My never ending battle with my brakes....need advice please.

[tcs69rt]

So, I get another reman master cylinder (mc) for my 69 RT (stock discs & drums) and tell the store that I think it's another bad one. So, they wanted a shops opinion and I got a mechanic to confirm that it was bad to the store. We received another that I bench bled 3x and installed.

Then the garage put a hydraulic vaccum bleeder on it and very little fluid would come out of the right rear drum and the pedal is still soft & halfway to the floor. Could there be a blockage in the proportioning valve? When I press on the pedal and the mechanic opens the rear drum bleeder, pedal goes to the floor and nothing comes out. No visible leaks or loss of fluid in the mc or the lines. We did confirm that the pushrod length is good as it makes both reservoirs erupt. WE are scratching our heads. Opinions? Thanks!  TC

[charger Downunder]

flexible brake lines how old are they maybe they have collapsed, or ballooning out when pressure is applied.

[JB400]

Another thing is your brackets that hold the brake lines a little rusty?  If so, they can pinch shut

[Dino]

Yes the prop valve could be blocked, put another in and see how it goes.

[cdr]

does fluid come out of the left side?if it does then you have a problem with the right wheel cyl,or the steel line going to the right

[Cooter]

Yes the prop/combination valve COULD have a problem. If there's no fluid to the rear, then the "valve" inside that keeps you from losing front brakes if the rear are lost, will shift. Sometimes, the valve sticks and is a PITA to "re-register" to the middle again. If you have had the pedal pushed a bunch of times with the rear brake bleeders open and drained, this can happen.