890721 Frictional Response of Automatic Transmission Fluids in Band and Disc Clutches Andrew G. Papay and Rolfe J. Hartley Ethyl Petroleum Additives. Inc. International Congress and Exposition Detroit, Michigan February 27-March 3, 1989 Downloaded from SAE International by University of British Columbia, Monday, August 20, 2018The appearance of the code at the bottom of the first page of this paper indicates SAE's consent that copies of the paper may be made for personal or internal use, or for the personal or internal use of specific clients. This consent is given on the con­ dition, however, that the copier pay the stated per article copy fee through the Copyright Clearance Center, Inc., Operations Center, P.O. Box 765, Schenectady, N.Y. 12301, for copying beyond that permitted by Sections 107 or 108 of the U.S. Copyright Law. This consent does not extend to other kinds of copying such as copying for general distribution, for advertising or promotional purposes, for creating new collective works, or for resale. Papers published prior to 1978 may also be copied at a per paper fee of $2.50 under the above stated conditions. SAE routinely stocks printed papers for a period of three years following date of publication. Direct your orders to SAE Order Department. To obtain quantity reprint rates, permission to reprint a technical paper or per­ mission to use copyrighted SAE publications in other works, contact the SAE Publications Division. No part of this publication may be reproduced in any form, in an electronic retrieval system or otherwise, without the prior written permission of the publisher. ISSN 0148-7191 Copyright © 1989 Society of Automotive Engineers, Inc. Positions and opinions advanced in this paper are those of the author(s) and not necessarily those of SAE. The author is solely responsible for the content of the paper, A process is available by which discussions will be printed with the paper if it is published in SAE Transactions. For permission to publish this paper in full or in part, contact the SAE Publications Division. Persons wishing to submit papers to be considered for presentation or publication through SAE should send the manuscript or a 300 word abstract of a proposed manus­ cript to: Secretary, Engineering Activity Board, SAE. Printed In U.S.A. Downloaded from SAE International by University of British Columbia, Monday, August 20, 2018890721 Frictional Response of Automatic Transmission Fluids in Band and Disc Clutches Andrew G. Papay and Rolfe J. Hartley Ethyl Petroleum Additives. Inc. ABSTRACT The frictional response of automatic transmission fluids (ATF) in band clutches is significantly different from that in disc clutches. A research program was undertaken to investigate these differences and to explore effects of ATF chemistry on frictional response. Two disc clutch tests (the HEFCAD and the MERCONÒ friction durability procedures), as well as two band tests (the THM 70G-R4 and the 125C) , were run on different fluids. Vehicle shift-feel tests were also run to better gauge the results. It was found that the band tests yielded high static friction relative to dynamic friction whereas the disc clutch test results frequently gave the reverse. The static- minus-dynamic value (S-D), as measured in some of these bench tests, appears to predict the shift quality of a given fluid. Fluids based on sulfur-phosphorus (S-P) chemistry seens to bridge the gap between the disc clutch and band clutch friction better than fluids based on ZDDP chemistry. The findings are believed to be helpful to the formulators of DEXRON® -III ATF's. (DEXRON®-III is a future specification intended for a new generation of ATF for GM transmissions.) PREFACE FRICTIONAL PROPERTIES are at the heart of the automatic transmission fluid function. Friction, a rather unwelcome expression of energy loss in mechanical work transfer, is used in this case for a positi