The 3-4 accumulator bore on GM 4L60 and 4L60-E series cases can become scored, resulting in the loss of 4th servo feed and 4th accumulator pressure. Scoring is caused by repeated oscillation of the accumulator piston within the bore during normal operation. Once this bore is damaged the case must be scrapped. Sonnax 3-4 accumulator sleeve kit 77998-01K conteracts bore wear and features upgraded materials for greater durability. The kit's piston is compatible with all OE accumulator springs.
Contact a Sonnax Parts Distributor.