Hey guys and gals I'm looking for some answers. I've been searching the web but still not all clear. Thanks for the help.

I've replaced my f250 booster and installed a 95 Explorer master cylinder and using the CPP proportioning valve. I also replaced all brake lines. Its coming together pretty good but I can't get the air out. I'm using a vacuum tool. And I did bench bleed the master before I installed.

I haven't hooked up the warning light switch. The CPP prop valve has 1 wire coming out and my original 68 brake junction has 2 wire connections. How do I connect this? Sorry if this is a dumb question

Also with this not being connected would it prevent the brakes from properly bleeding?

Thanks again for ideas and solutions
Kenny
1968 Ford F100

 

If the CPP brake valve is brass and is the one I think it is, it's a reproduction of a GM brake valve. It was originally made by Weatherhead. I don't know if the pressure rating of the metering spring and the proportioning spring inside the valve body assembly is the same as the Ford version of this valve but, the warning switch is definitely different in appearance from the Ford switch.

If you are still seeing air bubbles in the line of the vacuum pump, it could be legitimate that there is still air in the system. It could also be that the vacuum pump is pulling air in from around the bleeder threads or, the nipple of the bleeder screws where the vacuum hose is attached or, that air is being pulled in from around one or more of the new hard line flared connections --(connection(s) may not be totally sealed off).

I'm also not sure on the GM reproduction version of the brass Weatherhead valve but, on the Ford version of that valve, the small stem sticking out the front end (metering section of valve body) has to be pushed in to be able to bleed the air out the front brakes.

Not having the pressure differential valve switch wired up will not keep you from being able to bleed out the brakes. You just won't have any lighted indication if the pressure differential valve spool has shifted off center, due to an imbalance in brake pressure between the front and rear brake circuits.

 

The dash warning brake light with a P-valve switch is just a ground circuit. When the
P-valve inner spool rod is shifted off center from low pressure it bridges the ground circuit of the P-valve wired in switch.

Orich

 

Cool stuff, thanks guys.

Just bought another quart of brake fluid so here I go

 

Alright I'm getting closer. Found a couple problems.

I bench bled the master cylinder for the third time. This time I was real careful after bleeding it. I immediately plugged the ports to make sure no air could re-enter. And was careful when installing on the truck. This is huge.

Also I can get the 3 farthest wheels to bleed but the front drivers nothing. I'm positive I don't have a good flare on the line. So I will have to wait for some new line and make new flares.

I still need to wire up the brake warning switch in the prop valve. I need to think more of this. Orich great explanation but originally the F100 is a 2 wire switch and now I'm working with 1 wire. I know I'm a Dummie with this but?

Awesome, getting there. Ultarranger thanks for all the help during this process. I pretty much duplicated your set up.

Not in a big hurry with this. I still have to install the engine and finish the AOD conversion.

I would of never been able to do these things without the Internet and Forumns like this.

Thanks
Kenny

 

On the Fords, 1967 was the first year for tandem master cylinders and the pressure differential brake valve and the one wire brake warning switch. Starting in 1968 and later, the warning switch went to a two wire connector.

The two pins, however, are common since they are connected together by a small bar inside the switch connector.



The second wire off the circuit was tied to an ignition prove out circuit. When the key is turned to the start position, the brake warning light on the dash would momentarily light up. When the key moved to the run position, the warning light would go off. This was to let the driver know the wiring connection to the switch and the bulb were good and that the pressure differential valve spool was centered.

If the warning light stays on after the key is moved to the run position, then there's a hydraulic issue with the brakes that has shifted the pressure differential valve spool. This means there's a hydraulic problem with the brakes that needs to be addressed.

http://www.fordification.com/tech/wi...rninglight.jpg

If the brake warning switch isn't initially hooked up through the wiring harness connector, the valve can be checked with an ohmmeter, to determine if the pressure differential valve spool is centered or, if it's shifted off center.

If the spool is centered, there will be no continuity through the switch. If your meter has an audible feature, there will be no 'beep.'




If the spool is off center, you'll get a resistance value. If the meter has an audible feature, the meter will 'beep.'

 

Has anyone found brake-fluid compatible O-rings to rebuild the pressure dif switch? I mean the exactly correct size and material. The same switch body as shown above. Mine were trashed, and stuck, from a long-ago rear brake cylinder that failed.

Thanks. Kevin

 

Here ya go.

https://www.musclecarresearch.com/valve-kit-whead1