Brake Problem

[special-K]

I have an issue with the brakes on my '71 C/30. They don't seem to be releasing at all four corners.
A little history:
I bought the truck in '06 and it had just had brakes done. I'm guessing it was just shoes and pads that he called new brakes. The truck has a cab from a C/10 and that is the booster and,I assume,master cylinder/proportioning valve it has. I have hardly driven the truck,but up and down the road a bit. The brakes have operated fine,except the pedal stays down to where if you don't pull it up the brake lights stay on. That's probably just a weak return spring. It needed a starter,then battery,then a carb rebuild due to not being started so long. Now that it's up and running the brakes seem to be sticking.
I noticed in my driveway it seemed to not want to roll. The e-brake doesn't work,so it wasn't that. Going up the road I can tell it's held back and it won't even pull 4th gear (with 5.13s). The brakes are definitely sticking. I figured maybe a caliper or both got sticky sitting. I went about a mile up the road thinking maybe they'd free up. I figured I'd see which hub was hot and tear into it. But,it's all four. I suspected the wrong booster/master cyl/prop valve,but why did it work before and what would sitting do to affect that?
Just looking for suggestions. Has anyone experienced something like this before? I suspect it's up top on the brakes since it's all four wheels at once.

[JimKshortstep4x4]

Try loosening a bleeder valve to see if it is fluid pressure causing the problem.

Jim

[Longhorn Man]

the 1/2 ton trucks and 20/30 series trucks do not share the same master. I can't remember which is wich (and I am 500 miles from my trucks at the moment) but one of them has the front reservoir feeds the front and the rear feeds the rear... and the other rucks are plumbed backwards... front feeds rear/rear feeds front. (I want to say 20 and 30 series has front reservoir to front, and 10 series rear reservoir feeds the front)
There's a chance that the pivot points for the brake pushrod could be sticking. The one on the pedal has never been a problem for me, but the one behind the booster with a clip on a rod, I've had that one get rusty and stick.
As implied above, it could be a hose problem, but I would think not likely since that would mean all three are bad at once.

[68gmsee]

re. loosening valve: You can loosen the bleed valve to see if it's hydraulic pressure or mechanical. May be rusted or sticking master cylinder but I'm going to guess that since you say all four wheels seem to stick, it's going to be a booster problem. Maybe the hub,valve rusted and not allowing free movement.

[wilbilt]

I would lean toward a sticking MC pushrod/linkage as well. Try loosening the MC to booster nuts, pull the MC forward a bit and see if the brakes release.

[71 super]

the m/c for 20/30 the front control bowl controls rear, rear bowl feeds front. As far as problem beyond I cant offer help but interested in the solution.

[Andy4639]

If you break the rear bleeder either side and it has pressure then you will know you have a MC sticking right. Then you can start looking there.
May need to change the brake fluid in the system. Moisture in the system will cause rust on the inside and may be making components to stick.

[special-K]

These are great suggestions...thanks! I sure did get lazy once I came on this site. I used to have to go out and get dirty to figure it out myself . I do believe it has to be something to do with the master cylinder and/or booster. I had never heard of a m/c freezing up from rust. This truck sits outside,but is dry inside and under the hood. I'll try releasing the pressure through the bleeder and loosening the m/c mount to move forward. Can I just put some nuts in there and get away with that? Naw,I have a master cylinder/booster from my old '71 C/20 I parted. I think what'll end up happening is I'll put that on and use the C/10 one on there now as a core for a new set-up for my '67 shortbed project. That'll eliminate the master cyl/booster as a possibility and it will get the truck together the way it should be.

[MagmaJct]

Good suggestions by others, I'd like to add that rubber lines can fail in such a way that they don't allow fluid to return to the MC. (Acting like a check valve).

[special-K]

Originally Posted by JimKshortstep4x4

Try loosening a bleeder valve to see if it is fluid pressure causing the problem.

Jim

What bleeder valve do you mean?

[68gmsee]

Originally Posted by special-K

What bleeder valve do you mean?

I believe he meant the brake cylinder bleeder valve of the wheel that's locked up.

As has been mentioned, be aware that the rubber lines can go bad and collapse internally preventing brake shoes from retracting quickly. If they're bad enough, even preventing the shoes to retract at all. And you can't tell by looking at them. Been there.

If in doubt I'd replace those anyway.

[special-K]

Oh,ok. It's the all four at once thing that makes me figure it's nothing at the wheels. If I was keeping it I'd go all through the system. My problem is I am wanting to sell it (locally) and just want it drivable. I'm not asking enough to justify getting everything tip-top.

[fastwillie 696969]

Originally Posted by special-K

What bleeder valve do you mean?

i think he meant the one inside of the booster on the vaccum side ,have you tried to diagnoise the power booster ,it may be the problem ,see the fig.1 ,the diaphram goes bad ,depending on which side it goes bad ,either it sticks or no pressure at all . pump the brake pedal up hold em to the floor ,start the truck ,see if the pedal moves at all ,if it moves its good ,if hard as a rock no movement junk it .
check hoses and lines .

[special-K]

Good info,thanks! That's what I was wondering. Now it's raining all weak and it's outside. Next question...What's the best way to build a tent?

[Andy4639]

special-K,
Next question...What's the best way to build a tent?

When it quits raining!

[68gmsee]

Rain? What's that?

[special-K]

Still no rain in Houston? Wow! I thought Lee got you all some rain for sure. Sorry to hear that. He's getting us now.

[68gmsee]

Originally Posted by special-K

Still no rain in Houston? Wow! I thought Lee got you all some rain for sure. Sorry to hear that. He's getting us now.

I'm in between Houston and Waco... 90 miles to Houston and 90 miles to Waco. Over here Lee just brought us misery. High winds causing out of control wildfires but not a drop of rain.

[special-K]

You sure didn't need that. I hope you can buy a break soon.