Hydraulic Brake Mystery

I could use a little wisdom here:
New T build all new brake lines and hoses, New master, I did the old bleed, bleed and bleed some more. No air and the peddles firm. let it sit one minute and the peddle goes to the floor - So I bled some more - No air - Pump them up good brakes - let it sit goes to the floor. I suspected a bad master, replaced it and same thing happens. Any ideas?

Drum - Drum brakes / GM manual master.

Thanks, -Don

 

Is there residual pressure valves installed?, if the m/c is below the wheel cylinders you will need them.

 

i say bad master cylinder to, if after you bleed the brakes you hold your foot on the pedal ever so lightly can you feel the pedal moving down, thats how to tell if your master is bypassing, bad master.

 

Nope, and master is above wheel cyl. Its a pretty basic set up.

 

Yeap - Thats what I thought as well - replaced the master with another new one - but same - Im baffled

 

ok also do you have the brakes adjusted up correctly?

 

Hiya,

Try the link below....it should help...

http://ecihotrodbrakes.com/brake_facts.html

 

It sounds like you do not have enough stroke (not pushing cylinder in far enough)

 

Good question, the fronts are 40 ford and the backs are 60 sumpin ford PU, so the rears self adjust I am good with that but the fronts???? I thought I did - but back to the garage I will try that and get back, thanks for the brains guys I just didnt want to overlook the obvious - go to the HAMB!

 

It all points to adjustment. In a closed system what you are describing is classic pressure bleed off as the springs pull the shoes back to position. Adjust all brakes till you can't move the wheel s and see if it still does it. If not then back off the adjustment until you can just turn the wheels. Remember 40 juice brakes have individual adjustments for leading and lagging shoes.

 

I think jrsiron could be right ,a friend of mine messed around for weeks with the same problem.Turned out to be the ratio on the pedal rod into m/c.

 

You say its a NEW build so I assume it hasn't been on the road yet.

The rear brakes self-adjust for normal wear IN DRIVING.
The initial adjustment of the rear brakes, even with self-adjusters, must be done manually.

You most likely know that...but I figured I'd throw it out just in case...

 

And 39-41 Ford brakes have 4 adjustments per wheel. First the anchor pins at the bottom for the major adustment and then the top for running adjustment.

 

YOU GUYS ARE F*CKIN GENIUSES!! Thats exactly what it was front brake adjustment, Got em set bled it once more and just got back from a putt, it works great. Thanks for all your help. Once again the HAMBers save the day!
Have a safe Fourth everyone.

-Don