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Brake rotor rust - indicative of caliper issue? #5432714 05/18/20 06:55 PM
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fsdork Offline OP
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Attached is a photo of one of the rear rotors on my '03 Explorer. All four rotors look similar, although the rust is a bit more scaly on the rear. All four corners need new pads, and based on the amount of rust on the rotors, I plan to replace them as well.

What I'm looking for input on is the ring of rust around the outer edge of the pad contact surface on the face of the rotors. I realize a small lip of rust in that area is normal, but this seems to be a bit much, and definitely overlaps the pads in that area, so it seems there should be pad contact there by design. Is this caused by the caliper pins not functioning correctly? If so, it is likely that servicing the pins when I do the rest of the work will cause the calipers to function properly again?

I'm trying to put together a Rock Auto order, and would like to order the calipers along with everything else if it is reasonably certain I will need them. If the pins need to be inspected to determine whether they can be brought back to life, I could order the pads and rotors from Rock Auto, then get calipers locally if they are found to be needed during disassembly.

Any input is appreciated!

brakes.jpg

2003 Ford Explorer Limited 4.6L 4x4 - 219K km
2008 Ford CVPI 4.6L - 133K km
2011 Ford F-150 Lariat S/C 6.2L 4x4 - 90K km
Re: Brake rotor rust - indicative of caliper issue? [Re: fsdork] #5432719 05/18/20 07:00 PM
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supton Online Content
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I think the pins are ok--when the freeze it's the inner pad that still moves. They might be sticky but that looks like rust that simply worked its way down over time.


2011 Toyota Camry, base, 2.5L/6MT, 206k
2010 Toyota Tundra DC, 4.6L/6AT, 160k
2003 CRV, 2.4L/4AT, 161k
1999 Toyota Camry LE, 2.2L/4AT, 225k
Re: Brake rotor rust - indicative of caliper issue? [Re: fsdork] #5432720 05/18/20 07:01 PM
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slacktide_bitog Offline
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Probably a frozen slide pin. You won't be able to get it out, so just get new calipers. Rock Auto has Raybestos Element3 all-NEW calipers at a good price. That would be my choice smile

While you're there, get coated rotors.

Re: Brake rotor rust - indicative of caliper issue? [Re: fsdork] #5432721 05/18/20 07:01 PM
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eljefino Offline
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It could also be the pad ears swelling from rust and getting stuck in their grooves.

You can clean up old pins, but if you nick their "teflon" coating, they'll corrode quickly and jam up again.

Best bet is to use the (new) brakes more, and give them a few good forceful stabs at speed now and again. If they install tightly, file or grind the ears.

Re: Brake rotor rust - indicative of caliper issue? [Re: fsdork] #5432725 05/18/20 07:05 PM
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GSCJR Online Content
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Yes. Incorporating a brake service twice a year would help to prevent this. Cleaning and lubrication should suffice.


07 3.5L VQ35DE NAPA FS 5w-20 ProSelect 21358 158KM
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Re: Brake rotor rust - indicative of caliper issue? [Re: fsdork] #5432726 05/18/20 07:06 PM
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MParr Offline
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Salt corrosion. It’s possible that the calipers can be saved by wire brushing and painting. That’s an awful lot of work and you won’t know if they’re salvageable until you get them off. You would be better served to replace everything. You are going to have a problem getting the bracket bolts out and they will need replacement too. If you buy from Rock Auto, go with Raybestos.


2019 VW Tiguan SE 2.0 TSI Now: Castrol Pro OE LL IV 0W20 & OE VW
2020 F-150 STX Super Cab 2WD 2.7 Ecoboost. FF & OE filter
Re: Brake rotor rust - indicative of caliper issue? [Re: fsdork] #5432760 05/18/20 07:39 PM
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Donald Online Content
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I think the outer ring of rust is nothing to be concerned with.

New coated rotors and high quality pads. Clean up the calipers including the pins. Wipe the pins clean. If rusty replace, don't wire brush.

Make sure new clips come with the pads.

Lubricate in the proper areas with right lubricant.

Amazon is a good place to also look for pads & rotors. Rotors are expensive to ship from RA.


2015 Ford F-250 w/Powerstroke
2016 Subaru Crosstrek CVT (wife's)
Re: Brake rotor rust - indicative of caliper issue? [Re: MParr] #5432773 05/18/20 07:49 PM
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hallstevenson Offline
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Originally Posted by MParr
Salt corrosion. It’s possible that the calipers can be saved by wire brushing and painting. That’s an awful lot of work and you won’t know if they’re salvageable until you get them off. You would be better served to replace everything. You are going to have a problem getting the bracket bolts out and they will need replacement too. If you buy from Rock Auto, go with Raybestos.

There's actually probably nothing wrong with those calipers. Surface rust like that is normal. You can clean it off but it will return....

Re: Brake rotor rust - indicative of caliper issue? [Re: fsdork] #5432784 05/18/20 07:59 PM
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92saturnsl2 Offline
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I've had brake rotor rust issues like that on vehicles/brakes that were meticulously maintained and well lubricated. Seems to me that it mostly occurs on vehicles that are exposed to the weather (not garaged) and/or salt and aren't driven daily where rust would be continually worn off. That's been my experience, none of my daily drivers that are driven regularly have seen this issue.


96 Grand Prix SE 150k Chevron Delo 5w-40 Synthetic
04 Odyssey EX 205k Shell Rotella T5 10w-30
96 Maxima GLE 275k Mobil Super HM 5w-30
07 Chrysler Pacifica Limited 4.0L 151k Rotella T5 10w-30
Re: Brake rotor rust - indicative of caliper issue? [Re: fsdork] #5432802 05/18/20 08:15 PM
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doitmyself Offline
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I think what he is asking is if the shiny clean area should extend closer to the rotor edge. If yes, then what is wrong with his calipers and/or pads that he is not achieving better contact.

Here's a picture of what I think we should be seeing (top) vs. the bottom picture which is more exaggerated than the OP
[Linked Image from i.stack.imgur.com]
[Linked Image from attachments.priuschat.com]

Re: Brake rotor rust - indicative of caliper issue? [Re: doitmyself] #5432824 05/18/20 08:49 PM
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hallstevenson Offline
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Originally Posted by doitmyself
I think what he is asking is if the shiny clean area should extend closer to the rotor edge. If yes, then what is wrong with his calipers and/or pads that he is not achieving better contact.

Here's a picture of what I think we should be seeing (top) vs. the bottom picture which is more exaggerated than the OP

The lip is caused (or allowed) by the pad design itself. It's simply not quite tall enough but on the other hand, I presume you don't want the pad to extend past the rotor's edge either. The caliper, and especially the pins, have no bearing on the pad being able to move 'up' or 'down', only side to side. The caliper bracket determines the brake pad's position though.

Re: Brake rotor rust - indicative of caliper issue? [Re: fsdork] #5432834 05/18/20 09:06 PM
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doitmyself Offline
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Yes, you are correct. Minute 2:15 on this video shows a pretty wide area on the outside of the rotor that doesn't get shiny: https://www.youtube.com/watch?v=PfyqNoR02FQ
Here's another video showing the same at minute 4:00 : https://www.youtube.com/watch?v=uvUzMwisLXU

I have never had rotors/pads with so little contact area.

Last edited by doitmyself; 05/18/20 09:13 PM.
Re: Brake rotor rust - indicative of caliper issue? [Re: doitmyself] #5432844 05/18/20 09:25 PM
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fsdork Offline OP
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Originally Posted by doitmyself
I think what he is asking is if the shiny clean area should extend closer to the rotor edge. If yes, then what is wrong with his calipers and/or pads that he is not achieving better contact.

Here's a picture of what I think we should be seeing (top) vs. the bottom picture which is more exaggerated than the OP
[Linked Image from i.stack.imgur.com]
[Linked Image from attachments.priuschat.com]


You are correct. The shiny clean area is narrow and does not extend nearly as far to the outside of the rotor diameter as the pads do, which doesn't make sense unless the caliper is not functioning correctly. That, or as supton suggested, the rust may have worked its way inward and swelled that visibly rusty area over time.

I do appreciate all of the replies. With that said, it seems difficult to pick out a common thread of a single likely cause of the symptom I am seeing on the rotor. Many good suggestions though.


2003 Ford Explorer Limited 4.6L 4x4 - 219K km
2008 Ford CVPI 4.6L - 133K km
2011 Ford F-150 Lariat S/C 6.2L 4x4 - 90K km
Re: Brake rotor rust - indicative of caliper issue? [Re: eljefino] #5432850 05/18/20 09:29 PM
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Originally Posted by eljefino
It could also be the pad ears swelling from rust and getting stuck in their grooves.

You can clean up old pins, but if you nick their "teflon" coating, they'll corrode quickly and jam up again.

Best bet is to use the (new) brakes more, and give them a few good forceful stabs at speed now and again. If they install tightly, file or grind the ears.


I saw this on my truck a few years ago, and the pad ears were very rusted.

Originally Posted by Donald
I think the outer ring of rust is nothing to be concerned with.



No its concerning, thats a good bit of lost braking surface area. Reduced braking efficiency.


13 elantra 84k 5w30 synpwr
03 chevy avalanche 83k synpwr 5w30
17 mazda cx-5 19000 miles m1 0w30
Re: Brake rotor rust - indicative of caliper issue? [Re: fsdork] #5432877 05/18/20 10:13 PM
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Dave9 Offline
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Up to you, the surest way to know if you need calipers is pull them and inspect for leaks, torn boot, and piston intact (not cracked/chipped if composite instead of metal).

Otherwise, the old calipers can have the rust cleaned off the mating areas to the bracket, pads. and reused, but you'd also want to inspect not only the pins for rust but also consider replacing the bushings if the pins are badly rusted as that may have worn them. Rock Auto sells both the pins and the bushings separately.

I'd not be too concerned with the prior wear pattern if you're replacing at least the pads and rotors, and pins and bushings if needed. Do that and clean up the rotors of rust and you're starting with a clean slate.

The thing to be concerned about is if the wear becomes this irregular early in the pad lifetime. Coated rotors will not make a difference in this respect, in a rust prone area all they're going to do is keep the interior cooling vanes more open which is most useful for towing or otherwise spirited driving with excessive brake use. wink I mean if you are concerned about hub-rotor contact rust, you can put some silicone lube there too. The coating will wear off by itself so eventually you'll need something, or to pull the rotors more often so they don't get stuck on.

Last edited by Dave9; 05/18/20 10:18 PM.
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