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Symptoms:
  • Delayed Reverse
  • Harsh shifts
  • High line pressure
  • Low line pressure
  • No Reverse
  • Soft shifts
Cause:

A worn boost valve sleeve allowing torque signal and/or reverse pressure to cross leak or exhaust can cause these complaints.

Correction:

This replacement boost valve assembly restores hydraulic integrity to the circuits and properly controls line rise.

4T80-E

Boost Valve Kit

Part No.

72754-01K

Boost Valve Kit
  • 72754-01k_combo

  • Boost Valve Kit

Small_72754-01k_combo Small_72754-01k

4T80-E

Boost Valve Kit

Part No. 72754-01K

  • Valve
  • Sleeve

Factory style sleeve, no o-rings

Complaint:

  • Delayed Reverse
  • Harsh shifts
  • High line pressure
  • Low line pressure
  • No Reverse
  • Soft shifts

Cause:

A worn boost valve sleeve allowing torque signal and/or reverse pressure to cross leak or exhaust can cause these complaints.


Correction:

This replacement boost valve assembly restores hydraulic integrity to the circuits and properly controls line rise.

The boost valve assembly is activated by torque signal pressure from the pressure control solenoid and reverse pressure to aid in adjusting line pressure at the pressure regulator valve. This boost valve is continuously oscillating in the sleeve, which leads to wear and hydraulic leakage. When wear occurs, critical oil pressure is allowed to cross leak between the circuits or leak to exhaust. These leaks can result in either no line rise or an unwanted increase in line pressure. Sonnax offers a replacement boost valve assembly 72754-01K that restores hydraulic integrity and properly controlled line rise. The sleeve is manufactured from highly wear resistant aluminum, and the valve from anodized aluminum. Tight tolerances on the sleeve and valve maintain an ideal fit that prevents leakage.

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