Sonnax 77898E-3K 4L60E Transmission Boost Valve & Sleeve Kit (.490" Diameter)

Brand: SonnaxOther Part Number: S74507FBInterchange Part Number: S74507TFKItems Included: Line Pressure Boost Valve KitManufacturer Part Number: 77898E-3KUniversal Fitment: YesVintage Part: NoPerformance Part: Yes 4L60-E, 4L65-E Transmission Boost Valve KitPart No. 77898E-3K Early pump design, .490" dia., factory style with increased 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-3K is an increased ratio assem