Disk drive head stack assembly having a tapered pivot bearing

A disk drive head stack assembly of a configuration that facilitates the assembly thereof is disclosed. One or more head/arm assemblies are mounted on a pivot bearing. This pivot bearing includes a tapered section. Each head/arm assembly may be mounted on the pivot bearing. Thereafter, a retainer ring may be advanced relative to the pivot bearing. Advancement of the retainer ring along the tapered section expands the retainer ring so that the same may be disposed within a retainer ring slot of the pivot bearing. Each head/arm assembly is maintained between this retainer ring and a flange of the pivot bearing.