Both Rear Calipers Dragging

[joecool911]

I find it strange that both of my rear calipers are dragging. I smelled brakes and stopped to check them out. Both rear hot. Parking brake not on. Recently replaced pads and rotors. Sounds like caliper problems, but both at the same time?

Got home but the calipers were so hot that they'ed sizzle when you spit on them. Smoking. More left than right but both hot and dragging. Would this be calipers of portioner valve?

Edited March 8, 2014 by joecool911

[CTcummins24V]

When i bought my truck i had that problem and i had to replace everything...but i had a pinched brake line from the T at the axle

[Ilikeoldfords]

Maybe since you replaced the pads and rotors, the calipers are hung up from the pistons being so far spread with the new parts. I think these calipers are common to fail or hang up. Rebuild kits are really cheap. It is curious that both of them hang up at the same time though...

[joecool911]

Yeah, I'll tear them off tomorrow and try to rebuild. I already have the seals, boots and slide pin boots. Too bad I wore out a set if pads and kinda scored the new rotors. Live and learn.

[MnTom]

One way to help diagnose the problem is to jack up the rear axle (both sides) and see how hard the wheels are to turn. Pull one wheel and loosen the bleeder and see if there is any pressure. After you do that see how hard the wheel is to turn again. If it is a lot easier, then you bneed to check the hydraulic system. If it is the same then it is a caliper problem (anything from stuck pistons to stuck slides).

[joecool911]

One way to help diagnose the problem is to jack up the rear axle (both sides) and see how hard the wheels are to turn. Pull one wheel and loosen the bleeder and see if there is any pressure. After you do that see how hard the wheel is to turn again. If it is a lot easier, then you bneed to check the hydraulic system. If it is the same then it is a caliper problem (anything from stuck pistons to stuck slides).

Thanks Tom. That makes sense and easy to do.

Which side gets bled first? I've heard that the isolation valve will keep me from needing to bleed the front if I'm only working on the rear.

Edited March 8, 2014 by joecool911

[MnTom]

It doesn't matter which side to crack the bleeder on since the rear brakes are tied together.

[joecool911]

Come to think of it, problem could have existed when I toasted my last pads and rotors. But I had no idea as to its history. So I'm thinking that the calipers are not releasing and prematurely wearing the pads. Left side was a lot hotter, appears that the new pads are more worn and that's the side that ate the rotor down to about 1/8" of metal left before it got into the cooling recesses of the rotor.

[MnTom]

Come to think of it, problem could have existed when I toasted my last pads and rotors. But I had no idea as to its history. So I'm thinking that the calipers are not releasing and prematurely wearing the pads. Left side was a lot hotter, appears that the new pads are more worn and that's the side that ate the rotor down to about 1/8" of metal left before it got into the cooling recesses of the rotor.

HHHhmmmm, a CLUE!!

[JAG1]

I had this same problem on bothe rears. One was a long long way from home. I hit the caliper with a hammer at the same time while prying it open. It never acted up again.

Edited May 3, 2014 by JAG1

[flagmanruss]

I'm no brake expert...  but isn't there a common shared rubber flex line between the chaise & rear axle?  I've had rubber lines fail internally, delaminating & acting as a one way valve.  Since this is a common part to both rear brakes, it ought to be inspected. 

If you have the rear discs like my 01.5 and later, the parking brakes have their own set of drums inside.   

Edited March 8, 2014 by flagmanruss

[MnTom]

Yes, Russ, there is a single hose that goes from the left frame rail to the rear axle. I have heard of the hose failing internally, but have never seen one myself. I don't know how common that is. Another thing that I have seen (on my truck) was a brake line rust on the inside and plug the line.

Jag, DO NOT put 2 cycle oil in the master cylinder. It does not have the formulation to handle the conditions brake fluid does.

[Mopar1973Man]

Also it might be time to check the inside and outside diameter of the pistons and bores. I found that over time with heat cycles the brake fluid cakes up on the pistons and bind up the pistons. All you have to do is remove the entire caliper and pull the pistons and seals out.  Now drop check the piston in a empty bore. The the piston will not fall to the bottom on its own then the piston needs tuning. I typically take light grit sandpaper and lightly sand the piston. Clean and test again. Each piston should be snug fitting but always fall to the bottom of the bore without being pushed. The trick is the hydraulic pressure of the brake fluid will push the pads out but only the little wobble with attempt to push the pads so if the pistons at sticky then more than likely they will drag. About every 50k or 75k miles I got to break mine down and clean up.

[joecool911]

I bet my calipers are original. 180,000 miles. Will let you guys know how it comes out. Starting on it soon here. Gives me a chance to us my Motive power brake bleeder. I'll flush the back brakes too.

[Mopar1973Man]

Flush the brakes before you take them apart. Nothing like having fresh rebuilt calipers and flushing the dirty brake fluid out of the master cylinder into the newly rebuilt calipers.

[joecool911]

Thanks. Makes sense. Just didn't think of it.

[Mopar1973Man]

Really common mistake. I see guys blow up power steering pump and never flush the trash out. and Install a new pump to wonder why the new pump last for such a short time and fail again.  Same thing with brakes. Caliper jams up and replace with brand new caliper and pads and then whine about the brakes dragging again because they just flush all the dirt into the new calipers.

[joecool911]

I gotta get some clear tubing to bleed brakes. Anyone know the size?

[diesel4life]

Joe, didn't you buy a power bleeder recently? Or were you just looking? I'm about to pull the trigger on one pretty soon, gonna buy the master kit so I can do all makes and models.

[joecool911]

I have it and am about to use it for the first time. I'll let you know in a little bit how I like it. A bleeder tube came with the power bleeder. So I am good there. Although I just pulled the brake line off the caliper to bleed.

Fluid in master cylinder very dark. Here we go!!!

Edited March 8, 2014 by joecool911