brakes driving me insane

[LMREESE]

67 swb drums all the way around. I only have about half pedal or maybe a little less. New wheel cylinders new shoes New master cylinder. I adjusted the brakes, bench bled the new mc and bled and bled and bled the brakes with no better results. When I changed the mc there was a half inch of sludge in the bottom, could this have clogged the proportioning valve and causing me to not have petal? Any other ideas? I forgot to mention the truck does not have power brakes.
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[AirSpeed]

Originally Posted by LMREESE

67 swb drums all the way around. I only have about half pedal or maybe a little less. New wheel cylinders new shoes New master cylinder. I adjusted the brakes, bench bled the new mc and bled and bled and bled the brakes with no better results. When I changed the mc there was a half inch of sludge in the bottom, could this have clogged the proportioning valve and causing me to not have petal? Any other ideas? I forgot to mention the truck does not have power brakes.
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I don't know if that's your problem but I would certainly replace the prop valve if the master cylinder was full of crap. The valve doesn't take much to render it useless. If the piston in the valve is stuck and you lose pressure somewhere in the system all you brakes will fail. I bought one on EBay for I think $60, it came with the mount, the plumbing and the harness to hook it to the warning light.
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[SS Tim]

The combination valve may very well be the problem and they are non-serviceable. You did not mention the lines. Did a lot of debris break loose during flushing/bleeding? Did you replace the flex hoses? A swelling hose under pressure can do this and is very unsafe. I'd change the valve and flex hoses. Flush and inspect the lines then see what you have. When is is working to spec. Then consider a power booster it was a dealer bolt on option.

[joel.e]

Since you changed all the shoes make sure they are adjusted out enough. Just changed all mine this past weekend and had the same problem. Adjusted the shoes out until they started to drag and it fixed the pedal.

[LMREESE]

I adjusted the brakes till I got some drag when i installed them. It just started doing this one day thats why I went through all the brake system. When you said the proportioning valve wasn't serviceable does that mean I cant try to blow the junk out if there is any? Also I haven't been able to find a new valve only ones for the disc brake trucks.
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[SS Tim]

To start off we need to clear up that it is a distibution block with a warning switch function and not a proportioning valve. My understanding is that it is a spool valve that slides as a function of a pressure differental between the brake circuts to ground the light circut. Chevrolet in its manual advises that it is not servicable. Generally that means you can't take it appart and reassemble it without damage. It does say to clean it if in doubt. If you feel you need a new one go here. http://inlinetube.com/Prop%20Valves/PR-111.htm
Otherwise a used can possibly be found on the classified boards.
My thoughts were that the valve may have pushed over and not recentering. Is the brake light on? Does the brake light even work on startup bulb check? If you are not sure run a test lamp from "B+" to the block's switch terminal with the wire disconnected.
Basically again, I'd first try cleaning everything and really flushing it if you didn't, brake fluid is cheap. Hoses are a very important part that should be at least inspected and probably replaced. Shoe adjustment is important but it sounds like you are close there.

[GuyO]

Um, before you replace parts make sure the valve is "centered". You can use a C Clamp to keep it held in. With the valve centered make sure all your hoses are below the bleeders. I have had to wire them down so that the air bubbles go up! Providing the proportioning valve isn't defective that should do it. Good luck! G.