Ohtani, H., Zreik, K., Steigerwald, E., Knaffel, M. et al., "Shudder and Frictional Characteristics Evaluation of Dual Clutch Transmission Fluids," SAE Technical Paper 2014-01-1988, 2014, doi:10.4271/2014-01-1988.
Under the initiative of The United States Council for Automotive Research LLC (USCAR) , we have developed and run comprehensive friction tests of dual clutch transmission fluids (DCTFs). The focus of this study is to quantify the anti-shudder durability over a simulated oil life of 75,000 shifts. We have evaluated six DCT fluids, including 2 fluids with known field shudder performance.Six different tests were conducted using a DC motor-driven friction test machine (GK test bench): 1. Force Controlled Continuous Slip, 2. Dynamic Friction, 3. Speed controlled Acceleration-Deceleration, 4. Motor-torque controlled Acceleration-Deceleration, 5. Static Friction, and 6. Static Break-Away. The test fluids were aged (with the clutch system) on the test bench to create a realistic aging of the entire friction system simultaneously.The Force Controlled Continuous Slip mode has demonstrated a correlation with anti-shudder performance in the field, whereas other tests revealed important properties such as torque capacity and shift qualities. The study has provided an important data in order to establish anti-shudder test methods and specifications for DCT fluids.This project was undertaken and financially supported by the Transmission Working Group of USCAR.