Odd pattern on removed brake rotor

[rkrenicki]

So, I have had some issues with the stock brakes on my BE, severe shake in the steering wheel above 50mph for a few minutes until it levels out, and a significant reduction in fuel economy.

I am sure that it is a sticky/dragging caliper, but when I pulled the rotor off, I saw this on the inside surface.. and I cannot figure out what it is. The brake pads do not have triangular edges, so I have no idea what would have put this pattern into the face here. This is also not an old rotor.. I replaced both fronts about this time last year.. Overall it seems to be in fairly decent shape, except for these mystery markings.

https://sl-i.net/FORUM/images/imported/2014/03/IMG_20140302_115833_zpsfs3f11oe-1.jpg

Does anyone have any ideas what this is?

[Dead91silvia]

Could be a really bad rotor casting. I've seen it on cars before...

[GTDrifter]

Its just showing you which way it was spinning lol

[Dead91silvia]

Can you post a side view?

[Matty2Hotty]

Says made in USA, pretty sure stock rotors are made here!

[rkrenicki]

These are not Subaru rotors, I bought them from Advance Auto Parts last winter. I did not notice the "Made in USA" when I installed them, but I did notice it when I saw this. I just checked the rotor from the other side and it also has these marks, but they are not nearly as pronounced as these are. The "arrows" are in the opposite direction of normal rotation, this rotor pictured was the passenger side.

What sort of side view do you want Dead? Straight from the edge? I have them in the back of my truck so they are here at work with me today.

[decke48]

what kind of pads did you have on? sometimes pads have brass and copper leaching from over heating or less quality bonding. it will leave impressons on where the pad stopped on the rotor and after time they will slowly wear to pointed lines because the copper and brass is sort of electrolytically bonded to the steel from friction. alot of the time in sliding calipers the inside pad applies more force.

[rkrenicki]

I do not recall the specific model of pad, but they were from Advance as well. I could understand leaving impressions of the pad on the rotor, but the pads do not have triangular edges which is what is baffling me. I also noticed that one of the lines points in counter-clockwise direction, and one is straight across the contact area.

I guess if the original casting mold was built in sections, these could be seams between the sections, but I would think those sections would have been larger than these, and they are quite irregular in size.

[dodik]

that is brake pad deposits, generally it shows in more vertical fuzzy lines, personally have never seen them so pronounced angular shape. without seeing the pad iam pretty sure it had at least one slot in the middle and was slightly angled at the edges not round is that correct?

Basically cheaply designed pads most likely inconsistent or not properly mixed pad material when they were manufactured. Autozone brake pads are just as bad, especially the higher priced ones. Were these 40-65 dollar pads?

[rkrenicki]

No, they were likely the middle-priced pads. Probably about $30 for the set. I have the calipers and pads here too, I will get a picture of them.

[Dead91silvia]

Yeah, straight side ways. Just curious.

[rkrenicki]

ugh.. So I am very unobservant. The edges of the pads are not straight.. they do have an angle. These marks line up with the edges of the pads. I didnt really look at them very carefully, but I thought they were squared off on the sides of the friction material.

So.. please ignore this post.. I really should have put a pad on the rotor and looked at how it sits.

[ctbrighton]

well that blows, i was really curious what it might be since it def wasnt the pads haha

[rougeben83]

lol yeah I was going to say they look like pad deposits, esp when the pads side for a while and there's moisture in the air.

Best way to get rid of them is to use the brakes more aggressively lol.

[rkrenicki]

Well, let me clarify what I mean.. the pads are straight. but when you put a mostly square pad on a round rotor.. you see the corner of the pad there as a triangle. There is the straight line there that I do not have an explanation for, but it is a moot point since I have already replaced the rotors.

[ctbrighton]

straight line would be the middle of the pad where they cut a groove in the material to allow for expansion/contraction.