580c new brakes peddle getting stiff

[fordtrucknut]

All new brakes from the top to the bottom, inside and out.
Adjusted the free play according to the manual.
I get one good brake press, then the next time I hit the brakes it might be extremely stiff and you have to stand on it to stop, then the next time i press them they might be good again, might not be.
Does the same thing in forward or reverse,
Does the same thing on the left and right individually, though the left does work better more often then the right.
I'm at a loss now.

 

[franklin2]

On my 480c one of the biggest problems I had after I fixed the leaks in the brake system was all the linkage was sticky. I had to take the floorboard out, and put penetrating fluid on all the moving parts several times, and then oil them up good to get it to finally work. The hydraulic pressure from the pedal and the master cylinders is strong, and can overcome a lot of resistance in all the linkage. But the small spring hooked down near each wheel cylinder is not very strong, so it can't pull everything back when it's so stiff with corrosion.

In other words, once you hit the brakes, they are being applied slightly after that since the spring can't pull the linkage back. So the pedal doesn't have much travel the next time you hit it. As an experiment, you can apply the brakes, and then take a deadblow hammer and manually knock the linkage back. See how much it moves. You can also activate the parking brake. See how the linkage moves, and then release the brake and see if all the linkage and arms move back to the proper position.

 

[fordtrucknut]

I put new springs on the peddle assembly, I'll throw a new set on the lower assembly too see if that works. I know they are not stiff at the linkage pins, I pulled all the linkage pins out, sanded and lubed when I replaced everything.
I'll report back.

 

[fordtrucknut]

New springs, no change, I tried bleeding again still same problem. When I pulled the springs off everything moved nice and free.
When the brake gets stiff , if I just hold pressure on it it will eventually go downtown the floor slowly.
Thought maybe the reservoirs were over full but it does the same with the caps off. Only thing that hasn't been replaced is the 8" rubber line on the right brake, and the hard lines.
The left brake seems to be working pretty good now after the rebleed, only getting stiff every so often, but goes down pretty quick if you just hold pressure. The right not so much. But if I do real quick presses of the brake it will free up and depress.
I should note, I'm not having any problems with the brakes disengaging, as soon as I let of the peddle they release, it is only engaging that is the problem.

 

[highwayghost]

I have seen rubber brake lines that the interior was coming apart and creating a 'check valve' effect.

 

[heymccall]

"Goes down to the floor when held"?

Internal leak at MC or brake cylinder is first hunch. Does the level remain the same after multiple tries?
2nd hunch is binding brake pistons.
3rd is binding shoe hardware.

 

[heymccall]

 

[fordtrucknut]

I should have said towards the floor, and engages the brakes slowly. Not to the floor as in a dead peddle.

I pulled off the slave and made a jig had a helper hold the slave down while I pressed the peddle, was still getting the hard peddle so that takes the shoe hardware out of the equation.
And I can pull up on the differential brake lever(item1) manually and it brakes the wheel.

Going to have a rubber brake line made tomorrow. As that's the last old piece in the puzzle.