Gouged up Rotors

[Steve C]

I replaced all four rotors,pads, and three calipers last year ~18-20K miles ago. About a month ago I heard a scraping noise from the rear and brought it to my mechanic. I didn’t have time to investigate much myself due to working on an Audi. He said the rear caliper was frozen and the brake pad was destroyed.

He fixed the guide pins and replaced the brake pads. I was looking more thoroughly at my rotors and noticed they have a gouge line on the outside of them. So, again I ordered four new rotors to replace them and when I took the front passenger side one off the inner brake pad was worn to pretty much nothing, while the outer had a good amount left. The rotor also had large chunks missing on the inside. I didn’t check the other rotors yet, since I am awaiting my brake pads, but any idea what can cause this?

The front caliper also slid freely and didn’t look seized from what I could see.

Topic

[Andrew Phillips]

[quote=”coffeysm” post=137030]I replaced all four rotors,pads, and three calipers last year ~18-20K miles ago. [/quote]
Year/make/model/engine/trans?

I was looking more thoroughly at my rotors and noticed they have a gouge line on the outside of them.

Gouging usually happens when foreign material (like sand or rust) gets between the rotor and pad, or a severely worn pad where the metal backing or rivets make contact with the rotor surface. Inferior quality pads can have imperfections/impurities that can gouge the rotor also.

So, again I ordered four new rotors to replace them and when I took the front passenger side one off the inner brake pad was worn to pretty much nothing, while the outer had a good amount left.

Pads should wear evenly. If the inner pad is wearing faster than the outer pad it means the caliper piston is hanging up in the bore and not retracting properly. When the outer pad has more wear than the inner pad it usually indicates the caliper is hanging up on the guide pins.

The rotor also had large chunks missing on the inside.

Chunks? on the surface that contacts the pad? Are these chunks like pits or broken off metal? Have a picture? Of course a bad contact surface can cause excessive pad wear also. Missing metal is usually either from mechanical damage or inferior quality rotors.

The front caliper also slid freely and didn’t look seized from what I could see.

“Seizing” refers to the action of the piston in the bore, not the caliper on the guide pins.

[Steve C]

1. It’s an 06 G35 Coupe 5AT
2. It was several fine lines digging into the outer side of the rotor.
3. The pad was down almost to the metal and the wheel spins freely without any resistance. When I replace the pads/rotors I’ll try spinning it again and press the brakes a few times to see if it’s seizing.
4. I would say it’s a combination of pits and missing metal. I could run my finger and feel an indentation. I used basic Centric rotors and ceramic pads.

[Andrew Phillips]

What you’re describing isn’t all that uncommon. Pitted rotors are a result of inferior metal casting practices. When molten metal is poured into a casting, it must be done at a certain rate. If it’s poured too quickly, air bubbles form in the molten metal and leave voids in the piece. When this happens with brake rotors, as the rotor surfaces wear, these voids begin to be exposed and results in what you discovered.

I have a friend who put Centric Premium rotors on his 97 Jetta and he noticed that they rusted quickly. When he went to change his pads he saw pitting on the back side, the front side looked fine. Needless to say he replaced them.

I would suggest replacing with OEM (Brembo) rotors and semi-metallic pads. There really isn’t a good reason to spend the extra money on ceramic pads, and they can cause excess wear on the rotors.

[Author]

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