Rear brakes how do self adjusters work?

[Bill_H]

Hi all, Chimaera 4.0ltr 1996, getting ready for MOT so stripped cleaned and checked all the braking system. To be honest Im surprised at how good it is and everything seems to work OK.
My question....
reassembling the rear calipers and pads I rotated the caliper piston 90 degrees each direction to ensure they're not seized, (good tip on PHeads about slackening the bleed nipple), on reassembly I can see that there is a small 'nipple' on the back of the pads that fits into the slots on the caliper..... so how does the self adjuster work? The caliper cannot rotate because the nipple effectively locks it in position.
Im starting to wonder if the wrong pads were fitted some while ago.

Any advice gratefully received.

[Pink_Floyd]

Bill_H said:

Im starting to wonder if the wrong pads were fitted some while ago.
Any advice gratefully received.

Correct pads fitted. The internal mechanism sort of ratchets up as the piston comes out. The ratchet paw is on a threaded bar so when you rotate the piston it screws back in.

[spend]

When the pad has worn enough so there is clearance for the adjuster to click on 90 degs, it ratchets on the thread, then meshes until there is another clearance for it to click again IYSWIM.

I guess that was the nub of your question?