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Old 03-05-2019, 04:27 PM   #1
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What am I doing wrong?

I've done a lot of brake jobs in the past, but my van is giving me fits. Today, while inspecting the rear brakes, I discovered that once again, the inboard rear pads are worn out while the outboard ones are like new. Less than six months ago I replaced everything, the rotors, calipers, pads, slider bolts, shims, caliper brackets, etc. the guide pins were lubricated and had new boots, and a light coating of brake caliper grease was applied to all sliding surfaces. Prior to pulling the caliper today, it moved freely on the guide pins which still had a bit of grease on them.Upon removal I noticed that the piston seals have pushed out of the bore, likely causing the piston to not retract fully. That would hold the pad in contact with the rotor causing accelerated wear on that side. It's also possible that the master cylinder is not releasing fully. I've read that forcing brake fluid backwards when pushing the pistons in can damage a check valve, anyone know how to check for residual pressure? I've yet to pull the other side, but from what I can see, it's the same way. The photo shows the piston seals that have come out and may be preventing the Pistons from fully retracting. It's hard for me to believe that both sides have the same failure, but I got them at the same place. Other than starting over yet again, I'm at a loss. Id love to hear some ideas..
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Old 03-05-2019, 09:52 PM   #2
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Those seals look dry-rotted. Probably allowing dirt into the caliper preventing it from sliding freely. You need to rebuild or replace those calipers.
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Old 03-05-2019, 09:54 PM   #3
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Arctic, that is weird. Not sure of what's causing your problem but I definitely agree with Tim. Those need to be replaced.
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Old 03-05-2019, 10:02 PM   #4
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Having one pair of pads wear faster than the other is not unusual. Have seen it on several of my vehicles.
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Old 03-05-2019, 10:31 PM   #5
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The rubber on those calipers does not look like typical 6 month old seals. Looking at the picture again I'm wondering if the seals got cooked as the pistons didn't retract properly. Making them overheat and cooking the seals?

It reminds me that back in the 80's I had a '61 VW bus that the longer you drove it, the less the brake shoes released. The rear drums would be smoking after a few miles of driving. Like you I put all new brake parts on each wheel only to have the same problem keep occurring. It was pretty obvious in that old Kombi, with the little horsepower I had, that the shoes binding got worse the longer I drove it. If it sat a few hours the binding would go away, then build back up again as it was driven.

In the Kombi's case I figured out the rubber lines from the frame to the wheel were collapsing inside. I hadn't replaced those. Of course you could push fluid through them easily using pedal pressure, but they didn't allow the fluid to ease off like it was supposed to due to the restricted flow.

Just a thought. My '61 was only 20 some odd years old when the rubber in those brake hoses delaminated. Many Ford vans are around the same age now. It could explain why your brakes have been overheating.
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Old 03-06-2019, 04:05 AM   #6
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A couple weeks ago I did the rear brakes on a friend's F350 and one of the pins in the caliper bracket was froze up, not allowing an even squeeze on the rotor.
Bracket and pins at Autozone was about $58.

You should be able to easily pull the pins out after you take the bolts out of the caliper.
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Old 03-06-2019, 06:18 AM   #7
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Two common issues with Econoline brakes are calipers sticking if they sit for along time between uses, and the brake line issue that Shadetree mentioned of brake lines going bad inside, allowing the fluid to travel one way when brakes are applied due to the pedal pressure, but not spring back when pedal is released. Might at least try a new set of brake hoses if yours are older. Canít hurt and is t too expensive.
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Old 03-06-2019, 06:23 AM   #8
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What brand are your newer brake parts? Did you notice anything different when these parts were renewed, perhaps a bit of brake drag, accelerating and/or coasting differences? Slowing down too quickly?

How do the front components look in comparison?

There is a procedure known as "brake service bleed" which electronically triggers the ABS module which might be affecting your rear brakes. Big "might" though, just an idea.

Do you have any flexible brake lines between the ABS block and the rear calipers? What about the brake line tee blocks or connections?

Did this not happen before you replaced these parts recently?

Nothing specific from me but maybe food for thought.
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Old 03-06-2019, 10:54 AM   #9
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Thanks for the quick responses. As I mentioned earlier, all brake parts were new (well remanufactured anyway) all moving parts were free upon removal and found to still have a light coating of caliper grease, including most importantly, the guide pins. Clearly, the piston seals on the caliper are shot perhaps due to overheating. The passenger caliper looks fine, but the pads exhibit the same accelerated wear on one side. As for the "brake service bleed", despite repeatedly bleeding the brakes after the last brake job, I never felt as though the peddle was as firm as I thought it should be until a couple weeks ago when I was installing new front springs and mentioned it to the shop mechanic. He brought out his Snapon service tool, connected it to the OBDI port and cycled the ABS motor a couple times. Bingo, big improvement, now I have a better, firmer feel. I don't think this had anything to do with the wear issue though, since I only put about 1200 mostly freeway miles before I discovered the problem. So, now I wonder about the brake lines. I guess the only way to know for sure is to replace them and see what happens six months from now. Anyone have any ideas about the possibility of the master cylinder having a bad check valve, holding residual pressure? I know they are designed to retain a small amount of pressure to prevent excessive peddle travel upon initial application of the brakes, but could it be retaining too much pressure? Meanwhile, I guess it's time for yet another complete brake job. Anyone know where to source stainless hoses? Might as well upgrade if I'm going to replace them anyway. I know they made an improvement on my motorcycle anyway.
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Old 03-06-2019, 12:11 PM   #10
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That is a weird one...


1) Deteriorated 6mo old piston seals
2) Prematurely worn pads, inner only
3) Experienced guy, knows about lubing the pins, checking for bind


The deteriorated piston dust boots are probably a smoking gun, the square o-rings are likely overheated, as well.


I've had calipers drag, overheat the brake fluid (which expands) making things worse. Like Tim, I too have have older rubber VW brake lines turn into a 'check valve', allowing pedal pressure to apply the brakes, but not allow fluid to return freely to the MC, and acting as if I had a second residual check valve in the system. Drove me nuts until I figured it out. The culprit turned out to be an internally worn rubber brake hose. A $20 hose swap and re-bleed of the system fixed the VW.



My van's Dana 60 has rear drums (no picnic either) and only has one rubber hose from the chassis to the y block on the driver's side of the rear axle housing.



MC residual valve: I've not had one stick to where it increases the resistance to backflow, but I have had one become passive, not holding residual pressure at all. The symptom of that, is having to pump the pedal once to get brakes, even though you have new parts.



I'd also look at it rotor to caliper/pad depth, in so much as a change in fit after the last rebuild, where the new rotor is set at a different depth, the rebuilt calipers place the pads in a different location than the parts you replaced. Heck, maybe the wrong under pad shim or some spacer was left out. I've had this sort of thing screw me on a couple different racecars, very hard to troubleshoot. If the inner pads/pistons can't retract enough, and rub most of the time for some reason, they'd heat up, swell, get worse, heat the entire assembly until heat hurts parts. etc. Too tall of pistons in the rebuilt calipers, or a ridge built up on the pistons not allowing full retraction of the pistons in their bores, is something else I'd look at.


you got this!
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