Friction Materials for Slip Clutch Applications

A bench test method to evaluate the friction performance for low-speed slip clutch applications such as Electronically Controlled Converter Clutch (ECCC) was developed. Several friction materials were tested against different ATFs at various slip speeds and torque levels. The apply pressure, slip torque output, and torque vibration (shudder) amplitude were monitored while the torque converter clutch was slipping. Two kinds of shudder phenomena, Green Shudder and Long-Term Shudder, were considered. The relationship between torque-speed curve slope and torque vibration amplitude is discussed. The material properties of the friction material candidates were investigated. The results suggest that the developed test method, which measures the amplitude of torque vibration, is a valuable tool for predicting anti-shudder performance. The results also indicate that the torque-speed slope does not have a direct correlation to the torque vibration. In addition, a good friction material for the low-speed slip clutch should possess certain material characteristics.