I got a 1977 ford f100 392 engine with manual brakes that want build up a pedal no matter how much u bleed it or pump it .it builds up an as soon as it sets a few minutes no pedal straight to the floor it goes ..any help would be great ..new master cylinder new wheel cylinders on back new calibers on from new brake shoes new brake pads new brake lines from med way of truck to back ..only thing not new is brake portion value even rubbers lines are all new none of these parts are reman all new ..

 

If you're not leaking fluid anywhere, I would tend to think you have a bad M/C as the fluid seems to be going past the piston inside. I've had that before, the "new" M/C has sat on a shelf, and the rubber o-rings stick to the inside and rip when it first moves. I would start there.

 

Did you bench bleed the MC?

 

You need to activate the pressure differential valve to properly bleed the fronts. You can also try pumping up the brake pedal, and then cracking the line connections at the master cylinder loose (one at a time) to see if any trapped air will expel.

 

Once I bench bleed mc an all the lines had a little pedal ..once I let it set 5 to 10 minutes it has no pedal an goes straight to floor everyone says its aur in line but I cut bleed it as well still no pedal

 

Not 100% sure on manual brakes, but on power brakes there is an adjustable rod behind the master cylinder. I had the same issue no matter what I did until I adjusted that rod and now....PERFECT. Has to be just right, too short = no brakes, too long = tap the pedal and you hit the dash.......

 

Ok so far I have gotten a little brake pedal an it stops the truck but u got to pump it ..bleed some more air out pedal is getting better but pedal is not traveling up from floor like its surprose to ..once I pull it up it has no pedal at all steight to the flood they go u until u pump them again..then your pedal is back

 

Any idea of why It lose pedal would be great once u pull foot pedal up from floor what ever brake pedal u had goes away

 

All I can tell you is that I replaced my hard lines, MC, booster, and flex lines to the front discs. It took me forever to bleed all the air out. I went through 4 large bottles bleeding. I couldn't get it at all just doing it the normal way. What worked was putting a vacuum pump at the bleeders, but even then I had to do each bleeder twice.