conically shaped drums 32 an initial resistance to free differentiation is established in the differential mechanism which resistance is increased by the axial forces applied to the clutch members by the side gears upon increased application of torque to the mechanism casing as was indicated the initial preload of the clutch members 26 is provided by the biasing mechanism 28 the biasing mechanism 28 includes a pair of spaced apart plates 70 fig3 and 4 between which are disposed a plurality of compression coil springs 72 the plates 70 include transverse walls 74 which are in abutting contact with the faces 42 of the side gears 40 and transfer the axial load of the springs 72 which are in a compressed condition to the clutch members 52 through the side gears 40 each plate 70 includes an aperture 76 formed in the transverse wall 74 and having a circular portion 78 in alignment with the recess 44 in each side gear fig5 as may be noted each plate 70 is identical to and is adapted to mate with an opposed plate thus each inwardly directed wall 80 and 82 overlaps an inwardly directed wall 80 and 82 of the other plate so that the circular portion 78 of each aperture 76 is a semi circle and together the circular portion 78 define a complete circle the aperture 76 is extended tangentially to the side wall 80 so that an upper portion of the side wall 82 on the other plate 70 may be received therein further it may be noted that the side wall 82 is located closer to the longitudinal axis a of the plate 70.