Rear brake caliper question, outer adjuster appears to be leaking, will not tighten to set clearance Options

[DRPHIL914]

my calipers were all fully restored by PMB performance around
5 years ago of so, when we did all new hard and soft lines. The whole system was replaced then, and i check and set clearance yearly. last year i had to do a new master cylinder so i did that ans set the clearance right before Werks Reunion last May.
now it’s time again and i noticed when i pulled the wheel there is a very small amount of fluid leakage around that outer adjuster, and after i loosened the lock but i turned the inter adjuster but it didn’t tighten up the pad at all it just spins! there is way too much space there and it needs to be in quite a bit.

any thoughts here? am i going to need to send this in?

@EricShea

[GregAmy]

...and the o-ring gets easily damaged if you allow the shaft to work inward as you're trying to retract the pads.

The little circlip on the thread is intended to keep that from happening, to stop the shaft from working inward, but sometimes it gets lost or damaged (or you horse the nut across it, damaging it) allowing the shaft to work inwards and the o-ring to unseat. If the circlip doesn't catch then as you screw in the shaft, instead of retracting the piston you're screwing the shaft inward...until the oiring around its shaft comes out of its seat.

The thin nut is just a locknut to keep the shaft from turning. You should not remove it entirely, defintely not across that circlip.

You might get away with re-seating the o-ring back into its bore by using a screwdriver to gently pry back the pad into the caliper as you screw in the threaded shaft. But do it slowly and carefully...otherwise the calipers have to come out.

I hate the design. but it is what is it...