I have drum brakes on the front of my 71 F 100 (I know i should change to disk). Every thing is new, drums, pads, wheel cylinders, rubber brake lines, spring kit, and backing plates, yet with the truck on the lift if I roll the tires back it rolls fine if I roll in forward it gets stuck (jambs up). Both front wheels do it. I have bleed the brakes also. Can't figure this out. Thank Frank

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Have the drums been turned? Maybe catching a ridge in the inside edge? Try backing off the adjustment a little
Also are the leading edges of the brake liner material tapered down or squared off?

 

Drums are brand new so are brake pads. And I've backed off on the adjustment , still same problem. Could it be a master cylinder issue? It's really weird I have never had this problem before but this is also my first Ford.

 

Does it stick after you have applied the brake pedal? Shoes and springs look retracted in your picture.
If it’s sticking after you split pedal, try opening a bleeder while it’s stuck and see if it releases

 

After I apply the brakes (while the truck is in the air) the brakes release and wheels will spin backwards but when I spin them forward something hangs up.??

 

And it's both wheels. It has to be a hydraulic issue. Like pressure isn't releasing all the way. That's why I'm thinking master cylinder

 

That’s why I sugested opening a bleeder while it’s suck to see if it releases
Or you could open the line at the master cyl, and see if it releases
Possibly a blockage at the proportioning valve too

 

Just thinking , could the shoes be sticking on the new paint on the backing plates and not retracting?

 

Ok. If I open the bleeder and it releases what does that tell me the problem is? Master cylinder or proportioning valve?

 

No It was doing that before the new backing plates

 

I don’t believe there are any moving parts in the p valve, so I think I would take the lines off and clean it out with brake clean and air , then try the brakes again. If it’s still doing it , gotta be master cyl.
A lot of work, but less cost if it works

 

Ok sounds like a plan. I'll let you know how it turns out. Probably wont get to it until Monday. Thanks for your help.

 

Found this article. There isn't a proportioning valve on the 71 its a Brake Pressure Differential Valve and there is an $8 rebuild kit for it. The little light on the dash above the e brake handle is a warning light for that valve and mine is on.
https://www.fordification.com/tech/propvalve101.htm

 

Just something I heard on another site; Some drums are not riveted to the hub, and the replacement drums may not be centered as factory, causing a slight wobble. Try rotating the drum on it's hub by 1/5, and see if the binding is better or worse. The cure is to drill and rivet them to the hubs, If that was how the originals were, then turn them as a unit.
The differential valve should not affect braking, however it's 50 years old and could be gummed up inside, given the work you have already done, cleaning it up is a good plan.

 

The old ones weren't riveted but what you're saying makes sense. I'll try that too. Thanks