Thanks! 
So I just gave the rotator a Physics Constraint Component, and set up some nodes to attach it to the hit object via the physics constraint, then it would rotate freely. Then set up a physics constraint on the tire and made it attach to the rotator the same way. Now I have a working vehicle building system! All that is left is to make a way for the blocks to snap to the vehicle’s grid and attach to the vehicle instead of the world.