Sonnax Pinless Accumulator Kit for 1993 - UP GM 4L60E Transmissions. In listed GM units it is common to have poor shift quality, burnt bands or clutches due to accumulator piston wear. Repeated reciprocation of the accumulator piston causes wear at the piston pin bore interface. After this wear reaches a critical point, fluid loss through the piston pin bore cannot be compensated due to lack of pump volume. In addition, the piston can get cocked and gall the accumulator bore due to the pin bore wear or the spring bottoming out. To prevent these conditions in the 1-2 or 3-4 accumulator bores, Contents D-Ring Viton X 3 Pinless Accumulator Piston Aluminum 1-2 Pinless Accumulator Piston Aluminum 3-4 Pinless Accumulator Piston Aluminum FWD Seal PTFE X 3 Steel Ball X 6