Abstract: A pin-type, double-acting synchronizer mechanism (18) with friction clutches (20,32 and 22,34), jaw clutches (24,14b and 26,16b) and self-energizing ramps. The ramps act between a shaft (12) and a shift flange (28) which is rotatable relative to the shaft and jaw clutch members (24,26). Flange (28) includes radially inwardly extending teeth (48) defining self-energizing ramps (48a,48b,48c,48d) which act against ramps (50a,50b,50c,50d) defined by a post-like portion (50) formed from shaft splines (12b). Three circumferentially spaced pins (36) include blocker shoulders for preventing asynchronous engagement of the jaw clutches and pre-energizer surfaces which each cooperate with a pre-energizer assembly (38). Friction members (20,22) of the friction clutches are slidably splined to gears to prevent relative rotation therebetween and abut surfaces (14d,16d) defined by gears (14,16) to limit axial movement away from mating friction rings (32,34), respectively.