4L60E 4L65E 4R70E FORWARD ACCUMULATOR PISTON IN VALVE BODY NUMBER A74741G 1993-2015.
4L60E Forward Accumulator. This 4L60E / 4L65E accumulator piston goes in the valve body and cushions the shock when shifting from reverse to drive. In 4L60-E units it is common for the plastic forward accumulator piston to wear or crack. This causes a fluid loss resulting is delayed engagement, slips, burned clutches and / or band. Repeated reciprocation of the accumulator piston causes the piston pin bore to wear. Fluid loss through the piston pin bore or cracks causes forward clutch to slip. The stock accumulator piston can develop a large pressure leak at the pin area over a period of 50 to 100 thousand miles.