An engine system includes an internal combustion engine, a driven unit, and a torsional coupling between a crankshaft of the engine and a driveshaft of the driven unit. The torsional coupling includes a driven-side disc coupled to the driveshaft, and a flywheel having an engine-side disc coupled to the crankshaft. The engine-side disc has an axial thickness in a discontinuous thickness range from about 0.2 inches to about 0.3 inches, so as to flex the engine-side disc predominantly over the driven-side disc in response to the driveline deflecting loads.