[Darren69]

AFAIK there are 2 types of spring caps. Lets call them deep and shallow for arguments sake as I'm not sure of the actual dimensions off hand. As I understand it the deep ones are for the standard clutch and the shallow ones are for a slipper clutch. I'm not sure of the exact reason for this but the slipper has a different number of plates and the pressure plate does not have the raised section with teeth like the standard one does, so it can release easier I guess.