Rotational Resonant Frequency

I need to predict the Rotational Resonant Frequency of around diskmounted to a shaft.
Setup for Natural Resonant Frequency is straight forward andIdon't have any problems. I have tried fully restraining theshaftand restraining the disk in every direction except rotational.

The results are many times lower then I would expect. Am Isettingup the model correctly, or is there a better way?SolidworksSimulation