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A project was conducted where different types of greases with different additives were evaluated in an effort to determine if performance improvements could be obtained in the universal joint application. A typical universal joint is displayed in Figure 1. Several different types of greases, calcium, lithium, lithium complex and polyurea were evaluated and compared to the current universal joint grease. The required grease for a universal joint must be a maintenance free grease that is used in a full complement of needle bearings. The results showed that a particular lithium complex grease provided the best results as seen during bench top and environmental wear testing. Customer vehicle testing of the lithium complex grease confirmed that the universal joint life was significantly improved. The new grease was subsequently placed into production use.

The effect of a different type of microalloy material on the durability and processing of an existing pitman arm design was evaluated. The durability properties of a particular type microalloy material i.e. impact toughness, impact ductility, programmed fatigue life and high load fatigue life properties, were evaluated and compared to the current production conventional heat treated material. Metallurgical evaluation was performed and showed that the hardness and microstructure of the acicular ferrite - bainitic microalloy was nearly independent of the cooling rate from hot forging and could provide equivalent or better properties as compared to conventional quench and tempered forgings.

The effects of different shot peening parameters on the fatigue life of rear axle hypoid pinion gears were evaluated. Shot hardness, shot size, intensity, shot velocity and prior heat treatment were studied and compared to current production. Metallurgical analysis of the carburized SAE 4320 gears along with residual stress gradient analysis at tooth root fillets were performed. The results showed that significant fatigue life enhancement can be achieved by precision shot peening (directed, air nozzle type) and proper determination and tight tolerance of shot peening process parameters and heat treatment.