Superior K125 Shift Correction Kit For GM TH125 TH125C 1980-1994

Superior K125 Shift Correction Valve Body Kit for GM TH125 and TH125C automatic transmissions, also known as 3T40.

Designed for 1980-1994 TH125/TH125C applications, this transmission valve body kit provides correction components for common age- and wear-related shift concerns. It is a strong choice for professional rebuilders and experienced technicians servicing the hydraulic controls of these GM transmissions.

Key benefits include support for late shifts, weak shifts, harsh downshifts, converter shudder, converter drain-back, front seal-related concerns, and premature band wear.

The kit includes a Ben Law accumulator check valve designed to promote faster band release during the shift into third gear. When used with the supplied servo return spring, it helps support proper band release and reduce the likelihood of premature band failure. A specially designed cooler-line drain-back valve helps reduce converter drainage when the vehicle is parked. The kit also provides corrections for lockup-related issues in early auxiliary valve body designs.

Fitment:
GM TH125 automatic transmission
GM TH125C automatic transmission
Also known as 3T40
Typical application range: 1980-1994

Important:
Verify the transmission model, vehicle year, and application before ordering. This kit is intended for transmission rebuilding and valve body service. Professional installation is recommended. Use the specified ATF for the transmission application, and Lubegard ATF Protectant may be used as part of a complete transmission-fluid service.