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2010 2011 BMW 5 Series Forum F10 F10 Technical Topics Wheels / Tires / Suspension / Brakes Question about strange brake rotor wear
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      06-01-2019, 12:37 PM   #1
Walt White Coupe
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Question about strange brake rotor wear

2013 650 ix with 30,000 miles.

Over the last 2000 miles I've noticed that the left front brake pad is not making full contact with the rotor at the outer edge. The brake pads still have a lot of life left based on current thickness and the wear on the rotors themselves is relatively minor with a very small lip at the outer circumference.

Tried some hard stops to see if that would make the pad fully contact the rotor but no change. Planning on trying some really hard stops next but wondered if anyone has seen something like this before. Thanks in advance.

Left Front Rotor:


Right Front Rotor:
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      06-03-2019, 01:54 PM   #2
wcr3d
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It's not uncommon, actually pretty typical.
Just manufacturing variations.
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      06-03-2019, 03:19 PM   #3
Walt White Coupe
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I seriously doubt that. For 28,000 miles I was getting a full sweep of brake rotor and then 2,000 miles ago the sweep area decreased by 1/4 of an inch at the outer circumference.

I went through a typical brake "bedding" procedure that included around 8 hard slowdowns from 60 mph and I started to get some contact at that outer 1/4 inch edge with the brake pad. Hopefully with little more miles and brake pad wear, I'll get full contact on the rotor again. Still wondering why this is happening.
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      06-03-2019, 04:13 PM   #4
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Just a thought, based on the way I've seen brake systems degrade over time in the salt belt....

Consider whether the backplate of your pads could be compromised. It could be delaminating, corroding, and/or flexing when the brakes are applied. The outside edges look like there lots of pad left, but it's still wearing in the middle closer to the piston where you can't see directly. It'll also start affecting the contact patch oddly.

If you've got a year-round car from 2013 in PA with original brakes, this could be happening... If it's summer-only, way less likely.
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      06-04-2019, 01:03 PM   #5
wcr3d
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You skipped the part about it wasn't there before.
Makes a difference.
That small lip you mentioned, you chipped the edge of the pad.
You can bed all you want, it will remain with uneven wear.
BTW, bedding is just excessive wear unless you are on the track.
You can turn the rotors but that pad will still be uneven.
You would need to even them both to get it back.
Unless it really bothers you there is really no harm.
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      06-04-2019, 01:18 PM   #6
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That small lip you mentioned, you chipped the edge off the pad.

That's what I thought was a possibility also.

But when I did that hard braking, I was getting contact on that outer 1/4 inch of rotor. Not enough to clean it off completely but there was contact. If the pad was chipped, that contact would not have happened.

And while I'd like to know what's going on, not enough to take it apart, yet.

I guess it's possible that a small piece of brake pad, like a flake, could have been chipped off the brake pad and that's why I'm getting some contact on hard braking. If that's so I'd expect it to return to "normal" after the rest of brake pad wears down some more.

Last edited by Walt White Coupe; 06-04-2019 at 01:30 PM..
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      06-04-2019, 04:31 PM   #7
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2000 miles ago you got a chip in the pad.
During those 2000 miles the pads and rotors have worn down, pads wear typically at twice the speed of rotors.
Yes now it's finally touching, but it will not catch up.
That lip in the rotor will begin to wear but the pads will wear faster and that step in them will stay, being worn by the lip in the rotor.
The ONLY ways to fix are new pads and new rotor or have that one surfaced.
Without new pads also it will come back.
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      06-05-2019, 07:06 PM   #8
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So I've only put around 100 miles and very light braking but I'm seeing contact on that outer 1/4 inch of rotor. Looks to me, like I said before, that with a few more miles it's going to correct itself. Still not sure what is going on.

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