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

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

by Sonnax
SKU S74507TDK
$28.79 - $28.79
$28.79
$28.79 - $28.79
$28.79
Availability:
Low stock

Delivery time

You will receive your package in 2–5 business days within the contiguous U.S.

Brand: Sonnax

Manufacturer Warranty: Yes

Fitment Type: Direct Replacement

Items Included: Line Pressure Boost Valve Kit

Manufacturer Part Number: 77898E-4K

Material: Aluminum

Universal Fitment: Yes

Vintage Part: No

Performance Part: Yes

4L60-E, 4L65-E Transmission Pump

Boost Valve Kit
Part No. 77898E-4K

Early pump design, .470" dia., O-ring style with OE ratio

GM 4L60-E and 4L65-E transmissions 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 solenoid 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 boost valve kit 77898E-4K is a large OE ratio assembly that will restore hydraulic integrity and prevent leakage in units with early-design pumps. See chart above for usage details and other boost valve options.

  • Sleeve
  • O-Rings (2)
  • Valve .470", 1 Groove

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