Question about brake calipers

Boomer

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#1
Make
Chevrolet
Model
S10 pickup 4x4 4 wheel disc
Year
2002
Miles
153,000
Engine
4.3
I just did a rear brake job on my truck. I was hearing a grinding type noise. The passenger rear side inboard pad was all grooved up as was the rotor. I replaced both rotors and pads on each side. When I went to test drive it, I could tell it must be dragging because applying a little gas, the truck still didn't want to move. I had to give it more gas than usual. I only went for a short drive. A mile or less. I brought it back home and, it smelled hot. I took the tires off and the passenger side had a bit of scorching on the new rotor. I took the caliper back off and the piston was not all the way back. I got thinking that when I put it back on with the new brakes. I didn't have it pushed all the way back because I remember it was tight getting it on. I realize now, that should have been a clue. I pushed it back all the way.

With both wheels jacked up and tires off, I pushed the brake pedal. I then took it back off to verify release. It was back flush with the rubber around it. I started the truck and put it in drive. The driver side wheel started to turn, then stopped. The passenger side was turning. I'm wondering if maybe this is normal since the wheels were off the ground? I took the calipers off again to verify the pistons were back and they were.

I guess my questions are..... Can a stuck caliper be freed up and work fine or, am I just asking for it to stick again? I'm wondering if I should bite the bullet and put a new caliper on?

Also, is it normal the driver wheel stopped turning while the passenger side kept going? I mean surely the problem is on the passenger side since the scorching was over there and, the old pad and rotor damage was on that side, correct?
 

billr

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#3
More often than a bad caliper is a bad brake hose. They can develop an internal leak that makes the hose act like a check-valve. Pressure gets applied to the piston/pad, but doesn't release when the pedal is let up. There will usually be no external leak, so visual inspection won't reveal the problem.

Oh, I should also note that rear disc brakes often have goofy mechanisms to apply pressure to the pads via mechanical screws, levers, etc. Your pistons may need to be set back to a "home" position by rotating them. somebody else will have to advise as to the specified procedure.
 
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Boomer

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#4
More often than a bad caliper is a bad brake hose. They can develop an internal leak that makes the hose act like a check-valve. Pressure gets applied to the piston/pad, but doesn't release when the pedal is let up. There will usually be no external leak, so visual inspection won't reveal the problem.

Oh, I should also note that rear disc brakes often have goofy mechanisms to apply pressure to the pads via mechanical screws, levers, etc. Your pistons may need to be set back to a "home" position by rotating them. somebody else will have to advise as to the specified procedure.
Thanks Bill. That makes it tough. Seems like there is no visual indication. Perhaps it's prudent to change it. I didn't have time to test drive again after what I did. I will as soon as I have time.

Any word on that passenger wheel turning while the drivers wheel wasn't?
 
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#5
Because of the normal differential action ANY slight drag on one wheel (even normal drag from brakes or axle friction or whatever) will make that wheel stop and and the other turn. So what you see could be normal or not.

I experienced a similar situation recently and in my case the brake pad metal backing was just enough oversized (maybe a few thousands of an inch) and was dragging on the caliper solid housing so that it would not retract enough. Taking off a few thousands of an inch on the pad backing solved that.

If it is still hanging up, you can release the bleed screw and see if it releases. If so, than as Bill stated, it is p;robably a bad hose acting as a check valve.
 

Boomer

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#6
Because of the normal differential action ANY slight drag on one wheel (even normal drag from brakes or axle friction or whatever) will make that wheel stop and and the other turn. So what you see could be normal or not.

I experienced a similar situation recently and in my case the brake pad metal backing was just enough oversized (maybe a few thousands of an inch) and was dragging on the caliper solid housing so that it would not retract enough. Taking off a few thousands of an inch on the pad backing solved that.

If it is still hanging up, you can release the bleed screw and see if it releases. If so, than as Bill stated, it is p;robably a bad hose acting as a check valve.
Wow, the metal backing pad is pretty thin as it is. The drivers side was the one that stopped turning but, the passenger side is the one with the slight scorching and, also the one that ate up the old pad and rotor. The passenger side kept turning but, that was AFTER I made sure it was pushed all the way back in. I can try some more. I bought the Duralast gold pads from Autozone.
 
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#7
How difficult was it to push the piston in? When too much effort is required, the piston may be binding in the caliper and will not "pull back" that fraction of an inch needed to let the pad stop rubbing.
How tight is the brake pad in the bracket? If you had to force new pad onto place, it may be unable to "pull back" that fraction of an inch needed to let the pad stop rubbing.
How freely do the caliper guide pins move? If one is stuck and you ignore it, the "loose rotor" may let you install the new pads and fit the caliper over the rotor, but then jam against a pad when you install the wheel and "clamp down the rotor" against the hub.
 

nickb2

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#8
@billr and boomer, nothing very specific in these rear caliper, , just your normal piston and single seal and boot. From memory, aluminum body, steel piston. So that does sometimes cause a problem. Aluminum and iron/steel don't make good mates.

For 5$, you can get a seal kit for each caliper. But if you need to hone it cus the inside of the aluminum body sleeve is pitted or corroded, you are wasting your time, and a refurbished one can be had for 19$. These rear calipers are relatively cheap cuz they fail quite often. So tons if them out there. A semi loaded caliper can be had for 55$ or so per side. That is best cuz you get new guide pins and hardware.

Links below

https://www.thewrenchmonkey.ca/auto.../disc-brake-caliper-repair-kit/carlson/41160/

https://shop.advanceautoparts.com/p/wearever-unloaded-caliper-18-b4712n/10654228-P?navigationPath=L1*14921|L2*16461|L3*15684


As Dan wrote, if you can back in the piston easy with bleeder open, problem is as Bill said, collapsed hose or pinched steel line or something to that effect. But normally, from my experience, that almost never happens in the rear on these models in the rubber hose dept.

Chevy/GM trucks were very common for this phenomenon in the front hoses in this era and prior on the dual piston calipers as the bracket that holds it to the upper suspension table would rust and thus acting as bill said, like a check valve. The easy solution was to pry open the bracket to relieve pressure from the rust accumulation. Or just buy a new hose. Which I almost never do, just prying it open a bit works without having to have to bleed the system.

But like I said, the rear has nothing to hinder it. Almost never fail. But again, not unheard of. So check that out by opening the bleeder to see if the piston moves freely.
 

billr

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#9
What about "re-setting" the piston? Are these the kind that need to be screwed back to the beginning of the adjustment range when pads are replaced?
 

Boomer

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#12
How difficult was it to push the piston in? When too much effort is required, the piston may be binding in the caliper and will not "pull back" that fraction of an inch needed to let the pad stop rubbing.
How tight is the brake pad in the bracket? If you had to force new pad onto place, it may be unable to "pull back" that fraction of an inch needed to let the pad stop rubbing.
How freely do the caliper guide pins move? If one is stuck and you ignore it, the "loose rotor" may let you install the new pads and fit the caliper over the rotor, but then jam against a pad when you install the wheel and "clamp down the rotor" against the hub.

It wasn't terribly difficult to push in. As far as the pads in the bracket, they came with new metal pieces to put in so I used them. I'll check them on each side. The pins on this thing are really just small bolts holding the caliper to a bracket assembly that holds the pads. They don't come all the way across to the side that holds the outer pad. The bottom of the rotor does want to tilt outward a bit until I put the wheel on though. The drivers side does NOT do that.
 

Boomer

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#13
I retest drove it tonight. At least now when I put it in gear, it moves on it's own. The first time before I had that piston pushed all the way back, I had to give it some gas to get moving. I thought for a second the tranny had gone out. It still smelled warm when I got back though. I pulled the wheel and caliper again to see if the piston was back and it was. Do to my schedule, I only have a little bit of time to work on it this weekend.

The outer pad backing has come off though. It stayed in there with the caliper on because it had no choice but, it's completely free of the pad. I even tried securing it by pounding the little tabs down tighter.

Can I just run without that metal backing plate on the outer pad?
 

nickb2

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#14
Can I just run without that metal backing plate on the outer pad?
yes, you can omit that shim on the outer pad, it has no other application other than to reduce vibration noise.

Often, I have clients that hardly ever use their cars or trucks, the anti noise shims that you are talking about that cover the back of the pads will either move around, shift, or even worse, rust through.

One particular client the other day complained of sponge pedal. Disk and pads were fine, but shims had rusted so bad, it was like braking on a pillow, hence the rust was creating an effect of something like having air in the system.

I simply remove them and tell the client they may get some squeal noise, but usually, it is fine. What I do in these cases, when the shims don't work/ fit, or just plain not existent cus they are now rust dust or don't come in the box with the new pads, I use disk brake quiet stuff from permatex. It is a blue coating you can put instead of the shims. It helps reduce the vibration that cause noise/vibration.

Even when I use new shims, I still put this stuff on EVERY SINGLE job I do. Much less come back later for squeal noise. For ten$, I pass a can a week. For a do it yourselfer like you. 1 can will probably rust out on your work bench before you go through the whole thing.

Another thing I do, I DON"T use use the grease provided in the box, even OEM pads. I use the purple stuff, again, from permatex. It's just a preference of mine. Remember. I do this all day every day. It's my day job. So I have figured out that certain products just work. Others don't.

Permatex has been a very good company, cost effective for high volume shops, and great at packaging their stuff in individual size packages for single applications.

I do not own any shares in this company, I just think they make good stuff.

https://www.canadiantire.ca/en/pdp/...QgqEAYYASABEgLaz_D_BwE&gclsrc=aw.ds#store=247
 
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nickb2

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#15
BTW Boomer, correct me if I am wrong, but wasn't it you who had a brother with a nice old/vintage gm? How is he and how are you? Still working hard at the factory?

I love this vintage tune.