Optimizing the Fastening Strategy & Joint Integrity to Reduce Stresses in Ring Gear Bolts on Rear Differential Assemblies

Ring gear bolts in differentials are often modified in size to accommodate the additional clamp load that is required due to an increase in torque from a vehicle's powertrain. Depending on a given program several constraints need to be considered. These include cost, validation time, reliability / durability and timing for implementation. In this paper, a Finite Element Analysis (FEA) procedure for analyzing stresses in ring gear bolts within a rear differential assembly is outlined and the computational results are then compared to quasi-static bench test results that were developed to measure bending and tension loads in the ring gear bolts during loading and unloading of the axle pinion. A dynamometer test is then developed to duplicate the failure mode and provide a comparison of the design changes proposed and the expected improvement in durability. This paper will identify alternative solutions to using larger sized (diameter, length) ring gear bolts in rear differential assemblies by optimizing the fastening strategy and the joint integrity between these two components (Ring gear and Differential).