JSAE 20077048 SAE 2007-01-1974 TEST METHODS FOR DETERMINING ANTI-SHUDDER DURABILITY OF AUTOMATIC TRANSMISSION FLUIDS Joe Noles, Raymond F. Watts, Masahiro Ishikawa, Hirokazu Saito Infineum USA LP, 1900 East Linden Avenue, Linden, New Jersey 07036, USA Copyright © 2007 Society of Automotive Engineers of Japan, Inc. and Copyright © 2007 SAE International ABSTRACT Anti-shudder characteristics are an important part of automatic transmission fluid (ATF) performance. Anti- shudder performance has two aspects, initial friction aimed at the prevention of “green shudder” and anti- shudder durability which is the prevention of shudder at high vehicle mileage. Different methods of measuring anti-shudder durability give different results. We have found that some fluids give very acceptable performance when measured in a Low Velocity Friction Apparatus (LVFA) test, such as a JASO M349-2001 [1] , do not give good results when measured in a method that includes high energy engagements and oxidation. This apparent anomaly in test results is due to unexpected behavior of certain fluids after oxidation. The observation is a cause for concern relative to the widely accepted JASO method. INTRODUCTION There are currently two approaches to measuring anti-shudder durability of ATFs, one employing LVFA machines [2, 3] and one using modified SAE No.2 machines [4, 5]. The most widely accepted method employing the LVFA machine is the JASO procedure M349-2001. While both methods yield similar rankings of fluids their approach to aging the fluid is different. Our investigation was aimed at determining if the different conditions that test fluids are subjected to in these tests can cause them to give different results. Mechanisms of ATF Degradation In an operating transmission there are a number of processes that degrade the fluid. Some are mechanical, e.g. shearing, and some are chemical, e.g. oxidation. To best simulate the degradation of the fluid in the transmission as many of the degradation mechanisms as possible should be included in any bench screening test.The processes that are most responsible for degradation of the fluid are: Mechanical shearing Bulk oil oxidation with aeration in the presence of catalytic metals Thermal degradation from shifting clutches Degradation from continuous sliding in the torque converter clutch The JASO M349 test procedure which is run in an LVFA addresses only degradation from continuous sliding in the torque converter clutch. While this is a key degradation mechanism, the role of oxidation is minimized since the only oxygen available is what diffuses into the oil through the oil-air interface and there is no thermal degradation from shifting clutches. The test conditions for the JASO M349-2001 procedure are given in Table 1. Table 1. JASO M349-2001 Test Conditions PHASE PARAMETER Break-in Slipping Dynamic Mu vs V Temperature, C Reservoir -- -- -- -- Test Head 80 120 -- 40,80,120 Apply Pressure, kg/cm210 10 -- 10 Aeration Rate, cc/min -- -- -- -- RPM 100 150 -- 0-250 An SAE No. 2 machine test that we developed incorporates all of the ATF degradation processes listed above[4]. A standard SAE No. 2 machine was modified as shown in Figure 1. A variable speed drive was added to the machine and coupled to the main shaft with a one-way clutch to allow the machine to be driven with either a low speed drive or the high speed motor. A small (approximately half liter) heated fluid reservoir containing a copper coupon was added to -228-Downloaded from SAE International by Stony Brook Univ, Sunday, August 12, 2018the machine. A pump is used to circulate the test fluid from the reservoir to the test head and back. Air is introduced into the test head through a sintered metal diffuser to accelerate the oxidation of the fluid. A test cycle was developed to incorporate the fluid degradation mechanisms encountered in an automatic transmission. We believe that the role of oxidation is an important part of the aging process in a tr