Actually, Carrara no longer uses the Havok physics engine. Something to do with licensing. Not sure what version of Carrara physics got replaced. But the current physics engine was written from scratch. That said. I'm not sure I completely understand what you mean wellspunweb by a t-bone situation. But the physics engine in Carrara does have limits. Its difficult to get an animation like vehicles rolling on the ground, you'll tend to get bouncing or as you said rolling. Is there a reason you are using physics? A specific result you are looking for? Brian