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  • 1-2 Flare
  • 5-6 Flare
  • B1 brake clutches burned
  • Gear ratio codes
  • No Manual 1st
  • 2nd Slip
  • 6th Slip
  • Bind-up


Wear at B1 apply boost valve sleeve prevents proper hydraulic control of the circuit, resulting in shift timing concerns and/or burnt B1 brake clutches.


Recover hydraulic control and renew shift performance by installing Sonnax B1 apply boost valve kit.

U760E, U760F

B1 Apply Boost Valve Kit
Part No. 47740-40K

You need this if... View Instructions

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.

  • 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 for maximum life
  • 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
  • 47740 40k combo
  • 47740 40k

You need this if...

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


  • 47740 40k test