Help with brakes?

[jdw]

I've got a 1972 c10 and developed air in the lines. Fortunately, the drums started smoking at a brake shop. Yeah, right. The shop replaced a couple of the lines that had rotted out, the master cylinder, and bled the heck out of them over the course of 3 days. Unfortunately, the brakes now function like coaster brakes. The pedal feels pretty firm, not soft and squishy. However, it goes almost all the way down and the truck just sort of rolls to stop. The shop owner was pretty cool and since he couldn't fix the problem didn't charge me for anything more than his cost on the master. I could only maybe understand about %40 of what he was saying and since I only originally went there for exhaust work I drove the truck back home. 350 horse with coaster brakes behind a cop scares the hell out of me.
Other than the basic mechanics, I don't know the first thing about brakes, I admit that. Before I start hemorrhaging cash I don't have, any suggestions on where to start? Slave cylinders? Booster? More bleeding? Since the shop I was at couldn't fix it (it's predominantly an exhaust place, and that work was excellent), I'd at least like to get some suggestions even if I have to take it into my preferred mechanic if I can't do it myself.
Thanks, guys.

[Rufton]

First I'd adjust brake shoes until they are starting to drag.
Then I'd pop top off mastr cyl (keep fluid topped off during bleed).
Then I'd crack each wheel cylinder and install a tube to see if each will gravity drain.
You can install a tube to wheel cylinder and reverse gravity bleed; full tube elevation higher than master cylinder.
Sometimes residual pressure valve or proportioning valve will interfere w/ gravity bleed; in that case you can bleed w/ a helper or pressure bleed.

If shop couldn't bleed they may have installed brake lines incorrect.

[Mister-B]

Where you're not real comfortable with doing the brake work yourself, and seeing as a pro had problems, it might be best to take it an actual brake shop.

It could be this exhaust place doesn't know their stuff, and therefore didn't properly bench bleed the new MC prior to installing it. Could be that you got a bum new MC that needs to be replaced again. I don't think it's the brake booster. If that went out, you'd still have brakes. They just wouldn't be power assisted.
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[Rufton]

I discovered a plugged flex line when rear wouldn't gravity drain; it wouldn't pressure bleed either. OEM flex lines may last 30 or 40 years. New flex line dry rotted in 6 years. New master cylinder stated leaking in 6 years. Defective new part very possible like Mr B said. Some bend new brake line such that air gets trapped in a high spot.

[jdw]

Hell. Thanks for the input, guys. Mr. B I fear you are correct.

[Rufton]

I just bough a new AZ master cylinder tonight.
$18.65 w/ lifetime warranty.
A little inconvenient but pretty cheap repair.

[cdowns]

the factory service manual is cheap // available as a hiquality reprint from most vendors and has an excellent step by step on how to do the brakes


me id b lookin first at your front disc brakes as they are designed to apply the most stopping power of the vehicle as compared to the rears