October 26, 2017
Vehicles with Toyota/Lexus U760E and U760F transmissions may exhibit second and sixth gear shift timing concerns such as flares and bind-ups, slipping, or loss of second and sixth gear operation altogether. Burnt B1 brake clutches and loss of manual first may also result. These problems are often caused by persistent oscillation of the steel B1 apply boost valve within the aluminum boost sleeve, creating excess wear and a path for circuit pressure to exhaust, preventing proper clutch application. Installing Sonnax B1 apply boost valve kit 47740-40K re-establishes the hydraulic integrity of this circuit, restoring normal shift operation.
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.
A vacuum test at the port indicated fails to hold at least 18 in-Hg.