I will tweak this today and see what happens. Thanks!

 

I checked the plunger thing... Its exactly 1" out as indicated. Purchased another, new master cylinder; got a higher grade than what I had. Bled the hell out of it till no air and then some... Then i did so on the truck.

Still pumping for brakes. I could be wrong but after 4 master cylinders which I have done these same steps with, and the problem remains, it seems to me something else is the issue... How about my plumbing?



The is my proportioning calve... The hoses are routed as such:

Front 45° port - front axle
Forward verticle port - aft master cylinder port/rear port services front brakes
Rear verticle port - forward master cylinder port.
Rear horizontal port - rear brakes

Is this right? Thanks!

 

Looks like the front lines are wrong. The lower port is missing/plugged.

There should be 5 lines in total.

I know this doesn't exactly show an easy to see diagram but hopefully someone has a better example.

 

Normal plumbing routine for a combination valve. Although the designation of front or rear of master will depend on the master cylinder layout as some flip the chambers for front and rear. if you have one of the older cast M/C the larger reservoir chamber is for the front disc brakes.



If you have to "pump up" the brake pedal you have air in the system.

 

Thanks for the pic! Reminded me where to look for this one. Only posting it 'cause it names the front outlet locations.... although it probably doesn't matter.

 

This is an educated guess but the fifth port referred to on the bottom front of the valve looks like it is for later TTB trucks where the lines for each front brake run directly to the valve. The plug was installed on this one when I grabbed it from the 79 bronco which had the solid axle.

I took great care to meticulously bleed the current master cylinder and the entire braking system. This is not to say a certain amount of air isnt trapped in there somewhere but IMO its unlikely but I really dont know what else to do; yesterday I took my time and spent several hours to do it as correctly as I know how to.

Let me ask this.... When removing the bleeding hoses from the master cylinder, what is to stop air from getting into the mastercylinder?

 

This pictured layout is correct for your 2x4 truck from the factory manual. Separate line for each of the two front brakes.

The weight of the fluid in the master cyl keeps the air out of the master but there is still air at the connection. Thus bleeding the system is needed.

Your front brake lines should have been two separate lines to begin with. Did you change out those when you installed the other components? There is a tee somewhere?

.

 

I did change the lines as part of this project... There is a single flexible line that is secured to the frame rail which has a t-fitting which is secured to the pumpkin. The lines for each side connects to this.

I bled the system after I connected the master cylinder... I didnt know if there is a tendency for air to get in when braking the connections from some sort of burping effect.

I spent over an hour bleeding the master cylinder. I was even careful to coax some stubborn little bubbles out of the interal ports with a clean pick.

I guess I can take it to a brake shop which would be a waste of money if they are only gonna do something I could other wise do. The problem I have with this is I have some other upgrades to do to the system; before I move on I am simply trying to confirm all my stuff works right.

 

I did change the lines as part of this project... There is a single flexible line that is secured to the frame rail which has a t-fitting which is secured to the pumpkin. The lines for each side connects to this.

I bled the system after I connected the master cylinder... I didnt know if there is a tendency for air to get in when braking the connections from some sort of burping effect.

I spent over an hour bleeding the master cylinder. I was even careful to coax some stubborn little bubbles out of the interal ports with a clean pick.

I know it goes against conventional wisdom but I am gonna change out the proportioning valve. I have checked and verified all other components in the system to be working properly although the air in the master cylinder remains a possibility however remote. Hopefully I can find the problem by process of elimination. If this doesnt correct it then it confirms the air hypothesis. Since this one is 30+ years old and a replacement is $15 its a logical, cheap and easy issue to rule out no matter how unlikely. Will keep you posted.

 

Maybe.... But this is the way the factory designed the braking system for our trucks. Those pics I supplied were from the FACTORY MANUAL. The way you have it is wrong. If it was a good idea then the Ford Designers would have done it that way; which they didn't. Good luck!

I'm not saying it's not a possibility your proportioning valve isn't bad but plugging a line port and your line redesign is.

.

 

I meant I replaced the lines, not the configuration... This is a 4x4 truck... I have seen the same configuration on quite a few solid axle 4x4s... I am sure it is factory. I didnt plug the port; it was like that from the bronco I pulled it from.

 

Not to hijack but I replaced drums, wheel cylinders, 1 line, shoes, pads and MC and bled the brakes and never touched the prop valve and my brakes are great. Just didnt realize that pulling that pin was required, what does that do? Thanks

 

I've never read a real explanation but I think it is to reset the warning light pin and to put the ports in the correct position for bleeding after a partial system failure where the warning light was activated. Just guessing though.....

.

 

Bama - what year? I read on a bronco site it will work with H block. Modified the hard lines to fit the prop valve but thinking maybe I should do that...

Just got the prop valve from pnp and heading home to try it out.

Did you have a b1tch of time bleeding your new mc?

 

crazy96863 I owe you an apology! Apparently for 1976 F150 4x4 they used a single line to a block like you described.