Urethane Flexible coupling torsional stiffness

[jsethen]

I was wondering if there was a simple formula for caculating the torsional stiffness of a urethane section and what information might be required to complete this calculation. The part I am looking at is a flexible coupling insert. I have a data sheet on the material giving me the Tensile strength,Elongation at break, 100% Modulus, Compressive Modulus at 5%,10%,15%,20% and 25%. Hope someone can help, first time posting, not sure what to expect.

Thanks,
John