One embodiment of the invention includes a system for shifting a torsional mode frequency of a rotary device, the system comprising: a plurality of mass rings, each of the plurality of mass rings comprising: a pair of radially-segmented half rings; and at least one channel through each of the radially-segmented half rings, the at least one channel oriented substantially perpendicular to the radial segmentation of the mass ring, whereby the plurality of mass rings may be aligned and secured through the at least one channel of each radially-segmented half ring such that the radial segmentation of each mass ring is staggered with respect to the radial segmentation of an adjacent mass ring.