• Delayed Reverse
  • Delayed Forward
  • Soft upshifts
  • Low pressure


Wear of the boost valve sleeve allows leakage and cross leakage of the Reverse, EPC and Cutback circuits.


Sonnax dual-ratio, drop-in boost valve kit restores the hydraulic integrity of the circuits and replaces all three OE ratios.

A340E, A340F

Dual-Ratio Boost Valve Kit
Part No. 97741-01K

Fits '00-later V6 & V8, late-style, Type 3 & 4 valve bodies.

You need this if... View Instructions Find a Distributor

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.

  • Sleeve is made from high-quality aluminum for wear resistance
  • Hardcoat anodized aluminum valves combat premature wear
  • Unique priority diameter design allows for dual-ratio in one assembly
  • Additional shims allow for tuning to the third OE ratio
  • Drop-in Zip Valve™ parts install quickly and easily
Learn More About Zip Valve™ Drop-In Repairs
  • Boost Sleeve
  • Cutback Boost Valve
  • Reverse Boost Valve
  • EPC Boost Valve Small Dia. Priority
  • EPC Boost Valve Large Dia. Priority
  • Shim .032" Thick, Selective
  • Shim .015" Thick, Selective

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.

Toyota/Lexus A340, A340E/F/H Valve Body Layout

Toyota/Lexus A340, A340E/F/H Valve Body Layout

  • A340E, A340F Dual-Ratio Boost Valve Kit 97741-01K
  • A340E, A340F Dual-Ratio Boost Valve Kit 97741-01K
  • A340E, A340F Dual-Ratio Boost Valve Kit 97741-01K details

You need this if...

Vacuum testing at the port(s) indicated fails to hold the recommended minimum in-Hg, or if wear is visually detected.

A340E, A340F Dual-Ratio Boost Valve Kit Vacuum Test Locations