The Cranes will only handle so much spring pressure and lift. They are clearanced fit to shaft..No needle bearings at shaft..Aluminium fatigue easy when riding bare against steel shafts with high spring pressure...Where Harland Sharps have needle bearings to ride on at the shaft..Also the crane units will have a clearance problem on larger diameter springs, they will hit the outside edge of the retainer on the bottom side...
poppaj