The Disk Friction Clutch block requires only a single pressure signal to modulate the kinetic friction. You fix all its other characteristics before starting simulation.
Modeling a friction clutch at a fundamental level requires direct control over the kinetic and static friction torques. The Fundamental Friction Clutch block gives you that control. With this block, you must specify, by either external signals or internal dynamics, the kinetic friction and static friction limits (positive and negative) of the clutch as functions of time.