Brake question....at my wits end

Yes, the probelm did not start until I installed the new MC. I installed it and had this problem because at first, the rod WAS too long, and it behaved as stated above....hard pedal, etc. Then, I cut it down to fit as it should. But the still gets hard and stays at the top with the brakes dragging.

Coould I have messed something up running it at first with the pushrod too long??? As I siad, I have corrected te pushrod length and re-bled the brakes since....... Any thoughts?

 

when you bench bled the MC did you notice if it was pulling fluid back ?
that could be a simple test

 

I had to adjust the rod in my '74 when I added a power booster. I had similar problems: pressed on the brakes a whole bunch of times and it would pack up and I would get no brake movement at all. With the cover off and my faithfull assistant pumping the brakes slowly I ascertained that the plunger was covering the ports for the brake fluid to return, that is, the pushrod was too long. I took the mc off and let it relax. I then took a straw and cut two pieces that it were about 2/3 the length I thought I should have. Then I stuck one straw inside the other to make a combined piece that was too long and stuck it the mc:
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I then reassembled then dissassembled to allow the straw to "adjust" the correct length and cut my pushrod to this length:
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I have had no probs since. Yeah I realize that this is ghetto fab at its finest, but it worked. At least I think it worked - Jeep locks up fine and brakes dont drag.

Karl

 

does your brake pedal have any play in it? there is a little tiny hole in the end of the master cylinder if the push rod is too tight it can't draw air and will build pressure

 

Was your brake fluid old (or setting around in unsealed bottle-foil seal). Sounds like you have water in the brake fluid. If brake fluid sets it will absorb water (I don't think the synthetic does just the regular). When you drive the water heats and expands causing the unwanted pressure.

Just another thought.