You got it DarkDan,
Vibrations (shudder or stick slip) in automatic transmissions (AT) caused by continuous slip torque converter clutches and shifting clutches are greatly reduced or eliminated by the use of special Friction-Modified fluids.
Automatic transmission fluids (ATF) are well known throughout the history of the automobile. In general however, automatic transmission suppliers and manufacturers specify performance characteristics of the transmission operating with a fluid rather than fluid composition for use in the transmission. It is then up to fluid providers to formulate fluids which meet performance characteristics. Recently, performance requirements for ATFs Service Fills have become more stringent with publication of DEXTRON-III ATF Specification by General Motors, GM 6297M, April, 1993. The Specification is available from General Motors, Material Engineering Transmissions, M/C 748 Ypsilanti, Mich 48197.
Low frequency vibration in continuous slip torque converter clutches (CSTCC) has been defined as shudder. The shudder vibration is related to stick slip friction characteristics of the engaged CSTCC rotating at slow speeds. Further, shudder has two components, initial shudder and shudder durability. The latter is shudder which develops over time.
Shuder is most prevalent during Breaking-in when the clutch surfaces are trying to flatten out.
Newly developed complex amines and other special additive chmicals make up the totality of the Friction-Modifiers in ATF fluid.
[ April 12, 2004, 02:36 PM: Message edited by: MolaKule ]