Interpolation and Bounciness

Hi, i have a ball game, similar to pinball but with topdown view, and player controlled ball. With interpolation ON the player ball, the X and Z axis movement are smooth like they should be, but Y axis bounce looks rediculously fake. With interpolation OFF, the bounciness is realistic, but the X and Z axis movement is jerky at best.

Is there a way to interpolate X and Z axis, and not interpolate the Y axis?