[jman4747]

The drive shaft Steel is 3/8 hex at the input bevel gear then 3/8 round through the pivot top. It includes a grove for a 3/8 retaining ring that keeps it from falling. just above that it is 8mm with 2mm keyway (same as CIM) to fit on to the Vex Pro 8mm-1/2hex adapter. Needle roller bearings sit in the top and bottom of the pivot top to support the drive shaft. The pivot top sits under a needle roller thrust bearing and has a 1in diameter extrusion that fits into a 1in id ball bearing. This part of the assembly was based off of 1640's design. The pivot top machined to a "D" profile to match a modified gear with the same profile inside. Gear is held down by a 1in id self locking retaining ring.