So I finally changed the directional valve on my '72 Supreme (with the help of my buddy Mike), and the good news is, my dash brake light is no longer on. The bad news is, when we bled the rear brakes, we got barely a trickle of fluid. Hence to say at this point I have no rear brakes. So we removed the line from the wheel cylinder and at that point there was plenty of fluid coming out when I pressed down on the pedal.
I will also add that before, I had to step on the pedal very little and it was a hard pedal, and I never bothered to check the rear brakes because the car stopped good. Now I get about 3/4 pedal travel, but it's firm.

So a couple of possibilities we talked about are..
1) The wheel cylinders clogged with debris, thus not allowing the fluid to get to the bleeders, or...
2) The rear brakes are out of adjustment and the wheel cylinders are fully extending before the brakes are engaging and the fluid doesn't have a chance to get to the bleeders.

Thoughts?

 

You can take the wheel cylinders apart and clean them if there are no visible leaks. There are two actuators, two rubber cups, and spring behind the end boots.

 

Good job, Dave. You might get by with a thorough cleaning exactly as Eric stated - that would be the first choice if you have no leaks.

 

I have no leaks, and I'm going to replace them.

 

It's probably more cost effective to replace them vs. rebuilding them. Let us know how it works with the new parts.

 

I went through exactly this problem with a friend's 1972 Supreme. Even pulled the rear bleeder screws to verify that they were not plugged with rust. The problem ended up being rust inside the wheel cylinders that was blocking the port for the bleeder screw. I used a piece of copper wire to poke into that hole from the outside and not surprisingly lots of fluid came out. I advised him to replace the wheel cylinders, but he chose not to. You can lead a horse to water...

 

Just to save forty bucks? Weird.

 

That can't physically happen.

Replace the wheel cylinders. They're under $10 each at Rock Auto.
https://www.rockauto.com/en/catalog/...+cylinder,1952

 

Thanks but I've already picked up a pair.

 

^^^this.

 

Glad folks are paying attention. I missed that, too. Not possible.

 

Wheel cylinders replaced and all is 👍