I'm at a loss..

[PrairieDrifter]

I've also seen where the rod under the dash was adjusted out to far, and caused drag issues similar to yours but that usually only happens after someone has messed with it.

It would be helpful if you had a IR heat gun and could take temps of each wheel when the symptoms are occurring, I'm just throwing that idea out there if you do have one.

No matter what the cause of the drag is once the shoes or pads if it were the fronts (not saying it is being hypothetical) heat up the rotors or drums the metal expands and the drag increase exponentially. Also if something is acting like a check valve (a bad hose) as others have indicated. Generally a bad hardline will leak, but if a hardline is crimped or bent it can sometimes cause a restriction.

Is it just one drum or both dragging. Also it would be good if you could tell if the fronts are dragging even if only slightly. Lets face it if it's all 4 involved, that could really narrow down your search.

Even if you think the play is enough in the pedal you could try adding a bit more as something free to try.

The fronts are always cold, not matter how far I drive, unless I'm heavy braking. The fronts are fine. I don't have a visual Ir gun, I've just got one of those laser temp guns.

Both drums are dragging but one gets hotter than the other. Much faster as well. Doesn't matter the adjustment. The axle hard lines are new and I haven't touched the other hardlines since I did my hoses, but they look completely fine.

 

[Redfish]

The proportioning valve cuts off flow to one section of brakes when it feels a loss of pressure. I haven't had a loss of pressure at the front since I've had the problem, we'll ever for that matter, as well as I have great working brakes. Maybe it could be slightly off, but no brake light and I never had a leak on the fronts.

I am not sure I agree with this...a proportioning valve limits the amount of pressure to the rear. The next quote below this one adds to my questions about that valve. If the fronts are always cold...they aren't getting enough pressure. Of course your definition of "cold" probably means "not excessively hot".


Another shot in the dark...some of the 3/4 ton and 1 ton squares had that proportioning valve at the rear that was actuated by a mechanical linkage. I have no personal experience with that, I know that some others on this forum remember this. It allowed more pressure to the rear brakes as the rear suspension was compressed with more weight. Does your new axle have something like that? I don't think they used it past the square body years but I don't know.

The fronts are always cold, not matter how far I drive, unless I'm heavy braking. The fronts are fine. I don't have a visual Ir gun, I've just got one of those laser temp guns.

 

[PrairieDrifter]

I am not sure I agree with this...a proportioning valve limits the amount of pressure to the rear. The next quote below this one adds to my questions about that valve. If the fronts are always cold...they aren't getting enough pressure. Of course your definition of "cold" probably means "not excessively hot".


Another shot in the dark...some of the 3/4 ton and 1 ton squares had that proportioning valve at the rear that was actuated by a mechanical linkage. I have no personal experience with that, I know that some others on this forum remember this. It allowed more pressure to the rear brakes as the rear suspension was compressed with more weight. Does your new axle have something like that? I don't think they used it past the square body years but I don't know.

While that may be the function of the proportioning valve in its normal state. I'm saying it's not malfunctioning, because when you lose brake pressure on the fronts or the rear, it shuts off flow to the low pressure side. Then typically the malfunction is it just getting stuck in that position. I'm not saying it can't be the problem though. But I don't believe it is, because i believe I would have the rears trying lock up on heavy braking and they don't.

Also yes, when I say cold I mean they're operating properly. Not dragging but still working properly. I did have a caliper start sticking, but I replaced that a few years ago already.

No load level valve. This is just a 12 bolt, i don't believe anything but a 3/4-1ton had that valve. Which would both be 14 bolts.

 

[PrairieDrifter]

Checked it after another shorter drive. Drivers side is smokin hot before the passenger side.

It can't be a hydraulic issue. They're both heating up but one at a much faster rate. It's gotta be ****** parts. It's just gotta be... I realize them being adjusted different side to side may cause the difference, but I've adjusted and readjusted and it just acts the complete same.

 

[WebMonkey]

While that may be the function of the proportioning valve in its normal state. I'm saying it's not malfunctioning, because when you lose brake pressure on the fronts or the rear, it shuts off flow to the low pressure side. Then typically the malfunction is it just getting stuck in that position. I'm not saying it can't be the problem though. But I don't believe it is, because i believe I would have the rears trying lock up on heavy braking and they don't.

Also yes, when I say cold I mean they're operating properly. Not dragging but still working properly. I did have a caliper start sticking, but I replaced that a few years ago already.

No load level valve. This is just a 12 bolt, i don't believe anything but a 3/4-1ton had that valve. Which would both be 14 bolts.

i typically don't jump in on the tech discussion since i'm sub-novice at best.

YES, my truck, 85 k20 HD option has two "2" compartments on the brake fluid reservoir.
one large, one small. the piston under them plus the reservois is the proportion.

the valve at the front is a "don't shoot fluid out the failed brakes" valve.
fronts have a hole, block it off. rear brakes have a hole, block it off.
also, light a light in the dash that you have a big ol' leak.

my 05 dodge ram, even the ford f-950 motorhome (don't remember what the actual number is) has ONE reservoir and has a prop block after.

my truck does have the load level variable valve in the back and it still works (thankfully)

as to the heat, dragging shoes but why?

agree it sounds mechanical rather than hydraulic but troubleshooting will be a front to back, back to front process of elimination.
i don't envy you

mine just had shot rear cylinders (and needed all the other consumables replaced)

good luck

'monkey

 

[Grit dog]

I am not sure I agree with this...a proportioning valve limits the amount of pressure to the rear. The next quote below this one adds to my questions about that valve. If the fronts are always cold...they aren't getting enough pressure. Of course your definition of "cold" probably means "not excessively hot".


Another shot in the dark...some of the 3/4 ton and 1 ton squares had that proportioning valve at the rear that was actuated by a mechanical linkage. I have no personal experience with that, I know that some others on this forum remember this. It allowed more pressure to the rear brakes as the rear suspension was compressed with more weight. Does your new axle have something like that? I don't think they used it past the square body years but I don't know.

I’m pretty sure those only came on 3/4 tons but great suggestion.

Another off the wall suggestion, do you have the pads on right and not swapped front to back?

 

[rusted nuts]

Checked it after another shorter drive. Drivers side is smokin hot before the passenger side.

It can't be a hydraulic issue. They're both heating up but one at a much faster rate. It's gotta be ****** parts. It's just gotta be... I realize them being adjusted different side to side may cause the difference, but I've adjusted and readjusted and it just acts the complete same.

Well You have 3 pages of stuff it could be that people have tried to help You with,, Time to stop saying it can't be And start looking for what it Can be. 1st thing i would do is pump the brakes up crawl under it and crake that hose above the rear Axle .I don't care if it is only a day old. It is a free thing to check.

 

[Bennyt]

Checked it after another shorter drive. Drivers side is smokin hot before the passenger side.

It can't be a hydraulic issue. They're both heating up but one at a much faster rate. It's gotta be ****** parts. It's just gotta be... I realize them being adjusted different side to side may cause the difference, but I've adjusted and readjusted and it just acts the complete same.

A few things come to my mind of things I would look at adjust.

Axle bearings bad, out of adjustment, bent tube, etc transferring heat to brakes?
Rent/ borrow a pressure gauge and check pressure at wheel cylinders.
Record the temps from your laser temp and measure the backing plate temps at different positions, 12 3, 6, 9, etc. Check axle/ hub temps and compare to another vehicle
If drivers side heats up faster/ first...I would pull and blow out the hardline with air and then rebleed.
Transfer parts side to side 1x1. Since you aren't running the parking brake or even if you were, I'd even see about swapping backing plates side to side if possible temporarily for testing.

 

[SirRobyn0]

Checked it after another shorter drive. Drivers side is smokin hot before the passenger side.

It can't be a hydraulic issue. They're both heating up but one at a much faster rate. It's gotta be ****** parts. It's just gotta be... I realize them being adjusted different side to side may cause the difference, but I've adjusted and readjusted and it just acts the complete same.

I think your wrong, but I hope I'm wrong lol. I hope that you change parts on the rear and it fixes it, but other than being over adjusted or springs out right missing I've never seen low quality hardware or shoes cause dragging. Hopefully I'm wrong and you get it handled replacing the low quality parts.

 

[PrairieDrifter]

I’m pretty sure those only came on 3/4 tons but great suggestion.

Another off the wall suggestion, do you have the pads on right and not swapped front to back?

Front disk rear drum. Short shoes on the front, rear shoes have the parking brake lever on the inside. All good.

 

[PrairieDrifter]

Well You have 3 pages of stuff it could be that people have tried to help You with,, Time to stop saying it can't be And start looking for what it Can be. 1st thing i would do is pump the brakes up crawl under it and crake that hose above the rear Axle .I don't care if it is only a day old. It is a free thing to check.

I'm not saying it can't be anything. It would just have to be an off the wall once in a lifetime thing. Everything I know about hydraulics and brakes, is why I've said what I've said. Nothing makes sense.

 

[PrairieDrifter]

I think you're wrong, but I hope I'm wrong lol. I hope that you change parts on the rear and it fixes it, but other than being over adjusted or springs out right missing I've never seen low quality hardware or shoes cause dragging. Hopefully I'm wrong and you get it handled replacing the low quality parts.

That's one of the other problems, I don't buy the cheap crap. I usually opt for the brand of my choice or one of the more expensive options.

 

[PrairieDrifter]

A few things come to my mind of things I would look at adjust.

Axle bearings bad, out of adjustment, bent tube, etc transferring heat to brakes?
Rent/ borrow a pressure gauge and check pressure at wheel cylinders.
Record the temps from your laser temp and measure the backing plate temps at different positions, 12 3, 6, 9, etc. Check axle/ hub temps and compare to another vehicle
If drivers side heats up faster/ first...I would pull and blow out the hardline with air and then rebleed.
Transfer parts side to side 1x1. Since you aren't running the parking brake or even if you were, I'd even see about swapping backing plates side to side if possible temporarily for testing.

The axle has all new parts except for the the center section and backing plates. Even the hard lines. New outer bearings and seals. It's 100% not transferring heat from the axle to the brakes. The axle stays cold, and the drums get hot hot in a a few miles. The drivers side drum gets real hot before the passenger side. Then it starts transferring to the backing plate then to the axle if I drive long enough.

The temp gun says it's hot lol. I don't even need the temp gun on a similar setup, for another vehicle. They're basically cold compared to my issue.

 

[SirRobyn0]

The axle has all new parts except for the the center section and backing plates. Even the hard lines. New outer bearings and seals. It's 100% not transferring heat from the axle to the brakes. The axle stays cold, and the drums get hot hot in a a few miles. The drivers side drum gets real hot before the passenger side. Then it starts transferring to the backing plate then to the axle if I drive long enough.

The temp gun says it's hot lol. I don't even need the temp gun on a similar setup, for another vehicle. They're basically cold compared to my issue.

FYI, I've seen some pretty damnn badly bent axles, and bent or rusted away backing plates. I've even seen it to where the axle wass run for so long that the shoes ate groves through the backing plate, but dragging brakes was not one of the issues. I'm just throwing out my observations from the shop.....

 

[SirRobyn0]

I'm not saying it can't be anything. It would just have to be an off the wall once in a lifetime thing. Everything I know about hydraulics and brakes, is why I've said what I've said. Nothing makes sense.

Right and unfortunately none of us are there with you. So we throw out our best advice.

Why don't you drive the truck until the brakes are dragging good. Reach under the truck and crack the bleeders for both the rear drums. If it's hydraulic issue there should be a good spirt of fluid and the brakes should free up. If it's mechanical inside the drum then they'll still be dragging and locked up.