Any suggestions on what to do? the RR outboard pads have zero clearance to the disc and I can't seem to make the outboard adjuster do anything - brakes seem to work fine (other than the sticking pads) - is it likely a seized piston? if so what are my options?

have already considered big hammer

help!

(stock white 74 1.8 - if I ever get technologically with it I'll post a pic)

You could remove the caliper (or at least take it off the mouting ears) and remove the pads. Then you could look at the condition of the dust boots. If they're torn then chances are that water has gotten in there and rusted the top of the piston where it goes into the bore. You "may" want to try a c-clamp to move it but generally, if you have to go to those extremes then it will need a rebuild.

Make sure the 13mm nut is loose before you attempt to turn the adjuster (had to throw that in there because I've probably seen 50 or so stripped adjusters).

thx for the advice - I'll give it a try and hope I get lucky

Let me know if I can help. Not to be pesimistic... doesn't sound good.

Are you removing the plastic cap (has a hex head on it) and using an allan wrench to adjust? Sorry if that seems real basic, but at first glance that can catch you (thinking the cap will do the adjusting.

Also, check the PP tech article
brake pad article
The adjuster screws are reverse threaded I'm pretty sure. Check that article & make sure you're turning "em correctly.

Inner Adjusters:
Clockwise = Moves the piston "Out" toward the rotor
Counter Clockwise = In

Outer Adjusters:
Clockwise = In
Counter Clockwise = Moves the piston "Out" toward the rotor

The adjuster screws are both standard thread, it's just that the inner ones work off a "gear" making the action "reverse."

There's also a rebuild thread right here in our "Classics" threads or in my "Caliper Resource Thread" (link below) as well. If you tackle the rebuild, I do "NOT" recommend pulling the handbrake arm as suggested in the PP article. 99.9% of the time it is "NOT" necessary and the kit to reinstall it properly is $50.00 (which is roughly twice the price of a good core if you do happen to have a leak there). Not panning on the PP thread "at all", it's excellent, I just don't think the economics add up for such a procedure (removing the handbrake armature) and I personally wouldn't take the arm off to simply put it back in with old seals.

My $0.02

thanks all for the advice - have managed to 'back off the outer piston with the help of a c-clamp - turns out the locknut of the adjuster had been 'welded' to the inner adjustment screw = no wonder it wouldn't adjust!

the piston is still sticky but its driveable - for now - and its a beautiful evening...