| abstract |
An effective way is described for overcoming the shudder problem associated with continuous slip torque converter clutches for use in automatic transmissions, especially shudder which occurs with new friction materials before break-in. To do this, an ATF is used in which the friction modifier system consists essentially of (i) an N-aliphatic hydrocarbyl-substituted diethanolamine in which the N-aliphatic hydrocarbyl-substituent is at least one straight chain aliphatic hydrocarbyl group free of acetylenic unsaturation and having in the range of 14 to 20 carbon atoms, and (ii) an N-aliphatic hydrocarbyl-substituted trimethylenediamine in which the N-aliphatic hydrocarbyl-substituent is at least one straight chain aliphatic hydrocarbyl group free of acetylenic unsaturation and having in the range of about 14 to about 20 carbon atoms. The ATF is devoid of any tertiary amine friction modifier component and any C12-36 aliphatic hydrocarbyl succinimide or succinamide friction modifier. Specified relative proportions and concentrations of (i) to (ii) are used. |