84 Rear Brakes locking up?

[icechopper26]

Truck had problem when I bought it. Did a quality brake job, front and rear and the problem still exist. Any ideas about proportioner parts ect... before I start throwing money at the problem?

Thanks

[KimMG]

Check to see if there are any rubber lines feeding the rear brakes. Rubber brake lines break down internally and cause obstructions that can act like one-way valves.
What is a quality brake job? What did you use to clean the brake parts? Did you completely flush the hydraulics?
What kind of shoes are you using?
Are the shoes installed correctly? I have seen cars where the previous owner has installed the shoes incorrectly and the new owner just copies their mistake. The previous owner may have gotten the trailing and leading shoes mixed up.
Is there a local brake shop that does free inspections?

[Tim81ta]

I've seen this problem many times. Usually comes from internal parts for the drum brakes. Check your linkage and springs. Also, when doing you brake job, have the wheel cyclender's rebuilt.

[sassee]

I agree with tim.....I'd start with the wheel cylinders. Corrosion on the inside will cause this. If the pistons are not going all the way back in, that's the culprit. they're easy to rebuild but MAKE SURE you get a brake cylinder hone and hone out any corrosion inside the cylinder. If not, your wasting time!