Ok... My sons 97 Cobra needed some new brake pads on the rear calipers... We removed them and screwed the piston back in but when we went to put the calpers back over the discs... the fit is too tight ???

I don't think it's as simple as the pistons not being screwed all the way back in or is there some other thing we missed... I don't want to even say how long it took us to screw the pistons back in ...

Also ... Is there a specail tool for doing this job or not?

Thanks in advance ...