892160 Development of a New Heavy-Duty Automatic Transmission Fluid C-4 Specification F.M. de la Flor and W.E. Palmer Allison Transmission Division General Motors Corporation International Fuels and Lubricants Meeting and Exposition Baltimore, Maryland September 25-28, 1989 Downloaded from SAE International by University of New South Wales, Sunday, August 26, 2018The appearance of the ISSN code at the bottom of this page indicates SAE's consent that copies of the paper may be made for personal or internal use of specific clients. This consent is given on the condition, however, that the copier pay a $5.00 per article copy fee through the Copyright Clearance Center, Inc., Operations Center, 27 Congress St., Salem, MA 01970 for copying beyond that permitted by Sections 107or 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. SAE routinely stocks printed papers for a period of three years following date of publication. Direct your orders to SAE Customer Service Department. To obtain quantity reprint rates, permission to reprint a technical paper or permission to use copyrighted SAE publications in other works, contact the SAE Publications Group. No part of this publication may be reproduced in any form, in an electronic retrieval system or otherwise, without the prior writ­ ten 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 presen­ tation or publication through SAE should send the manuscript or a 300 word abstract of a proposed manuscript to: Secretary, Engineering Activity Board, SAE. Printed in USA Downloaded from SAE International by University of New South Wales, Sunday, August 26, 2018892160 Development of a New Heavy-Duty Automatic Transmission Fluid C-4 Specification F.M. de la Flor and W.E. Palmer Allison Transmission Division General Motors Corporation ABSTRACT Allison Transmission Division of Gen­ eral Motor Corporation has developed a new high performance heavy-duty auto­ matic transmission specification. The new Allison C-4 specification has been designed to meet higher ATD customer expectations and replace the 12-year- old Type C-3. The new C-4 specifica­ tion includes a higher temperature, more severe oxidation requirement and a new non-asbestos clutch friction test. It also incorporates a fluoroel- astomer seal compatibility test and more demanding anti-foam and anti- copper-corrosion requirements. INTRODUCTION An important element in the mainte­ nance of performance and reliability in heavy-duty automatic and powershift transmissions is the correct selection and changing of the transmission fluid. For example, figure 1 displays the oxidation life of two automatic transmission fluids (ATF) based on a laboratory test shown to correlate with failure in passenger car service (1)*. If the vehicle cooling system design results in an average tempera­ ture of 110°C, fluid "I" has the potential of providing almost five times the life of fluid "A". Of course proper vehicle design is also impor­ tant. If the vehicle system was designed to provide a temperature only (* Numbers in parentheses designate references at the end of the paper.) 10°C cooler, fluid life might be doubled. Since fluid selection is complicated by many factors such as transmission design and determination of useful fluid life and availabil­ it