The B1 band in Aisin AW TF-80SC and TF-81SC transmissions is applied in 2nd and 6th Gears in conjunction with other clutch packs. As the B1 band control valve oscillates and strokes over time, bore deterioration results which prevents proper hydraulic control of the B1 band. This can cause flares, harsh shifts, slipping, erratic clutch apply timing, ratio codes and a burnt B1 band. Reconditioning the bore and installing Sonnax B1 band control valve kit 39741-22K restores normal shift operation and feel by re-establishing the hydraulic integrity of the B1 circuit.
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.