Both Rear Drums Sticking

[shawnmd]

I have a 69 Charger R/t with manual drum brakes all around. Front brakes are all new and work great. Rear brakes are in great shape, and work well for the first 5 mins of a drive. Then they start heating up, due to sticking or not releasing. I've pulled it in the garage right away, jacked it up and both rear wheels were locked..wouldn't move. After a few hours, they cool off  and pressure releases (i guess) and they can be turned again. 

My question is where to start troubleshooting...master cylinder? Distribution block? Proportioning valve? Wheel cylinders?

[b5blue]

Common for rear brake flex connector body to axle.

[Kern Dog]

Common for rear brake flex connector body to axle.

[shawnmd]

Common for rear brake flex connector body to axle.

Thank you. Is there anyway to visually tell if the flex hose has failed?

[b5blue]

No it swells up on the inside. Get the rears locked up like you said and open the line at the axle to see if it releases.

[6.7Cummins]

My 68 did the same thing and it was the brake hose.

[armor64]

i was able to get a 323 sure grip axle from a buddy going into retirement home care, that he has for decades. the rear hose was cut in half, but looked sealed completely inside, and the drums would not turn. starting the pull apart to see what i could do, i undid the remnant of the flex line and had some fluid push out, and like magic, both sides freed up and would spin together like nothing was wrong.