Brake question.

[70Custom10Nut]

What would cause the brakes on my truck to not release? I just replaced all 4 drums/shoes and the cylinders on the back ones (Also replaced a faulty booster). I'm thinking that one of front cylinders is sticking or not releasing. I know this is an easy fix to replace them both, but I'd just like an opinion or two before I tear it all apart. Any advice? Thanks, Cnut

[spatz]

The main thing that comes to my mind, is with drums brakes, is that they should spin freely when no pressure is applied to the peddle. When first set-up after replacement, adjustment should be to where you can hear a light whisper of a drag. anything tighter than that the brakes shoes will get hot and expand and lock up the wheel.

Also you said you replaced the booster, then check the length of
the pin in the booster against the old one, where it meets the master. if it is longer it could be applying the brakes all the times. this is just off the top of my head good luck

[68gmsee]

I'm assuming that by not releasing you mean that when you depress the padal the brake shoes will expand and stay expanded in the drum.
The primary cause of that barring booster and/or mc problems is the rubber brake lines.

They swell internally and you won't be able to see the problem. The fluid is under pressure going to the brakes but under spring tension going back. This tension may not be enough to push the fluid back and release the brakes. It happens quite frequently on these old vehicles.

A good test is to have someone step on the brakes and then loosen the bleed valve to see if that relases the tension.

[70Custom10Nut]

Thanks, I did adjust the rod length when I put the new booster in, so I know that's not it. But, the problem is that it seems as though the brakes are not releasing after being applied. That's why the front cylinders are the likely suspect. Cnut

[68gmsee]

Forgot to mention that the back on is on top of the rear axle and I would replace them all at one time to be on the safe side.

[Smallz72project]

First step I would do to diagnose...jack it up, have some one press the brakes and then walk around and spin the tires and see where the problem lies. It could be multiple things...lines, wheel cylinders, valves, and sometimes your e-brake cables. But if you can narrow it down to what tire/s are not releasing then you can go from there, once found start at the mastercylinder and work your way back, cracking the line and seeing if the pressure has been released, if its not then go to the next junction until you find a spot that will relieve the pressure. Once you find it...its the junction above the last point that bad. Ex. you crack the master and it doesnt release the pressure, then you crack the perportioning valve and it does relieve pressure the valve is whats bad. If the pressure still isnt released after you have gone through the whole system start looking for mechanical failures or hang ups (shoe hold down and return springs, e-brake cable, e-brake arm so forth).