In a transmission inertia brake a ball ramp mechanism is used to load a clutch pack to slow a rotating transmission shaft where the clutch pack is carried on a one piece drive assembly having a gear section for meshing with a transmission gear, an extension section for engaging a thrust plate in an isolator assembly, a clutch section for engaging plurality of driven clutch plates in the clutch pack and a bearing section for rotational support within a brake housing. An armature having an angled peripheral surface engages a mating friction surface formed in an end plate to form a core clutch, the armature being magnetically pulled upon energization of an electrical coil energized by a power signal from a control unit supplied through a sealed electrical connector thereby introducing a frictional braking force on the armature to activate the ball ramp mechanism. The armature is nonrotatably connected to the control ring of the ball ramp mechanism through at least one connecting pin. A Belleville spring is used to apply an axial load on the ball ramp mechanism and to drive the star in a gerotor oil pump which interacts with a ring to pump cooling lubricant throughout the clutch pack in the ball ramp mechanism.