o^ ^^ ^^ SOCIETY OF AUTOMOTIVE ENGINEERS, INC. 485 Lexington Avenue, New York, N. Y. 10017 The Chrysler TorqueFlite and Automatic Transmission Fluid Raymond A. Kobe and James C. Wagner Engineering Office, Chrysler Corp. SOCI OFAUTOMOTIVE ENGINEERS Automotive Engineering Congress Detroit, IVIich. January 8-12,1968 680036 Downloaded from SAE International by University of Wisconsin - Madison , Saturday, September 08, 2018680036 The Chrysler TorqueFlite and Automatic Transmission Fluid Raymond A. Kobe and James C. Wagner Engineering Office, Chrysler Corp. THE ATTITUDE of Chrysler Corp. has been to develop trans­ missions and fluids in combination such that the fluid is con­ sidered a part of the unit. Some variability, however, is recognized because of the fact that service materials will be encountered. Therefore, it is necessary to adopt a policy that will provide some tolerance for fluid variability within the range of "good quality" and that will not require special or peculiar characteristics of the fluid for satisfactory per­ formance. FLUID CONSIDERATIONS The basic requirements of fluids for Chrysler Corp. trans­ missions will not, by design, be widely different than those recognized for the materials available in the field and will be quite similar to those required for other popular trans­ missions. It does not necessarily follow, however, that fac­ tory-fill fluids will be identical or even meet all of the de­ tailed requirements of specifications by other transmission builders. Some of the specific fluid variations involved in­ clude the following: 1. Rubber compatibility might be slightly different due to selection of polymers for conditions peculiar to a specific transmission. 2. Viscosity requirements are governed by tolerances of components which are dictated by production capabilities. 3. The fluid flash point and volatility characteristics may be slightly different due to base stock selection. 4. Emphasis on the importance of particular performance characteristics of fluid for a new transmission built for com­ mon usage will not necessarily be the same as the emphasis on other characteristics of fluids for a used transmission in a specific service. 5. In most cases, the factory-fill fluid is expected to live longer than commonly available field fluid. FLUID MODIFICATION In 1963, it was decided that improvements in factory-fill fluid could be of benefit to overall vehicle performance and component life. Reviewing the properties of the factory-fill (3) automatic transmission fluids used (better described as a typical suffix A fluid), it was decided that the majority of the effort be focused on two areas. These were: 1. Low temperature viscosity reduction. 2. Improved fluid life (oxidation stability). The first of these items is of interest because the auto­ matic transmission adds a significant frictional drag load to ABSTRACT- Increasing demands on automatic transmissions due to performance considerations, higher speed driving (1)*, heav­ ier duty operation (that is, trailer towing) (2), and extended warranty life, have placed new and more stringent require- * Numbers in parentheses designate References at end of paper. ments on the transmission and fluid. The areas of increased fluid stress are oxidation stability due to higher operating temperatures, and shear stability because of higher shear rates. In meeting these needs, a transmission fluid has been developed which satisfies the specific requirements of the TorqueFlite transmisssion, as well as providing improvement in low-temperature engine starting performance. Downloaded from SAE International by University of Wisconsin - Madison , Saturday, September 08, 2018the engine during the starting sequence. Transmission fluid viscosity at low temperature has a major effect on the mag­ nitude of this load. In addition, the low-temperature fluid viscosity has a direct bearing on shift engagement time and