Abstract: A blocking pin type synchronizer having a high torque to volume ratio. The synchronizer includes two synchronizer cones (42) held apart by blocking pins (40). Disposed between the cones (42) are spring assemblies (62) of novel construction, each spring assembly including a rectangular spring housing (64), a base plate (66), and a pair of opposed leaf springs (68). The housing has opposed slotted side walls (82). The base plate and the springs are each provided with tabs (92), (98) received within the slots for maintaining the base plate and springs in a centered position. The springs hold the spring housing and base plate apart. The cones are provided with recesses (88), surfaces (86) of the base plate being biased into contact with radial outer surfaces of the recesses (88) to maintain the spring assemblies from rotation.