A surgical instrument that includes a surgical end effector that is coupled to a shaft assembly by an articulation joint. A flexible firing beam extends through the articulation joint to interface with a firing member in the surgical end effector to apply a firing motion thereto. In at least one form, a pair of firing beam support members flank the flexible firing beam across the articulation joint. The firing beam support members are movably coupled together to prevent lateral movement away from each other in directions transverse to a shaft axis that is defined by the shaft assembly while permitting the firing beam support members to move axially relative to each other.
