January 16, 2014
In Toyota/Lexus A340E and A340F late-style units the OE steel Reverse, EPC and cutback boost valves wear the inside diameters of the cast aluminum boost sleeve due to continuous reciprocation as they provide biasing force to adjust main line pressure. This wear allows critical Reverse, EPC and cutback fluid pressures to leak or cross-leak, creating numerous drivability complaints and part failures.
Replacing the OE assembly requires matching the correct valve spool ratio (three-dot, two-dot or no-dot sleeve) to ensure proper line pressure. The Sonnax dual-ratio boost valve kit 97741-01K not only restores hydraulic integrity, but also provides for all OE ratios in one assembly. By selecting either the large diameter priority or small diameter priority EPC boost valve and adding optional shims to the OE pressure regulator valve spring face, all three of the OE ratios can be achieved with the one assembly.
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.