Rear brake piston

Hi all I'm just restoring a Williams 2 which we have had in our family from new. I'm just trying to change the rear discs and pads and I can't move the piston at all Iv turned the end with a screw driver loads but it doesn't seem to compress. Anybody had this problem before?? I am right in thinking it needs to be turned? Thanks in advance for any advice Dan

Yes it needs to be turned as well as pressed in at the same time, you need a proper brake winding tool to do it easily

Thank you for your quick response I'll give it another go tomorrow, I take it you turn it clockwise? Also what's the torque setting for the nut that holds the disc on cheers Dan