Brakes Dragging

So I am having a problem with my rear brakes dragging. Passenger rear was dragging for the longest time and finally blew up on me. The secondary shoe on the passenger was down to metal, the rest looked fine. Sooo I got my rear axle rebuilt with new bearings and new shafts cause it needed them. Therefore eliminating bearings as being an issue. Then I went ahead and completely replaced the rear brakes with shoes, springs, and wheel cylinders. I also got the old drums resurfaced. I drove it around for a couple days and they were still dragging. So then I took the brakes all apart again and filled and grinded the grooves worn into the backing plate by the shoes thinking that the new shoes were hanging up on those. Slapped it all back together and guess what, still dragging. On my initial test driving they were dragging on the drivers side. I got home and readjusted the brakes, drove it, now they are dragging on the passenger side. I can also hear them dragging when I am on turns. Also on that second test drive the pedal was very low, slammed on the brakes, pedal came up. Drove a little more pedal was down again, slammed on brakes and came back up. Parking brake isn’t hooked up so that shouldn’t be the cause.
At this point the entire brake system front to back is brand new aside from the backing plates. Either I fix this or stop chasing my tail and do 4 wheel disks LOL

I am completely lost any advice is much appreciated.

 

What year/model you have makes a difference, but I'm wondering about adjustment given that they come "up" after a second application.

Also - How are you determining that they "drag?" Noise alone is not serious, may even be normal on 'new' brakes. Is any one drum hotter than the others, for instance?

If you hear them specifically on turns, then I am wondering about bearing adjustment, axle play, etc. Or even if you are hearing something else, and not actually the brakes.

 

Are the parking brake cables operating freely? Have you assembled the brakes correctly?

New self-adjuster parts? Are the backing plates worn out?

Suggest you don't try to adjust the brakes in the usual way. Instead, get the gauge and let the brakes adjust themselves with the self-adjusters.

https://www.amazon.com/GearWrench-3377-Brake-Resetting-Gauge/dp/B0002SQUJ0

This is how the pros do it.

 

73 Cj5 with the dana 44. I am jacking up the rear after driving and spinning the wheels. I can also feel a side hotter than the other by touching the end of the axle shaft. I’m setting them at an initial adjustment and then backing up and hitting the brakes. I would think bearings too but I just got all of that replaced. I can also smell brakes after driving.

 

Cables are operating freely. Brakes are assembled correctly I’m using the factory service manual as a reference. I filled in all the grooves that were worn into the backing plates. Self adjuster parts are 2-3 years old so not brand new.

 

Did you do anything to the hydraulic side of the brake system?

 

just rebled the rears. Master cylinder is a couple years old. Has all new hard and rubber lines all around. New wheel cylinders in the rear

 

I would drive it for a while, break them in and get the squoosh out of them and the 'fuzz' worn off.

Then check temperatures with $10 infra-red thermometer after cruising a few miles.

 

I'm starting to wonder about it being a hydraulic issue instead of a mechanical problem. Since it's happening on both rear wheels, I would look for something common to both wheels. That would leave the master cylinder, the single hard line to the rear axle as a place to start.

 

My thought was maybe the rear brake hose was bad?

 

Master cylinder is one of my ideas

 

Maybe. It is new

 

It’s happening on both rear wheels at different times, which is a little confusing

 

It almost sounds like a combination valve issue. Do you have one on the frame rail below the master cylinder? My old 74 had one, the other 74 not. Does it help release if you pull the pedal up with your foot?

 

I do but those are for the front brakes. No the pedal is all the way up already

 

Has the pushrod been adjusted any?

 

This. Is the master cylinder returning all the way to open up the ports? If the master cylinder doesn't return all the way, it won't vent circuit pressure to the reservoir. The trapped fluid in the circuit can expand as it warms up and cause the brakes to drag.

 

There’s no adjustment in the pushrod but I am missing the pedal bushing. Would the 16th-1/8th inch slop make that big a difference?

 

Just because parts are new doesn't mean anything. Many are very inferior and bad out of the box these days. I'm with the fluid side having an issue. Lines connected to the right ports and what rpv valves?

 

X10