February 21, 2013
Vehicles with '95-later GM 4L80-E and 4L85-E transmissions commonly exhibit wear in the Reverse checkball sleeve located in the 3-4 shift valve bore. This issue is caused by normal movement of the checkball within the sleeve over time. As wear progresses, sealing function of the checkball becomes compromised and results in loss of apply pressure to direct clutches. Consequences of this pressure loss are slipping or no 3rd and 4th Gears, burnt direct clutches and ratio codes.
Installing Sonnax 3rd and Reverse checkball sleeve kit 34200-47K restores the hydraulic integrity of this circuit to reestablish normal shift operation and performance.
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.