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

[acchaplin]

Here is what I have.
Mostly early production '32 frame, steering, etc.
'53-'56 PU front brakes.
'39-'42 rear brakes. ALL the brake components are new except for the drums. They have been turned originals.
Front brakes are adjusted to a slight drag. Rears are not adjusted. (need 25-35 pounds of force applied to brake pedal)
Master cly I think, (bought it too long ago, you know, CRS) is a non power Mustang. Hardly any "free pedal travel")
Brake lines are 1/4" all polished stainless, with double flaired ends and polished brass T's.

Bleeding procedure. Master cly was bench bled by the instructions. Fill, until fludi starts to run out ports, then cap off with the plastic plugs. Short quick strokes until resistance.

Rears first. 5 pedal pumps then hold. Ran 1/2 a bottle of fluid thrugh. Got air bubbles, No hi pressure fluid squirts, just some soild dribble. The pedal would freely go to the floor.

Fronts, the same way. 5-10 sometimes 20, pedal pumps then hold. Got some air bubbles at first, then just some solid dribble fluid. Finished off that quart bottle of fluid.

Pedal would freely go to the floor.

I should ad, that there are NO visible leaks.

If I would pump the pedal fast and hard, I would get about a 1/4 pedal, and it would hold. Let up, pump again one time, pdeal would freely go to the floor.

Pump the pedal fast and hard several times again, get that 1/4 pedal. One could, with much difficulty, turn each wheel by hand.

What procedure am I missing here? Thanks

[kurt v]

don't know but have you adjusted the cyl so that the piston can come all the way back to pick up more of the fluid ?

[acchaplin]

Originally Posted by kurt v

don't know but have you adjusted the cyl so that the piston can come all the way back to pick up more of the fluid ?

Yes! There is just under a 1/2" free pedal travel.

[Bob C]

Sounds like no residual pressure valve.

[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]

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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]

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!?

[rich b]

Adjust the brakes tight; fronts with the star wheel, rears with the two top adjusters. Might be all you need to get a hard pedal; then go back and properly adjust the brakes.

Since you sound a little unsure on the master; maybe pull the boot back and make sure it is a 1" bore.

[acchaplin]

Originally Posted by rich b

Adjust the brakes tight; fronts with the star wheel, rears with the two top adjusters. Might be all you need to get a hard pedal; then go back and properly adjust the brakes.

Since you sound a little unsure on the master; maybe pull the boot back and make sure it is a 1" bore.

Yes, it is a 1" ID bore.

The reason I am unsure of what vehicle the MC originally goes to is I bought it 3-4 years ago. I was getting a number of items ready for a certain color at the local powder coaters. The MC was one of those items. I pulled the MC "innards" out in order, wrapped them in a brake fluid soaked rag then put that into a sealed plastic sandwich bag, then placed in the back of the cabnet untill I was ready for them here 3-4 weeks ago, when I assembled and installed the MC. After the MC was powder coated, I shoved a rag in the bore and sealed it with one of those plastic tubing plugs, then put the chrome bail and lid on, put all that into a plastic bag, and it went into that same cabnet.

I have run all the brakes up tight, like you sugested waiting for a family member to stop by and help me.

[deuce_roadster]

I would check what KurtV said first. You need a small bit of freeplay in the brake pedal so the piston comes all the way back. Also, if the MC sat for years with no fluid in it, perhaps it isn't working correctly.

[acchaplin]

Originally Posted by deuce_roadster

I would check what KurtV said first. You need a small bit of freeplay in the brake pedal so the piston comes all the way back. Also, if the MC sat for years with no fluid in it, perhaps it isn't working correctly.

I don't see why not it shouldn't be working. I sealed it up good 'n tight in the dark reaches of a cabnet I seldom go into,

[Kurt in NJ]

Does the linkage move the master cylinder piston through its full stroke?
Have the wheel cylinders been examined to see that the bleeder holes were drilled to be at the top of the wheel cylinders?
Have the shoes been fit to the diameter of the drums?
Has the centering of the shoes been checked?—-

[acchaplin]

Originally Posted by Kurt in NJ

Does the linkage move the master cylinder piston through its full stroke?
Have the wheel cylinders been examined to see that the bleeder holes were drilled to be at the top of the wheel cylinders?
Have the shoes been fit to the diameter of the drums?
Has the centering of the shoes been checked?—-

There is no "linkage",,,,,,,,,,,. Original pedal assembly, with a aftermarket MC relocation(?)/remount kit. Bracket bolted to the original holes in the K-member, allowed a later MC to be mounted.

The only thing I canged was the steel brake rod supplied in the kit. (goes from the bottom of the pedal va a clevis with the rod threaded into it, directly into the MC). Made it out of 304 stainless and added a little 1/4-3/8" to the overall lenght, and half dozen more threads.

There is no one around here that can do that "shoe fit to the drum" thing any more. Place was bought out in the early '90's. Just tell you to "drive aroun the block" several times, or "come down Cheat Mtn on 50 one time." They will be seated in no time.

As far as "centering",,,,, I don't know. The shoes and hardware mounted up only one way. Here is a picture, you can please tell me if you see something not correct. Thanks

[Lanny]

acchaplin, curious, are using glycol brake fluid or silicone brake fluid ?




.

[TJ]

You have the early rear brakes and did you adjust the bottom anchors? Also you powder coated the MC. Did you powder coat the lid? There is a vent hole in the top, is it clear?