Sonnax 77898E-16K Boost Valve Kit 4L60E 4L65E 4L70E Late pump design, .472" dia

OE Spec or Performance/Custom: Performance/Custom Brand: Sonnax Interchange Part Number: S74507THK Manufacturer Warranty: No Warranty Items Included: Line Pressure Boost Valve Kit Manufacturer Part Number: 77898E-16K Country/Region of Manufacture: United States Universal Fitment: Yes Vintage Part: No Performance Part: Yes 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 decreas