The Stovebolt Site Forums The Shop Area Driveline Brake issues

Just bought my ‘46 and the former owner replaced all the brake lines, replaced the master cylinder, all 4 wheel cylinders and new brake shoes᠁..but he couldn’t ever get the brakes bled out. Now I’ve taken up the job and I can’t get them going either. Everything appears to be done right. There are no leaks. If you pump the brakes about 10 times, you finally get a pedal. In my old school shade tree experience, that indicates air in the lines. But I have bled them several times, and just can’t get them to work. What could I be missing???

Maybe the pad return springs are collapsing the wheel cylinders all the at down and the reason you need to pump so much is because that’s how much fluid is needed to push the pads all the way out to the drums
The system needs a residual line pressure valve that holds a the pads out with a fixed pressure but also the pads themselves should be adjusted all the way to the drums so that the return spring is almost home when there is no brake input
The residual line pressure valve is meant to match the return spring pressure
-s

Power bleeder or start from the master cylinder and make sure it is bled. Pump until you get pedal and hold. Passenger rear is next, bleed, check fluid level. Pump until you get pedal and hold. Then drivers rear, bleed, check fluid level. Pump until you get pedal and hold. Then passenger front, bleed, check fluid level. Pump until you get pedal and hold. Then drivers front, bleed, check fluid level. Never let off pressure with a bleeder open. Good luck.

Could be that the former owner bought the wrong parts. Or the supplier sent the wrong parts. Did you check?

BTW, welcome to the site!

Huck brakes have two adjusting stars per wheel cylinder. Each adjusting star adjusts only one brake shoe.
Before I bleed a Huck system, I tighten one star until the drum won't turn. I them back it off until I can barely move the drum by hand. I then tighten the other star on the wheel cylinder until I can't turn the drum, then back it off until I can barely move the drum by hand.
I do this on all four wheels. Why? because I want to eliminate as much free play in the shoes so that the master cylinder has enough residual brake fluid in it to put full hydraulic pressure to the wheel cylinders. I then bleed all of the wheel cylinders. I then adjust the wheel cylinders as per The Book, except that I have them set tighter than their specs (fewer clicks away from felt significant drag). Doing it this way encourages the drums and shoes to machine themselves to a matching arc.
So you might ask, "Carl, why doesn't The Book tell us to do it that way?"
It is because the book assumes that you have new drums and new shoes which have matching arcs. The Book does address how to correct a mismatch of arc between drum and shoe, but it involves grinding shoes to match the drums. Something which I don't want to do.

The shoes probably need adjusting. The Huck brakes are different then any others. There are 2 adjustments on each wheel. They all have right hand threads. Turn the adjustments away from the rods till the drum gets hard to turn. Then back it off about 5 notches. You may have a little drag but that is OK.

George

Thanks guys!! I spent all afternoon making sure the brakes were adjusted out properly᠁᠁then re-bled the brakes 3 different times. Right rear, then left rear, then right front and left front last. Used an ez-bled system on it. Still no brakes. If you pump them several times, you get a pedal and it’ll stop the truck. But next time, the pedal goes right to the floor. Could it be a bad master cylinder. Even though it’s new, could a defective unit cause this?

If the master cylinder wasn't bench bled, it could still have air in it.

The master cylinder if it’s in proper working order will not trap air it will bleed fine on the truck
The factory did not have to bench bleed before installing
There are two holes in the master to the reservoir so that airlock cannot happen
One hole is very small less than 1/16 it’s just a bit larger than a needle
With that second hole clear you won’t lock air
The designers would not have made a product that couldn’t be installed dry and bled in place
Bench bleeding is an urban myth that can damage the master if you over travel it a fraction too much
I’ve installed these dry (lubricated) on my truck and they bleed just fine by hand with two people doing it the old fashion hard way.

Over traveling the master piston too deep will damage the rubber cup and it will be wet on the piston plunger end forever and need periodic fluid cap up
Really over-travel it and you could damage the residual pressure check valve in addition to damaging the cup
-s

My first thought was residual pressure valve, either dirty, damaged, or missing᠁.presuming this is a stock single system master cylinder᠁.

If it was mine, I would replace the master cylinder. Not all that expensive.

It would be worth checking to see if the tiny hole inside of the master cylinder is not clogged with a tiny wire.
I had a brand new one which had a shiny piece of what looked like varnish plugging that hole. It just looked like a bubble of brake fluid, but the tiny wire verified that it was as hard as a carp.