Detergent and Friction Modifier Effects on Metal/Metal and Clutch Material/Metal Frictional Performance

The goal of this work was to find combinations of detergent and friction modifier additives that would produce high metal/metal friction with good clutch material performance. A baseline formulation was used with various combinations of five different detergents with five different friction modifiers. Two bench tests were used to assess performance. A CVT (Continuously Variable Transmission) Element-on-Ring Test was used to study metal/metal performance, and a VSFT (Variable Speed Friction Tester) procedure with cellulose based friction material was used to evaluate the μ-v (friction coefficient-velocity) clutch performance. Interestingly, a 400 TBN magnesium sulfonate detergent combined with a phosphorus containing friction modifier showed a special synergy. The metal/metal, element-on-ring data showed one of the highest average friction coefficients, and the VSFT results showed that this combination also displayed a moderately high dynamic friction coefficient with a high, positive μ-v slope. The positive slope is indicative of good clutch material antishudder performance. Even after prestressing (fluid aging), this combination was one of the few formulations that maintained a moderately high positive slope with a moderate dynamic coefficient of friction over the entire range of temperatures studied. In conclusion, this paper documents the full bench test results of all the different detergent and friction modifier combinations.