Integrating Test and Analytical Methods for the Quantification and Identification of Manual Transmission Driveline Clunk 2001-01-1502

Driveline clunk is a phenomenon that can adversely affect customer perception of vehicle quality. Clunk is created by the impact of two driveline components as they oscillate in response to a torque disturbance in the driveline system. This disturbance is typically initiated by a driver controlled engine torque variation, most severely through a throttle or clutch manipulation. This torque variation excites a torsional response from the driveline, manifested by a variety of mechanisms such as resonances of various shafts, housings and axles, clutch oscillations, and gear impacts. Because automotive drivelines are complex systems composed of many rotating components, difficulty arises in identifying the impacts that cause clunk and evaluating the significant parameters that can positively affect these collisions.

This paper will describe the application of analysis and test methods in the investigation of clunk in a rear wheel drive, manual transmission vehicle. The interaction between analysis and test methods to design appropriate tests to isolate the primary driveline vibration from the noise response of system components and key driveline component features will be discussed. A lumped mass, transient model has been constructed to assist in the identification of the key parameters and root cause for driveline clunk. This model, limited only to the rotational properties of the driveline, analyzed the rotational dynamics of internal components of driveline subsystems during the clunk event. The tests completed during the investigation focused on rotational dynamics during the clunk response and also comprehended the noise response aspects of the phenomenon. Test methods consisting of vehicle acceleration, component shaft speed, and coincident noise measurements used to correlate and overcome model limitations will be discussed.