megane 2003 rear brakes how do you move the pistons back on the calipers?

you need a brake piston winding tool to rewind the piston back far enough to then get the new pads in place. Failing that you can try to use anything you can to wind back the piston once the old pads are removed but they will move backwards when screwing them in useing forse in the two holes located in the piston crown just try to find a suitable tool ie spanner circlip pliers to fit the two holes either side so as you can apply equal pressure tp move them inwards hope this helps you out

Marty (renault technician) england
March 2011