Methodology for optimizing the bench testing of Steering I shaft using vehicle level data to reduce overall product development time and cost.

Steering I-shaft with rubber coupling (or hardy disc) is an important part of complete steering system mainly in body on frame vehicles. Hardy discs are used to dampen the vibrations that transmit to steering wheel through frame, steering gear and I-shaft. They also support to accommodate the variation between frame and BIW of body on frame vehicles. They are made up of rubber or other polymer composites, which have less torsional stiffness as compared to metals. The overall torsional stiffness of steering system reduces since the hardy disc is used in series in steering system, that impacts on the overall performance of steering system. So, during development I shafts with different design, stiffness of hardy discs are used to optimize the steering and NVH performance of vehicle. Considering the development time and cost, each design of I-shaft cannot be validated at vehicle level. The torsional and axial force or displacement of hardy disc is measured at vehicle level on different test tracks and block cycles are made that consists of different displacement / force along with frequencies. These block cycles are then used at bench level testing of I-shafts. This paper summarizes the methodologies to measure the force or displacement of I- shaft, converting raw data to useful block cycles and test set up for bench testing of steering I-shaft.