Clutch kits and methods for converting a stock clutch assembly and the clutch assemblies resulting therefrom. Such a method entails modifying a stock clutch assembly comprising a stock drum and stock friction and driving plates installed in an interior cavity of the drum. The method includes securing a pressure plate to the drum with threads to enclose stock or modified friction and driving plates within the interior cavity of the drum. The pressure plate can be configured to axially externally extend the interior cavity of the drum so that additional friction and/or driving plates may accommodated within the interior cavity.