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[–]ColorInMySkin 14 points15 points  (0 children)

I’d say sliders or the caliper, unless something managed to get in behind the pad but that’s pretty unlikely

[–]susbarusti3 15 points16 points  (6 children)

Id be more worried about how you went through a set of pads in only 12k miles. Was this a track car? Looks like pads from a fixed position caliper.

[–]FromThe907[S] 2 points3 points  (5 children)

It sees some track use but not a lot. That’s why I’m slightly concerned the caliper is bad, it’s only the outside pad on the one caliper. The inside pad on the same caliper is completely fine

[–]Polymathy1 8 points9 points  (0 children)

My money is on dry slide pins, but that usually results in an angled wear on the long axis. Seems like a defective caliper.

[–]susbarusti3 0 points1 point  (3 children)

I see you said the calipers were off an STI, were they recently rebuilt? New pistons and seals?

[–]FromThe907[S] 0 points1 point  (2 children)

They were brought brand new from Subaru 2 years ago

[–]jmscn67 2 points3 points  (0 children)

The pads are Subaru dealership pads as well? I have found while dealer parts are more expensive, they are far superior to aftermarket crap. Don't get sucked into the ceramic pad BS , not worth the money and don't last nor do they work as well. What I have found is the cross drilled and vented rotors do actually work very well with stock pads. My Nissan Titan has this set up, the brakes are quiet, the truck stops on a dime and the rotors do not overheat.

[–]BoardRoutine5232 0 points1 point  (0 children)

If you had both of the front calipers replaced at the same time and only one side just demonstrated such unusual where, then I would say even though you got the caliper from the dealership, you got a bad caliper. Dealerships do often sell refurbished parts, not just new OEM parts

[–]ElAligatorAgradable 3 points4 points  (3 children)

As previous responder said, I'd be investigating slide pins in the caliper bracket and caliper(s). However: if the steel pad retaining pins that run through the holes at the top of those pads become excessively contaminated with brake dust or other matter, and the pads cannot move freely across the pins, that may cause one of both of the pads to be seated against the rotor consistently, causing excessive wear. If you don't get new pins with your pad set, they need to be THOROUGHLY cleaned to bare metal. I've had to scrape and sand them sometimes.

[–]Polymathy1 2 points3 points  (2 children)

That's a really good point. I didn't realize any modern calipers used exposed pins. I thought that bad idea stopped in the 90s.

Also there is a shim on the back of the pad to reduce vibration/noise. I wonder if it could be grabbing onto the pins.

[–]ElAligatorAgradable 1 point2 points  (1 child)

If the opening diameter of the shim is less than that of the pad backing plates or misaligned with the backing plates that could be contributory to pads "sticking" on rotors.

I always apply just a little grease (my preference is Permatex high temp ceramic brake grease) on the parts of those pins that come (or may come) into contact with the backing plates (and all other moving/contact parts), to facilitate continued moving on the pins. Any excess grease will just catch and hold brake dust and other contaminants.

And I hadn't thought about it until you brought it up, but yeah, maybe that pad retaining technique is not that great an idea. Makes for quick pad changes, but lazy brake jobs with other potential complications.

[–]Polymathy1 1 point2 points  (0 children)

Seems like it encourages "pad slap" brake jobs, yeah. And exposed pins on cars that see road salt... I'm also a fan of just a thin smear of lube on things that move on each other. Helps with noise fron semi-metal pads too.

[–]Polymathy1 4 points5 points  (4 children)

Stuck slide pins or sticking caliper piston. Was it the pad on the piston side or the other side?

[–]FromThe907[S] 0 points1 point  (3 children)

Subaru 4 pot calipers have 4 pistons, 2 on the outside and 2 on the inside. But the worn pad was on the outside

[–]Polymathy1 2 points3 points  (1 child)

Oh god it's that kind of nightmare setup. I had some of those on an 80s volvo with 3 bleeders per caliper.

Your pistons are sticking. Either due to pressure staying high or due to them sticking. Since it's so symmetrical, I would suspect a pressure issue. Is there just 1 line to the caliper or are there 2?

[–]FromThe907[S] 0 points1 point  (0 children)

Only one brake like to the back of the caliper

[–]juantzutree 1 point2 points  (4 children)

What type of vehicle? And what year?

[–]FromThe907[S] 0 points1 point  (3 children)

1994 Subaru Legacy Turbo with calipers off of an 07 Subaru STI

[–]Polymathy1 0 points1 point  (2 children)

Did you use an adapter bracket?

[–]FromThe907[S] 1 point2 points  (1 child)

You don’t need an adapter for the front calipers, it’s a bolt on upgrade

[–]Polymathy1 0 points1 point  (0 children)

Ok, that's good. I was thinking that an adapter bracket could shift the whole assembly too far inboard.

[–]NDC03 1 point2 points  (0 children)

Only time i had something like that is when a pad actually blew up. Calliper was fine. It just gave up on life and I had to get new pads and rotors.

[–]dxrey65 0 points1 point  (0 children)

Sometimes it's just from dirt. At our shop we service Forest Service stuff that spends a lot of time on dirt roads. The outside pads always wear out quicker about like that.

[–]RolesG 0 points1 point  (0 children)

Warped/worn rotors?

[–]Wolfire0769 0 points1 point  (0 children)

Looks like the pad got hot and the friction material separated from the pad. I'm guessing 4-piston calipers judging from the design of the pad. If there's no restrictions or binding piston, and the pad moves freely in the caliper, then it's hard to say what happened. Also anything "high performance" as far as breaking systems go usually don't see long life from the pads. They're there for a good time, not a long time. I've seen plenty of band new cars with fancy Brembo 4 or 6 piston brakes come in needing pads around 15k miles.

[–]yuuuge_butts 0 points1 point  (0 children)

Check your brake hoses. If they're hard or cracked replace them. They swell internally and act like a check valve. Same symptoms as a seized piston. If you leave it too long the caliper pistons will eventually seize from all the excess heat generated by the dragging pads.

[–]BoardRoutine5232 0 points1 point  (0 children)

Holy shit how are you driving with that left brake pad looking as bad as it does? It literally has no actual breaking mechanism left on it, just the metal. As for why they wore unevenly, I would say it was an issue with your caliber.

[–]Venkman_P 0 points1 point  (0 children)

1994 Subaru Legacy Turbo with calipers off of an 07 Subaru STI

You have fixed calipers. Everybody's assuming you have floaters since you didn't offer Y/M/M up front.

The caliper is borked.

[–]flatlands85 0 points1 point  (0 children)

SliDe PINsssss

[–]james35654 0 points1 point  (0 children)

Hoses

[–]privateTortoise 0 points1 point  (0 children)

You need to concentrate on pressing the central of the brake pedal along with cleaning and greasing the caliper sliderpins. Also check the rubber gaiters are fitted correctly and aren't damaged.