A common condition in 4L60-E transmissions is a burned forward clutch or delayed engagement. A worn forward accumulator piston pin bore is frequently the source of this condition. The aluminum piston continuously oscillates on a hardened steel pin, which can cause wear resulting in forward clutch oil exhausting. This oil loss reduces accumulator action and decreases the forward clutch apply pressure. The Sonnax replacement oversized accumulator pin 77754-01K eliminates this problem.