I have a highboy and it has drum brakes the way around and I would like to convert it to disk later on , but the proportioning valve seems to me giving me fits and I am not able to find an all drum valve . Will a disk one work as well or should I rebuild the one I have ?

I wave in voided some pics , it has 5 ports 2 in 3 out

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that is not a proportioning valve it is the switch that turns on the brake light on the dash you don't need a proportioning valve with all drums
roscoe

 

Like rosco said. That's just a junction block

 

Exactly what is happening?

 

Are you sure your rubber brake lines aren't acting up by collapsing inside?

 

Brakes work , no problems there so far , just the Damn light is on all the time .
Just needing idea of what to do .

 

Pull the wire plug and the light will go off. There is a small pin inside that will shift from CENTER to either side incase of a leak on that side. If you have no leaks you can unscrew the switch and re center the pin with a small screwdriver.

 

Hey fab man , thanks for the tip , I will do that in the morning . And how do you get the vet zone on my stuff US NAVY ret here

 

Welcome to the ZONE and thank you for your service! This link will show you how to join the vet forum: https://www.fordtruckzone.com/threads/how-to-join-the-veterans-zone.655062/

If you get the pin re centered and the light comes back on, you most likely have a small leak in one of your wheel cylinders. You can find the culprit by taking the drums off and looking under the rubber "boot" of the cylinders. If you find any brake fluid under the boot, that will be your leaking cylinder.

 

Ok I will look there at them , thank you for the information .

 

Geez Louise, this is not a junction block!

The following introduced in 1967 along with dual master cylinders.

EVERY Passenger Car, F100/350, Bronco and Econoline with disc or drum brakes has a similar valve thru the 1990's.

FoMoCo: This is C8TZ-2B257-C .. the Brake Pressure Differential Valve that some people call a proportioning valve.

1968/75 F250 4WD

C8AZ-2B264-A is the Brake Pressure Differential Valve Warning Lamp Switch that threads into the valve.

1968/69 FoMoCo Passenger Cars, 1968/79 F100/350, Bronco & Econoline.

This switch is a notorious POS, it's obsolete but is available NOS and from auto parts stores.

 

Bkw , thank you , now I can chase this down better , lmctruck.com has the switch so I will order a new one later . Thank you so much for the help .

 

My switch went out about. ...8 years ago ? I unplugged it ....
I know, not a fix. No light thought! .
It's a differential valve for sure.
I consider it as an idiot light for people that don't know chit about vehicles.