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 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 for usage details and other boost valve options.
Learn More About Zip Valve™ Drop-In Repairs

More From This Category

Crow Cams SHIM 1.640" x .640" x .030"

Crow Cams SHIM 1.640" x .640" x .030"

$3.11

COMP Cams Valve Lock, Stamped, Hardened Steel, 7 Degree, 11/32 in. Valve Stem, 4 Groove, For Ford 351C, Pair

COMP Cams Valve Lock, Stamped, Hardened Steel, 7 Degree, 11/32 in. Valve Stem, 4 Groove, For Ford 351C, Pair

$2.48

MANLEY Valve Spring, Street Master, Chrome Silicon, 1.437 in. OD, 391 lbs./in. Rate, 1.085 in. Coil Bind Height, Dual, Each

MANLEY Valve Spring, Street Master, Chrome Silicon, 1.437 in. OD, 391 lbs./in. Rate, 1.085 in. Coil Bind Height, Dual, Each

$29.18

COMP Cams Steel Retainer, Tool, 7 Degree, 7mm Valve 26056 Spring, Set of 16

COMP Cams Steel Retainer, Tool, 7 Degree, 7mm Valve 26056 Spring, Set of 16

$495.54

COMP Cams Engine Valve Spring Seat, ID Spring Locator, 1.565 in. OD, .535 in. ID, .100 in. Thick, Set of 16

COMP Cams Engine Valve Spring Seat, ID Spring Locator, 1.565 in. OD, .535 in. ID, .100 in. Thick, Set of 16

$123.15

Sonnax Pressure Regulator Cushion Spring, Saturn Taat, Each

Sonnax Pressure Regulator Cushion Spring, Saturn Taat, Each

$10.50