Pinless Forward Accumulator Piston Kit

The Sonnax 77987-01K pinless forward accumulator piston kit is engineered to resolve prevalent issues within GM 4L60-E, 4L65-E, and 4L70-E transmissions. It directly addresses problems stemming from the wear or cracking of the stock plastic forward accumulator piston, which often results in fluid loss, delayed engagement, slippage, and burnt clutches or bands. This wear can also manifest as the piston pin bore wearing out, or fluid escaping through cracks in the piston, leading to a slipping forward clutch. This kit features a pinless design that eliminates the possibility of leakage through the pin bore. Additionally, the extended length of the piston helps to stabilize it and prevent it from cocking. The kit also includes steel balls for plugging the existing pin bore in the valve body. For GM 200-4R, 4L60, and 4L60-series units experiencing poor shift quality or burnt bands/clutches due to accumulator piston wear, Sonnax offers the 77998-03K pinless accumulator piston kit for the 1-2 or 3-4 accumulator bores. This kit shares the same benefits of eliminating pin bore leakage and stabilizing the piston.