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  • B1 Clutch burned
  • C3 Clutch burned
  • Delayed Reverse
  • Low line rise in Reverse
  • Low Reverse boost
  • No Reverse
  • B4 Clutch burned
  • Reverse slip


Persistent oscillation of OE steel boost valve within aluminum sleeve results in sleeve bore wear and loss of proper Reverse pressure.


Recover hydraulic control and renew Reverse performance by installing Sonnax reverse boost valve kit.

U760E, U760F

Reverse Boost Valve Kit
Part No. 47740-38K

You need this if... View Instructions

Vehicles with Toyota/Lexus U760E and U760F transmissions may exhibit insufficient line rise in Reverse, delayed or slipping Reverse, and/or burned C3, B1, and B4 clutches. Continuous oscillation of OE steel boost valve within aluminum boost sleeve causes premature wear, creating a path for boost pressure to exhaust. Installing improved material Sonnax reverse boost valve kit 47740-38K restores the hydraulic integrity of the boost circuit to recover normal Reverse operation.

  • Restores proper line rise
  • Annular grooves help center valve in bore to reduce future side-load wear
  • Hardcoat anodized aluminum valve combats premature wear
  • Sleeve manufactured from highly wear-resistant aluminum to prevent excess wear and leakage
  • Valve
  • Sleeve

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 U660E/F, U760E/F Valve Body Layout

U660ef vbl thumb

September 30, 2005

Anatomy of a Transmission: Oil Flow in the Pump-PR-Converter-Cooler Lube Circuits

Gregg Nader

Topics: Diagnostics And Theory Transmission

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  • 47740 38k combo
  • 47740 38k

You need this if...

A vacuum test at the port indicated fails to hold at least 18 in-Hg.

  • 47740 38k test