OVERSIZED PRIMARY REG & BOOST VALVE KIT
# 78790K

OVERSIZED PRIMARY REG & BOOST VALVE KIT

Tool Required

Symptoms:

  • Soft shifts
  • Low line pressure
  • Harsh shifts
  • High line pressure
  • Clutch & band failures
  • High line pressure in Reverse
  • Low converter pressure

Cause:
Continuous oscillation of the pressure regulator valve causes valve body bore wear, which results in line pressure irregularities and valve instability. Severe wear of the boost valve sleeve allows EPC and reverse oil leakage.

Correction:
Sonnax oversized pressure regulator valve and boost valve kit allows the valve body bore to be restored to normal operating condition.


Toyota/Lexus vehicles with U140E, U140F, U240E and U241E transmissions may exhibit insufficient line rise in the drive ranges, excessively high pressures in Reverse and shift issues. This may be caused by continuous oscillation of the pressure regulator valve and boost valves causing severe wear. Sonnax oversized pressure regulator and boost valve kit has upgraded materials to prevent wear and minimal clearances to restore proper hydraulic control.

  • A new spring is included to work with the oversized valve and re-establish OE regulated pressure specifications
  • Kit includes an increased ratio boost valve assembly specially designed to work with the oversized regulator valve

Content:

  • Pressure Regulator Valve
  • Pressure Regulator Spring
  • Boost Valve
  • Boost Sleeve
  • Boost Valve Plug

SONNAX Installation Instructions

Type of Product: Sundry Parts
Qty Needed:
Years:
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