamination of the assembly by the introduction of a stone, etc. that may have become wedged into the pad-disk gap​


This should be disassembled in order to determine what is the root cause for the uneven stepped disk wear.


Good luck!
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I've seen this before and wouldn't be concerned unless you have a braking issue. And this isn't a nuclear explosion so root cause analysis will not be required.
I've seen this before and wouldn't be concerned unless you have a braking issue. And this isn't a nuclear explosion so root cause analysis will not be required.
I'd get it looked at. It may have been there a while and is no longer there. But if something is still jammed in the pad, if it were me, and it isn't, I'd take a look.
Have you ran your finger nail across the rotor to see if that is a groove in the middle or a lip to drop off? It looks like a groove to me. I've had that happen before on a different car. It was from a stone that got caught between the pad and the rotor. The stone cut a groove into the rotor. Pad was removed to remove the stone and reinstalled. Groove was still on the rotor but braking wasn't affected as far as I could tell.
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Have you ran your finger nail across the rotor to see if that is a groove in the middle or a lip to drop off? It looks like a groove to me. I've had that happen before on a different car. It was from a stone that got caught between the pad and the rotor. The stone cut a groove into the rotor. Pad was removed to remove the stone and reinstalled. Groove was still on the rotor but braking wasn't affected as far as I could tell.
I have and it is definitely a ledge. I've had plenty of grooves in the past but never a ledge which is why this is so alarming. I will def ask my SA about it when I am at the dealership next week.
Um... Where to begin?

1. There is NO upper brake pad. There is a brake pad on the inside and outside of the disk/rotor held in place by the caliper.​
2. The caliper piston location can be seen in the photo above by the circular arc by the bleeder nipple cover. That piston cannot​
push against the pad and hence the disk in a manner to yield the stepped wear depicted.​


Potential explanations for the uneven ware might include:

1. Defective material composition of the disk exhibiting this uneven wear​
2. Defective brake pad material. Perhaps part of the area of pad material composition is harder than the rest of the pad surface?​
3. Contamination of the assembly by the introduction of a stone, etc. that may have become wedged into the pad-disk gap​


This should be disassembled in order to determine what is the root cause for the uneven stepped disk wear.


Good luck!
Yeah poor choice of wording. I just meant the upper part of the brake pad. Since there are 3 pistons (or whatever the 3 black circular objects are called) I just assume the outermost one could be applying contact independent of the two innermost pistons. Maybe the brake pad is broken and the piston is free to move independently of the other two?

I don't know but therE is definitely a ledge and not a groove. So it seems something is wrong either mechanically or in material. I can't see a possible scenario in which a stone or some debris could cause this wear pattern.
A ledge is something that sticks out but I think you said it is deep? That doesn't make sense to me. Are the brakes original? It is nice to get as many miles as possible on a set of brakes but I see many Macans getting rotors at 40k miles so the rotor is 3/4 gone. We all love brakes and the calipers especially have become a cosmetic item, but rotors are not a cosmetic item and their appearance is secondary to function. The groove is caused either by some foreign material or a hard spot on the pad. If I went to the trouble of disassembling the front brakes at 30k miles I would seriously consider replacing the rotors along with the pads. If no braking issue exists, I would just drive on them for another 10k miles. If you can get the dealer to do this for you for free, more power to you.
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So, what looks like a grove in the picture above is actually a ledge; and the lower portion of the rotor face is thicker than the upper portion of the rotor?

Not sure how that would happen, unless the bottom half of the friction pad is missing. The shop should be able to sort out the problem fairly quickly.
So, what looks like a grove in the picture above is actually a ledge; and the lower portion of the rotor face is thicker than the upper portion of the rotor?

Not sure how that would happen, unless the bottom half of the friction pad is missing. The shop should be able to sort out the problem fairly quickly.
Yes this exactly. It is 100% a ledge with a +/- mm difference in thickness on either side of the ledge. The inner portion of the rotor is the thicker of the two which is why I think the outermost piston is somehow applying uneven pressure. I just don't understand how it could be such a defined line unless the brake pad is broken allowing the outer piston to apply greater force than the inner two. Will definitely ask about it on Friday.
That's interesting...I've seen uneven wear top to bottom plenty of times before but never with a distinct step. It has nothing to do with the pistons pushing top/bottom, the multi-piston design is just to provide even pressure across the length of the pad (since the pads are long, one piston pushing in the middle would effectively "bend" the pad), not the width.

Only thing I could think of is potentially a piston that has seized/jammed at a slight angle or maybe a poorly cast rotor or poorly made pad? Seems more like a defect than a result of normal wear.
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