The invention relates to a vane-type motor cam phaser with a rotor and a camshaft. Between this rotor and the camshaft, a friction disc is braced axially by means of a central screw. Accordingly, this friction disc transmits a drive torque in a frictionally engaged manner. For pivoting the rotor in two oppositely lying directions of rotation, at least two oil channels (A, B) run through the camshaft and a hub of the rotor. At least the one oil channel (A or B) is sealed hydraulically radially inward by an inner ring part of the friction disc and radially outward by an outer ring part of the friction disc. The inner ring part and the outer ring part are joined to each other by means of a crossarm.