Technical 1961 F-100 front brakes headscratcher?

Looking for assistance from the collective HAMB brain trust on an issue my cousin is having with his 1961 F-100 unibody.
He has a re-occurring issue with his front brakes hanging up. It varies in pressure but most recently they were locked up enough he had to release the pressure from his wheel cylinder. Once he drove home it was already binding up again.
I was leaning towards the rubber lines, as everything was replaced with new including the hard lines and master/wheel cylinders...however after replacing both rubber hoses with quality new ones there's no change.
He believes it's both sides locking up but passenger side for certain as that's the one he bled (and it gets ripping hot)
No deviations from the stock system, so it's a single master etc.
Any ideas? Would this era of master have any sort of check valve that's sticking? Perhaps the new cylinders are junk?

Thanks!

 

Check for endplay on the petal if it's to tight will not let fluid come back to master cylinder

 

Inside shoes and outside shoes different sizes, and both insides on one side and vice versa?

 

Shorten the shaft into the master cylinder so the port will open and let the fluid back into it.

.bjb

 

Check the pedal travel.
Wonder if there is any piston depth difference between old and new master cyl.

 

M/C actuating rod too tight is my first thought. There needs to be about a quarter inch of pedal free play before engaging the piston. Might pull the drums off just to verify things are retracting properly and not hanging up.
Hard lines too close to high heat? Air in the lines can expand with heat and cause problems like this also.

 

Cheap, offshore drums severely out of round? Have the drums turned. It happened to me!

 

Lube the pedal assembly and make sure the pedal is returning all the way every time. My pedal was just slightly sticking and not returning completely making the brakes stayed applied. It doesn't take much. Of course, I only found this after tearing the brakes apart, adjusting the M/C rod, bleeding, and rebleeding, etc.

 

If you have adequate pedal free play, look at the front backing plates, specifically the three 'pads' behind each brake shoe that they ride on for wear. These can get grooves worn into them, and if the shoe gets into that groove it can fail to retract all the way. Welding up the grooves and then grinding them back flat is the repair...

 

I never thought about the pedal rod, I wasn't there when he replaced it so that very well could be the problem!
I'll run it past him and see what he says.

thanks fellas!

 

I second.....

 

If it's not the rod, make sure nobody but anything but brake fluid in it. It can cause the rubber to swell and cause all kinds of strange symptoms, including random lockups.