Sonnax 77898E-16K Boost Valve Kit 4L60E 4L65E 4L70E Late pump design, .472\" dia For Sale - New and Used

4L60-E, 4L65-E, 4L70-E Transmission
Boost Valve Kit
Part No. 77898E-16K Late pump design, .472\" dia., O-ring style with OE ratio

GM 4L60-E, 4L65-E and 4L70-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-16K is a large OE ratio assembly that will restore hydraulic integrity and prevent leakage in units with late-design pumps. Drop-in Zip Valve™ parts install quickly and easily. See chart below for usage details and other boost valve options.

Contents

• Valve 4 Grooves, .472\" dia.
• Sleeve
• O-Rings (3) 1 Extra

Symptoms:

• 3-4 Clutch failure
• 2-4 Band failure
• Low line rise
• Poor shift quality

Cause: A worn boost sleeve can allow torque signal and Reverse oil cross-leakage or leakage to sump.
Correction: Sonnax drop-in boost valve kit restores hydraulic integrity and prevents leakage.

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