We have determined the gravitational torque of a sample of 45 galaxies observed at K band with the 4.2m William Herschel Telescope. The results of this sample, combined with those for a sample of 30 galaxies previously analysed (Buta & Block 2001), show that the gravitational bar torque correlates only weakly with the optical bar type listed in the Revised Shapley-Ames and de Vaucouleurs systems. In fact, some classically unbarred galaxies have larger bar torques than classically barred galaxies. The Hubble classification scheme poorly recognizes the gravitational influences of the bar perturbation in the force field.