The disclosure illustrates a tuned viscous torsional vibration damper having a hub member for attachment to an internal combustion engine crankshaft. An annular inertia mass is journaled within the hub member to form a working chamber which contains a viscous liquid to damp out torsional oscillations of the inertia member relative to the hub. The hub has a series of inwardly directed vanes that are received in a corresponding number of slots in the internal member to define pairs of variable chambers filled with viscous liquid. Inwardly directed blind bores in each variable chamber form gas springs which interconnect the hub and inertia member to provide tuning.