A valve assembly includes a valve housing defining a bore with a first axis extending along a length of the bore, and a valve shaft partially disposed within the bore along a second axis that is perpendicular to the first axis. The valve assembly additionally includes a valve plate coupled to the valve shaft and disposed within the bore, and a restricting device including a stop member and an engagement member. The stop member extends from the valve housing and presents a stop surface. The engagement member extends from the valve shaft and presents an engagement surface. At least one of the stop surface and the engagement surface is non-parallel with the second axis. The at least one non-parallel surface engages the other of the stop member and the engagement member and biases the valve shaft axially along the second axis.