AM-93-06 THE NEXT ATF CHALLENGE - MEETING FUEL EFFICIENCY NEEDS AND PROVIDING DRIVER SATISFACTION

Description:

The growing use of continuously slipping torque converter clutches provides substantial fuel economy benefits, compared to the full lock-up design, in EPA city drive cycles. However, these clutches can also produce unacceptable vibration or “shudder” if the friction characteristics of the automatic transmission fluid (ATF) are not properly matched to the friction material. Presently, no standardized tests or specifications exist to determine the fluid attributes necessary to avoid shudder. This paper considers how these performance needs will influence the ATF market over the next few years. It includes an outline of a test method developed to characterize an ATF’s shudder resistance by evaluating low-speed friction data. Also outlined are the results of a field survey of various ATFs commercially available in North America.