Sonnax 77898EK Boost Valve Kit .490" O-Ring Style for 4L60E 4L65E 4L70E

The Sonnax 77898EK Boost Valve Kit is a drop-in replacement designed to restore hydraulic integrity and prevent leakage in GM 4L60E, 4L65E, and 4L70E transmissions with early-style pumps. This kit features an increased ratio assembly with a .490" diameter EPC spool valve (compared to the factory .470") and utilizes O-ring seals for superior sealing performance.

Solves Common Transmission Problems:

• Poor line pressure rise that leads to 3-4 clutch failure
• 2-4 band failure and compromised shift quality
• Oil leakage past worn boost valve causing pressure loss
• Cross-leakage between torque signal and reverse oil circuits

Key Features:

• .490" diameter EPC spool valve provides increased boost ratio for higher line pressure
• O-ring style design prevents leakage to sump and through pump body
• Specially hard-coated boost valve resists excessive wear from EPC solenoid duty cycle
• High-quality aluminum boost sleeve engineered to resist wear
• Drop-in Zip Valve™ design installs quickly and easily without machining
• Designed for early pump design with 1.907" long sleeve

What's Included: Boost valve, boost sleeve, and O-rings required for complete installation.

Important: This kit is specifically for early-style pumps. The 4L60E, 4L65E, and 4L70E transmissions will not function properly if the wrong early versus late design assembly is installed. Verify your OE sleeve length before ordering.

This kit provides firmer shifts and improved transmission performance, making it an excellent choice for both restoration and performance applications. Compatible with GM vehicles including Chevrolet, GMC, Buick, Cadillac, Oldsmobile, and Pontiac models equipped with 4L60E transmissions from 1993-2004 (some 2005).