Mechanical gearbox for motor vehicles

Mechanical gearbox (1) for a motor vehicle comprises: a first shaft (5); a second shaft (6); a plurality of gear pairs; a plurality of synchronizers (9); and an actuation system (10) for displacing each synchronizer (9); wherein gear pairs of two consecutive speeds are arranged so as to be engaged by two different synchronizers (9); and the actuation system (10) comprises: a third shaft (16) supporting forks (11); a plurality of circumferential cams (21) obtained on the external surface (20) of the third shaft (16); a plurality of followers (22); and a motor device (19) adapted to turn the third shaft (16); wherein the third shaft (16) is split into two halves (16a,16b), which are connected together by means of an elastic element (23) and each of which supports a part of the forks (11).