4L60E 4L65E 4L70E Boost Valve Early Pump .470" o-ring style Sonnax 77898E-K

4L60E 4L65E 4L70E Boost Valve Early Pump .470" o-ring style Sonnax 77898E-K

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4L60E 4L65E 4L70E Boost Valve and Sleeve 1993-2005

for early pump design 1.907" long sleeve .470" spool diameter o-ring style
Sonnax Upgrade


  • Valve
  • Sleeve
  • O-ring - 2
  • Installation Instructions

Description: Vehicles with a 4L60E, 4L65E or 4L70E transmission frequently have poor line rise, which can result in 3-4 clutch, 2-4 band failure or poor shift quality. The duty cycle of the EPC causes the boost sleeve to wear quickly. Oil entering the torque signal orifice leaks past the boost valve and exhausts at the reverse orifice, resulting in poor line rise. Reverse oil can exhaust both to the sump and back through the torque signal orifice. The outside diameter of the boost sleeve also allows some leakage through the pump body, which decreases pressure rise. Sonnax offers a number of designs. If you are not sure which one you need, give us a call and we will match the part up for you.

Parts ship daily from our distribution center.


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If you have any problems with your order, please contact us immediately to resolve your issue. We have a technician available to assist you.

This item is packaged for Wholesale Distribution


WARRANTY requests need to be accompanied with the appropriate code

as diagnosed by a professional transmission shop.

Vehicles must be professionally diagnosed for solenoid failure prior to purchase.

We cannot guarantee any one item will fix all transmission problems.

Solenoid failure is often accompanied by additional failures;

for example valve body failures, internal wear or damaged hard parts.


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