Sonnax 34994-02K 1-2 & 2-3 Shift Valve Spring Kit for GM 4L80E 4L85E

The Sonnax 34994-02K shift valve spring kit replaces the original 1-2 shift valve spring and 2-3 shift valve spring in GM 4L80E and 4L85E automatic transmissions. This kit addresses common shifting issues including complaints of 2nd gear starts, neutral after 2-3 shift, or no 4th gear operation.

What's Included:

• 1-2 Shift Valve Spring
• 2-3 Shift Valve Spring

Key Features:

• Springs must be used together for proper transmission operation
• Addresses shift valve float and stalling issues
• Helps maintain proper hydraulic pressure in 4th gear
• Direct replacement for worn or weak OEM springs

In 4th gear, signal A oil force must overpower the 1-2 shift valve spring and opposing signal B pressure to maintain proper gear engagement. When the original springs weaken over time, the 1-2 valve can stall or float when AFL oil drops and signal A becomes less than 58 psi, resulting in erratic shifting behavior. This kit is not a fix for leaking solenoids or leaking seals in the solenoid signal or actuator feed limit circuits—those issues must be addressed separately.

This Sonnax spring kit is designed for professional transmission rebuilders and restores proper shift valve operation in GM 4L80E and 4L85E transmissions found in trucks, SUVs, and performance vehicles.