Bleeding brakes-pedal pressure problem. Could use some advice/suggestions

[Flathead Fever]

I was a fleet mechanic for 30-years and have bled hundreds if not thousands of brakes. Every once in a while, you get one that's a pain in the butt, it's hard to get the air out of it. I would go ahead and adjust the rears as close as you can, you can go back and finish the rear adjustment once you have the brakes bled. Don't forget that the rear early Ford rear brakes you used have the long shoes towards the front, the opposite of every other drum brake on the planet. Adjust them up tight and then try bleeding the brakes. If it still causing problems, they make a visegrip with smooth edges that is made for clamping off hoses. Clamp off the rear brake hose and see if the pedal comes up, that way you can tell if the air is trapped in the rear or somewhere else. I have plugs for the master cylinder too. I can remove the lines and plug the holes, and the pedal should be rock hard.

When you bleed brakes pump the pedal slowly not fast. Pumping it fast can break the air up into tiny bubbles making it harder to get it out. You want to slowly push the air down the lines and out the cylinders.

[acchaplin]

Originally Posted by Flathead Fever

I was a fleet mechanic for 30-years and have bled hundreds if not thousands of brakes. Every once in a while, you get one that's a pain in the butt, it's hard to get the air out of it. I would go ahead and adjust the rears as close as you can, you can go back and finish the rear adjustment once you have the brakes bled. Don't forget that the rear early Ford rear brakes you used have the long shoes towards the front, the opposite of every other drum brake on the planet. Adjust them up tight and then try bleeding the brakes. If it still causing problems, they make a visegrip with smooth edges that is made for clamping off hoses. Clamp off the rear brake hose and see if the pedal comes up, that way you can tell if the air is trapped in the rear or somewhere else. I have plugs for the master cylinder too. I can remove the lines and plug the holes, and the pedal should be rock hard.

When you bleed brakes pump the pedal slowly not fast. Pumping it fast can break the air up into tiny bubbles making it harder to get it out. You want to slowly push the air down the lines and out the cylinders.

Soon as I get someone to help me, (son-in-law, and grandson were here on Sat) Might have to wait until next Sat for help.

I will post what my findings are.

This should be a SIMPLE task. A dual port MC, plumed into OEM front drum brakes, and rear drum brakes. That's it.

[paul2748]

Is the master cylinder a drum/drum unit.Disc/drum masters are different, most do not have a residual pressure valve built in.

[acchaplin]

Originally Posted by paul2748

Is the master cylinder a drum/drum unit.Disc/drum masters are different, most do not have a residual pressure valve built in.

Yes, I am pretty sure it's a drum/drum, non power MC. If I remember right, this pictulair MC was reccomended to me. Early '60's Mustang.

[glennpm]

Originally Posted by Flathead Fever

I was a fleet mechanic for 30-years and have bled hundreds if not thousands of brakes.... If it still causing problems, they make a visegrip with smooth edges that is made for clamping off hoses. Clamp off the rear brake hose and see if the pedal comes up, that way you can tell if the air is trapped in the rear or somewhere else

Just slip hose over the jaws.

[V8 Bob]

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Originally Posted by glennpm

Just slip hose over the jaws.

It really isn't a good idea to pinch shut brake hoses, as unseen damage can occur. The proper way is to plug the line or port with steel/brass fittings.

[Flathead Fever]

Originally Posted by V8 Bob

It really isn't a good idea to pinch shut brake hoses, as unseen damage can occur. The proper way is to plug the line or port with steel/brass fittings.

You are definitely correct. I was an ASE Master brake mechanic. I had mixed feelings about posting that. I only that a few times over 30-years years at work with special pliers with smooth clamps, no teeth, only tightening the clamp by hand just enough to close the hose so it didn't smash it and that that was usually on new hoses. I only did this when I was absolutely having problems getting a pedal to try and figure out where the air was at. We had some big trucks with aftermarket micro locks that locked the wheels up when the truck was parked and in use. They could be absolutely miserable to bleed. The one thing at work is I knew the brakes worked at one time, that all the parts were correct. When you're working on something like you're working on you need to make sure that the master cylinder brake rod is making through its full travel. That the pedal has the correct geometry, that the rod is being pushed all the way in. Once that's determined you can plug off the ports on the master cylinder and see if you have a rock-hard pedal, that way you know the master cylinder is good. You're trying to figure out where the problem is, master cylinder, front brakes, or rear brakes. When everything is correct and adjusted up it should bleed out quicky leaving you with a good brake pedal. I wish I was there to help.

[acchaplin]

Originally Posted by Flathead Fever

You are definitely correct. I was an ASE Master brake mechanic. I had mixed feelings about posting that. I only that a few times over 30-years years at work with special pliers with smooth clamps, no teeth, only tightening the clamp by hand just enough to close the hose so it didn't smash it and that that was usually on new hoses. I only did this when I was absolutely having problems getting a pedal to try and figure out where the air was at. We had some big trucks with aftermarket micro locks that locked the wheels up when the truck was parked and in use. They could be absolutely miserable to bleed. The one thing at work is I knew the brakes worked at one time, that all the parts were correct. When you're working on something like you're working on you need to make sure that the master cylinder brake rod is making through its full travel. That the pedal has the correct geometry, that the rod is being pushed all the way in. Once that's determined you can plug off the ports on the master cylinder and see if you have a rock-hard pedal, that way you know the master cylinder is good. You're trying to figure out where the problem is, master cylinder, front brakes, or rear brakes. When everything is correct and adjusted up it should bleed out quicky leaving you with a good brake pedal. I wish I was there to help.

Yeah that is what I seem to need! Someone to stop by that knows what they are doing, that "might see" with the (simple) problem is. Like I posted. This set up has worked in the past. Why all of a sudden now it's not!?