nPerhaps the initial conditions that came from Rigid Dynamics that originally produced a smooth motion of the connecting rod have been ignored/discarded after you made the offset change and the connecting rod starts the dynamic simulation with zero initial velocity. The instantaneous velocity of the crank bearing excites a lateral vibration of the connecting rod as it starts the motion from rest and not with a compatible initial velocity.nTry manually creating a rotational velocity about the piston bearing as an Initial Condition for the connecting rod.n