A variable cam timing assembly (10) and method for an internal combustion engine of a motor vehicle includes a cam phaser (22) connected between an inner camshaft (12a) and an outer camshaft (12b) of a concentric camshaft (12). A torsional drive mechanism (14) connects between the cam phaser (22) and the inner camshaft (12a) for transmitting rotational torque. The torsional drive mechanism (14) permits adjustment for perpendicularity and axial misalignment of the inner and outer camshafts (12a, 12b), while maintaining a torsionally stiff coupling between the cam phaser (22) and one of the inner and outer camshafts (12a, 12b) of the concentric camshaft (12). The torsional drive mechanism (14) can be formed from one of a flexible shaft coupling (40), a transversely split driven gear (140), a transversely split sprocket ring gear (240), a transverse face spline gear (340), and a pin and slot combination drive (440).