March 21, 2013
To help control the 3rd clutch apply pressure and shift feel in GM 4T65-E units, a 2-3 accumulator piston and an accumulator valve and sleeve that regulate fluid pressure are used. The 2-3 accumulator valve and sleeve regulate line pressure using torque signal influence and direct 2-3 accumulator pressure to the spring side of the piston, controlling the 3rd clutch apply. Wear at the sleeve or valve can allow torque signal, 2-3 accumulator or line pressures to exhaust, resulting in various 2-3 shift complaints. Some early OE valves were not anodized and are prone to significant wear and scratching.
Sonnax 2-3 accumulator valve kit 84754-53K is made to the late OE size ratio for increased torque signal influence and can be used in early valve bodies as well. Upgraded materials and design have been incorporated to prevent wear.
Vacuum testing at the port(s) indicated fails to hold the recommended minimum in-Hg, or if wear is visually detected.