We find no leaks, and the master cylinder is now a new one (posted that further down the thread). I'm going to have to think about that rod issue. I see what you mean. Nobody sells booster / master cylinder combo together, as far as I know. Do you know if the rod is adjustable for length? Frankly, i don't remember.

I'm also casting a jaundiced eye on that valve itself. It's 33 years old, and remember that brake fluid is hygroscopic, attracts moisture. So its internal springy dingies, if ferrous, may have been attacked by corrosion caused by moisture in the brake fluid.

 

Could bypass that valve and install an adjustable front / rear valve and do with out the light.
Why do you need a light to tell you the pedal is on the floor?????
You still have 2 systems not connected.
Dave ----

 

That was exactly my thought. The difficulty might be in losing its role in sending some fluid first to the rear (more volume of fluid needed) then to the front. But do other vehicles with disk front / drum rear have a fancy valve like that? I have never seen one on another vehicle. I need to research the idea. It would be nice to be rid of the contraption.

 

Woo-hoo! Carolina Classic Trucks has that valve, brand new. Yowza baby! Even Jeff's Bronco Graveyard didn't know where to find one.

https://www.carolinaclassictrucks.co...ake-valve.html
.

 

Is that one different than the one at the Graveyard?

Brake Valve

 

Yep, the Bronco one won't work on an F-250. That's what he told me on the phone. Mine's also an HD. All diesels are HD pickups.

 

Thanks. Good to know before I placed an order. I would have just assumed they didn't list all the models.

 

Heyyyy so uhhhh... did this work? I might have a proportional valve problem and might need this part for myself. Just wondering if it worked out?

 

Yes, the part from Carolina Classic Trucks did work. No more red brake warning light. You do need to get a little brass adapter on one of the brake lines.

Now I realize that at least one of my drums is not quite round. This was also contributing to the backs locking up too easily.

 

Hey, glad that new valve worked for you. I am replacing my old f150 proportioning valve with the one from bronco graveyard. Everything lines up perfectly as far as the brake lines go, problem is the old brake warning light sensor connector has two terminals, and the new one has one. Did you have the same deal with yours?

I have two pink wires coming out of the old connector. According to my diagram one pink wire comes from the panel and the other pink wire goes to the ignition switch.

Now if my troubleshooting logic is correct, a single terminal sensor or anything for that matter MUST be the LAST component in the circuit before it goes to ground. That means it must run from the panel to the ignition switch, to the dash light, and lastly through the proportioning valve sensor back to ground. My old sensor has two hot wires meaning it is midway through the circuit. That would mean that I would have to rewire the entire circuit to make it work? Anybody run into this before?

I don't mind not having a warning light but I was really hoping to make it work like it should...

 

If you look at the diagram again, the ignition switch is grounding the wire coming from the switch. The ignition switch has multiple sections, one section is a grounding section that tests all the warning indicators when the switch is sprung to the start position.

You can easily hook this up if you are not worried about the "test" feature when you go to start the truck.

Turn the key to run, you do not have to start the truck. Take your connector with the two pink wires, pick one, and ground it. If the brake light lights up, then that is the one you want. If it doesn't, ground the other wire. That should make it light up. When you find the one that makes the light light up, then hook that to your new proportioning valve terminal. Hopefully through some means your proportioning valve body is grounded. It probably is through the lines, and if it has a mounting bracket.

That's all you need. It will not light up each time you start the truck, but it will work if something happens.

 

I didn't get mine from Jeff's Bronco Graveyard, I got it from Carolina Classic Trucks. They said if my truck only has one wire to the valve, to connect the truck's wire to both of the wires on the differential valve. That's what we did, and I don't get the test light on startup anymore. Hope that helps!

 

After all that work, I was still getting rear brake lockup in the morning on our long dirt driveway. Especially the left wheel. After warmup, it was better. So I tried applying the brakes very gently down a gentle grade. Well, there was a slight pulsing of the brake effort that I felt. My master tech buddy said he suspected out of round drums were at fault.

Following his hunch, I ordered up two new rear drums. Amazon has them as low at $20 but they have got to be junk. I ordered Wagner drums from O'Reillys, using their price match to get them down to $55 each. That cured the rear brake issues. Everything is good now. I wonder if the previous owner had put Amazon $20 drums in there. They had a lot of weights tack welded on the outside. The Wagners don't.

 

They were probably turned too thin. I have had that happen before, they do not seem to check the drum specs at the shop like they do the rotors. The too thin drums will also give you a slightly spongy pedal.

 

Yep. Was chatting with my local tire guy about the case, and he said he just won't turn OBS drums anymore. Too much trouble with jobs coming back.