A power turbine rotor assembly including a rotor shaft. The assembly also includes a rotor stack surrounding the rotor shaft. The assembly further includes a nut axially retaining the rotor stack. The assembly yet further includes a Vernier ring engaged with the nut and the rotor shaft, the Vernier ring having an inner ring, a plurality of inner tabs extending radially inward from the inner ring, and a plurality of outer tabs extending radially outward from the inner ring, the Vernier ring formed of at least two ring segments.