brake problems..

[cleansquare]

Guys. I just wnt thru this with my 85 c20. I had lost rear fluid through a leaky MC and the proportioning valve shut the rears off, and I ended up having to get a new proportioning valve after a new booster and master cylinder didn't fix it. Huge pain in my butt.

Now I'm building the short wheel base 85. I replaced the front calipers, front rubber hoses, and rear rubber hose. I filled up the mc and let it kinda gravity bleed awhile so I wouldn't have to bleed so much later.

(Before I did that, the master cylinder was plugged and I slowly pumped the brakes with th mc cover off to get out any air that had entered when the mc emptied itsekf when I initially removed thr brake components.)

I screwed in all fittings into the calipers, rear axle and everywhere and tested them for snugness. After having my wife pump the brakes a fewtimes it became clear my bleeders in the back were stopped up. I had fluid when I'd crack the line but not in the bleeder. Pulled them and poked a cotter pin in there and voila, out came fluid.

Bled all 4 corners till blue in face. The rear never had more thsn a trickle, EXACTLY what the c20 did with a faulty proportioning valve.

The fronts had about 4" of squirt to them, not near as much as the c20 fronts had which would squirt fluid all the way to the inner fender.

I checked the prop valve little reset button and its not tripped. There NO light in dash indicating an imbalance or that the prop valve is tripped.

One thing that confuses me.

I couldve SWORE on my C20, that the front chamber in the master cylinder went to the front brakes. And the rear chamber to the rear. I coulve also swore that the lines entering the MC were different sizes so you couldn't mix then up.

Well, on this truck, the rear chamber was emptying fast while I bled the front brakes. The front chamber never moved. Nothing was really coming out of the rear anyways. When you took the cap off the MC and watched the holes in the MC while someone pushed the pedal, the rear chamber would squirt high but NOTHING out of the front chamber (rear brakes I think). Absolutely no movement in fluid. Or very very little when it would move.

Is this indicative of a bad MC?

The lines on the truck are thr same size fittings entering the MC. Coukd they have gotten mixed up? Would it even matter if they had?