Study of Clutch Judder Phenomenon in Manual Transmission Vehicle and Its Analysis Approach

Clutch engagement judder is a phenomenon wherein the driver experiences vibrations on seat during the clutch engagement process for the vehicle launch. Clutch engagement judder is one of the critical vehicle attributes as a part of overall vehicle NHV. Torsional oscillations, specifically originating from clutch in the driveline during clutch engagement, are referred as clutch engagement judder. Judder is a phenomenon wherein friction induced torsional vibrations are generated in the driveline because of sliding contact between clutch and flywheel, during engagement. These resulting oscillations inherit the first resonance frequency of the driveline. The engagement judder not only affects the dynamics of transmission system but also the vehicle, because of excitations being transferred to body via suspensions and mounts. Passengers experience these oscillations as vibrations during vehicle launch. If excitation level is high then it may cause discomfort to passengers. In addition to those effects, vibrations generated may cause wear of friction material and thereby reducing performance and life of clutches. In this paper, influencing factors on clutch judder, including internal factors (friction characteristic, damping) and external factors (engine torque fluctuation, applied oil pressure fluctuation, engine mount stiffness), are studied analytically. Thru a typical case study, an approach is proposed to identify the source behind clutch engagement judder on a vehicle and possible ways to eliminate or effectively minimize the engagement judder.