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-style pumps. Drop-in Zip Valve™ parts install quickly and easily. See chart above for usage details and other boost valve options.
Learn More About Zip Valve™ Drop-In Repairs

More From This Category

MANLEY Valve, Race Master, Exhaust, 30mm Head Dia, 0.274 in. Stem Dia, 4.587 Length, For Ford, Set of 8

MANLEY Valve, Race Master, Exhaust, 30mm Head Dia, 0.274 in. Stem Dia, 4.587 Length, For Ford, Set of 8

$408.60

MANLEY Valve, Race Master, Exhaust, 32.0 mm Head Dia, 6 mm Stem Dia, 94.0 mm Length, For Nissan VQ35, Set of 12

MANLEY Valve, Race Master, Exhaust, 32.0 mm Head Dia, 6 mm Stem Dia, 94.0 mm Length, For Nissan VQ35, Set of 12

$849.04

MANLEY Valve, Race Master, Exhaust, 29 mm Head Dia, 6 mm Stem Dia, 101.52 mm Length, For Mazda Miata, Each

MANLEY Valve, Race Master, Exhaust, 29 mm Head Dia, 6 mm Stem Dia, 101.52 mm Length, For Mazda Miata, Each

$49.91

MANLEY Valve, Pro Flo, Intake, 2.205 in. Head Dia, 0.3133 in. Stem Dia, 5.2 in. Length, For Chevrolet LS7, Each

MANLEY Valve, Pro Flo, Intake, 2.205 in. Head Dia, 0.3133 in. Stem Dia, 5.2 in. Length, For Chevrolet LS7, Each

$75.93

MANLEY Valve, Race Master, Intake, 2.08 in. Head Dia, 0.3415 in. Stem Dia, 5.34 in. Length, For Chevrolet SB, Each

MANLEY Valve, Race Master, Intake, 2.08 in. Head Dia, 0.3415 in. Stem Dia, 5.34 in. Length, For Chevrolet SB, Each

$47.58

MILODON Valves, Exhaust, Race, Stainless Steel, 1.625 in. Dia, +.200 Long, Small For Chevrolet, 350, 383, 400, Set of 8

MILODON Valves, Exhaust, Race, Stainless Steel, 1.625 in. Dia, +.200 Long, Small For Chevrolet, 350, 383, 400, Set of 8

$432.85