The assembly comprises a driving element (17) and an output element (20) which are elastically coupled by a torsion spring (21). The radial outward movement of the spring is restricted by a limiting element (19) and one end of the spring is held by a receiver (31,32) whose spherical surface contacts the limiting element. This surface may be produced on a locally lubricated ball (30) and the receiver may be recessed (33) so as to hold the ball opposite the limiting element. The driving element may be the piston of a torque converter transfer system, whereas the output element may be a converter turbine wheel.
