AUTOMATIC-TRANSMISSION FLUID COMPATIBILITY WITH NYLON COMPONENTS BY THERMOMECHANICAL ANALYSIS AND THERMOGRAVIMETRY

Oxidation testing during automatic transmission fluid (ATF) developmen t showed various degrees of nylon component degradation by thermal mec hanical analysis (TMA) and thermogravimetric analysis (TGA). The espec ially sensitive nylon components were the pump rotor guides and thrust washers. ATFs formulated to contain ''basic reserve'' additives (over based calcium sulfonates) were observed to inhibit nylon transmission component degradation. The inhibition is hypothesized to occur by neut ralization of acidic oxidation by-products and formation of stabilizin g chemical films on the surface of the nylon components. Nylon parts t ested with ATFs not containing ''basic reserve'' additives were suscep tible to aggressive degradation.