I've been having problems with my rear brakes (stock '74 /4). The passenger side brake was always dragging. Turns out the inside venting adjustment was jamming the pad against the rotor. Somewhat of an easy fix, although the adjustment cover hex hole had been stripped at some point.

The driver side brake was not braking (I could spin the wheel manually with the brake applied). I got the pistons unstuck by taking out the pads and letting the pistons extend a bit, then pushing them back in and replacing the pads. So now I have braking on that side, but the pads aren't releasing very well (I can't turn the rotor manually after I apply the brakes, but I can push the pads back with a screwdriver). Note that I don't have any anti-rattle springs on the calipers, removed by the PO I assume.

Will this get any better when I start driving the car (it's not certified yet, so I can't drive it on public roads)? If not, is there some kind of temporary fix that I can do without a complete rebuild? I read somewhere that you could possibly take off the calipers, extend the pistons out (but not all the way out) and clean them.

Please note that I do have my PMB rebuild kit order ready to go, but I would rather wait until the winter to do the complete rebuild.

its a fairly easy rebuild.
you can pull them one evening
and have the car back on the road the next evening...

I am sure others can! It will be much more involved process for me, haha.

Some of your symptoms sound like the flex lines are getting plugged.

Replace those while you are taking the calipers off.

I agree...deteriorated rubber lines are bad...and cheap and easy to replace.

If you find the issue is indeed the rear piston and not the flexible lines, contact Eric Shea at PMB for a set of restored calipers. They look and perform awesomely and his support is top notch.

If you were able to move the pistons back any more than a few thousandths without turning the adjusters while you pushed, you have serious internal caliper problems. If you have little or no braking on one side, the hose on that side isn't likely to be the problem. While dragging brakes are often the result of internal hose failure, the immense pressure supplied by the master cylinder usually pushes fluid through, but the near absence of pressure from the caliper won't force the fluid to return. Not a bad thing to replace those OE hoses every 20 years or so anyway, unless you're sure the system has been flushed every couple of years. Use the OE type rubber hoses and good quality DOT 4 brake fluid from a newly opened can. Ate is good, as is Castrol LMA. Avoid "racing" brake fluid for street use, as it commonly is more hygroscopic and requires more frequent replacement.

The Cap'n