March 21, 2013
In GM 4T60, 4T60-E and 4T65-E units, the continuous stroking of the 1-2 (Forward) and Reverse servo boost valves wear away at the valve bore, creating excess clearance and reduced apply pressures. This can lead to 1-2 band slippage, delayed engagements, 1-2 shift flares, and decreased Reverse pressure. Sonnax oversized 1-2 and Reverse servo boost valve kit 84754-40K that will restore the hydraulic integrity and more than doubles the valve-to-bore contact area to prevent leakage.
This kit only contains one valve. If both bores need to be repaired, two kits are required.
Sonnax valve body layouts provide a detailed overview of individual units making it quick and easy to determine what’s available for the specific valve body you’re working on. See all Sonnax valve body layouts.
Vacuum testing at the port(s) indicated fails to hold the recommended minimum in-Hg, or if wear is visually detected.