Usually I look forward to wrenching...

"Nick Has an Exocet" (nickallain) 01/03/2019 at 22:05 • Filed to: None

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...but I’m not so sure about this one. Rain revealed that the driver rear brake on the Miata is wearing insanely unevenly. Anyone have any ideas where to start? I need to check the other side of this rotor , but it’s dark out.

The Crazy Kanuck; RIP Oppositelock > Nick Has an Exocet 01/03/2019 at 22:14

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At that point just get new pads & rotors. 

NKato > Nick Has an Exocet 01/03/2019 at 22:16

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Jack, lug wrench, wrench kit.

Pull the tire, flashlight, check wear pattern on inside. And make plans to visit your regular brake shop. 

Cash Rewards > Nick Has an Exocet 01/03/2019 at 22:25

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That was the scenario when I bought mine. Tried to do pads and rotors, turned out that the caliper was siezed. Replaced both rear calipers. Not too bad. Definitely doable yourself. It was the second time wrenching for me.

ITA97, now with more Jag @ opposite-lock.com > Nick Has an Exocet 01/03/2019 at 22:27

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Unbolt the caliper and inspect the slide pins for wear . Make sure they’re lubed and there isn't damage  or obvious wear patterns on the pins.  Then do the same on the other side...

Spamfeller Loves Nazi Clicks > Nick Has an Exocet 01/03/2019 at 22:30

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Eh, looks more like the rotor’s fucked and you’ve possibly got a sticky slider. I wouldn’t even try turning that rotor, I’d just scrap it.

MM54 > Nick Has an Exocet 01/03/2019 at 22:40

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Neat.

Something’s stuck, whether the piston or slide pins/sliders or both. You could probably get away with taking it apart, cleaning everything, and re-greasing on assembly, but it may be a good excuse/opportunity for new pads and rotors along with the aforementioned cleanup/greasing. Nothing major to do, mechanically.

merged-5876237249235911857-hrw8uc > Nick Has an Exocet 01/03/2019 at 22:44

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Second for check the pins for movement and make sure the caliper moves and the piston isn’t froze up.  After that new pads and rotors.  

MiniGTI - now with XJ6 > Nick Has an Exocet 01/03/2019 at 23:05

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Back brakes on my GTI Look a little like that. Wear is smoother on the outside edge, kinda cloudy and uneven closer in. Both sides about the same. 80k on the factory pads though and fronts look fine.  P lanning to do all 4 when weather warms.

facw > Spamfeller Loves Nazi Clicks 01/03/2019 at 23:15

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What make you suspect the rotor? Do you think the non-rusty sections are raised? I mean if you are going to take everything apart anyways to see if the caliper is fucked, it’s probably not a terrible idea to replace the pads and rotors, but I’m curious as to your thinking?

Spamfeller Loves Nazi Clicks > facw 01/03/2019 at 23:32

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Looks exactly like a classic bad cut job, where the apprentice walked away and left it spinning while he went to the bathroom or whatever. Pad’s making contact in two places, rusty section between them got cut too low. Should never look like that.

Even if it’s not a bad cut, means something in the pad cut the rotor that bad, same verdict. Rotor’s scrapped, pads scrapped. Something did that cut , and it definitively wasn’t the caliper.

Caliper is, in all likelihood, just fine. Bad caliper is not going to give you two perfectly spaced grooves like that. No way, no how. Only way you get that is a bad rotor or bad pads which have trashed the rotor. It’s possible the caliper’s seized braking but I don’t see any heat damage, certainly not enough to warp the pad backing, so it’s gotta be FOD (Foreign Object Debris) or bad cut.

With no indications of FOD such as cracks, cuts, gouges? Bad cut or defective pad.

Now, as to the sticky slider? Experienced eye. See the pad clip there at the bottom? It’s got some rust on it, and it’s got gunk on it. Tells me from that image alone that it got run dry and scraped up. Well, run dry and scraped up, it’s gonna stick and bind. But there, it’s just the pad clip, and a dab of lube fixes it right up.

facw > Spamfeller Loves Nazi Clicks 01/03/2019 at 23:46

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Thanks for the explanation !

wafflesnfalafel > Nick Has an Exocet 01/03/2019 at 23:59

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ok, that’s weird.  (cracked pad?)    Related, I’m a proponent of replacing rotors when doing brakes anyways, relatively cheap and you don’t have to worry about warping, etc.

Nick Has an Exocet > Spamfeller Loves Nazi Clicks 01/04/2019 at 00:01

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Thanks for the detailed look. I ordered some pads and rotors already. The calipers are under 1 year old. I assume I should do both sides to keep wear even, yes?

Nick Has an Exocet > ITA97, now with more Jag @ opposite-lock.com 01/04/2019 at 00:02

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Will do!

Nick Has an Exocet > MM54 01/04/2019 at 00:02

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Definitely doing new pads and rotors . They’re ultra cheap. Both sides <$100. Why not.

Nick Has an Exocet > MM54 01/04/2019 at 00:02

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Definitely doing new pads and rotors . They’re ultra cheap. Both sides <$100. Why not.

Nick Has an Exocet > NKato 01/04/2019 at 00:03

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I am my brake shop!

Nick Has an Exocet > merged-5876237249235911857-hrw8uc 01/04/2019 at 00:03

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Definitely checking the piston and pins.

Nick Has an Exocet > MiniGTI - now with XJ6 01/04/2019 at 00:04

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Right on. These have under 10k on them.

Nick Has an Exocet > wafflesnfalafel 01/04/2019 at 00:04

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Agreed! Going to take it apart and find out. 

Nick Has an Exocet > wafflesnfalafel 01/04/2019 at 00:04

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Agreed! Going to take it apart and find out. 

PartyPooper2012 > Nick Has an Exocet 01/04/2019 at 07:32

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I would start with checking the rotor for warping .

I don’t know how old this pad is, but if it’s new, possibly old pad wore out the rotor uneven.

Might be as simple as having the rotor resurfaced.

It could be caliper compressing pad at edges but the pad backing is fairly thick and I would doubt it would bend that much.

It could also be some crap stuck in the pad and that is acting as the pad, not pad itself.

It could also be a damaged pad where there is nothing left in the middle section, but that would crumble apart fairly quickly at that point and would leave you with caliper pistons rubbing on the rotor and they are usually inline so you would only see one line. 

Long_Voyager, Now With More Caravanny Goodness > Nick Has an Exocet 01/04/2019 at 07:40

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Rotors/Pads/Calipers. Chances are your caliper is stuck, causing the odd wear. You may be able to get it freed and regrease it, but they never last long after doing that, so I’d say just do it all.

Spamfeller Loves Nazi Clicks > Nick Has an Exocet 01/04/2019 at 10:40

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Yep! I’d also make sure you carefully inspect the pads and caliper while you’re in there, and make sure you lubricate the sliders well. The outside pad has no piston acting on it with designs like these. But really just looks like a bad pad or rotor.