My right front wheel siezed up while driving a few months ago (no smoke, just bad vibration turning into horrible vibration) by the time I stopped, I couldn't turn the wheel by hand with it lifted off the ground.

I replaced the wheel cylinders, master cylinder (manual), flex hoses, cleaned up the steel lines, and checked the bearings and repacked them. I had to adjust the adjuster wheel on the bottom all the way in to get the drum back on the hub. The drum still dragged on the shoes even though the pedal went almost to the flood before I got some braking power.

So I replaced the return springs on the top of the assembly hoping that would pull the shoes back in. The wheel spins free at first, but after a short drive, has heated up to the point of dragging again.

MP brakes website says maybe too much fluid in master cylinder, but this sounds too simple. Any body have any ideas, I promised myself I wouldn't put my headers on until the darn thing will roll more than 1/2 mile!

take off the shoes. inspect closely the "rub blocks" on the backing plates where the shoes contact the plate. There are about 4 built up areas on each side of the backing plate. Over time, grooves get worn into the rub spot preventing the shoes from returning to position. I have mig welded the grooves and then filed them flat. Remember to put grease on those rub spots to help the shoes move freely against the backing plate.

Dave,
IF the problem is still there,test drive the car till the wheel locks up, then jack up the R/F and open the bleeder screw while its still locked up.If the wheel now spins free you have a hydraulic problem.If it doesn,t change you have a mechanical problem,such as what Bhawk describes.
If it is in the hydraulics since you already replaced the most likely suspects(flex hose,wheel cyl,master cyl,)I would follow the line looking for any kinks or dents in it.Next up is any metering or proportioning valve that feeds the R/F wheel.

Do you have power brakes, perhaps you don't have any head space in your master cyl to booster mounting flange. There should be a smidgen of space before the booster pushrod contacts the piston in the master cyl, if there is none, pressure builds in the brakes, usually the front, lock up, check it out.

I have a good friend back in San Antonio, had a '71 Chevelle when I visited him 10 years ago. Had the same problem with both front drums. Figured out, he didn't know what brake cleaner was, had grease from the rebuild all over the shoes. Couple cans of brake cleaner later, no problem. Check for contamination on that side, sounds like the problem to me.

Darren

thanks everybody, I'm making progress, but not fixed yet.