Lockup Upgrade Kit
Fits 1995-15 4L60E, 4L65E, 4L70E GM SRTA units with TCC Isolator valve lands that measure .472" except hybrids Transmission Removal Not Required

SKU: 4L6-ISO-3 Category:
  1. Distributor Part Numbers
    TransGo 4L6-ISO-3
    A & Reds K61912
    Capital Core A74741Q-1
    MST 77925
    Natpro K51887EA
    OTS K77925
    PDQ TG-4L6-ISO-3
    PNH TG74741CK
    PTW K51887EA
    Summit NA
    Transtar T74741CK
    WIT A74741Q-1
  2. Documents
  3. General Details
    Oversize TCC Lock-up Isolator Valves for GM SERTA

    1995 to 2015 General Motors vehicles equipped with a 4L60E, 4L65E and 4L70E SERTA (Service Replacement Transmission Assembly) remanufactured transmission often come in with complaints of TCC slip or shudder, code P1870 or P0894 and harsh 1-2 shift.

    The torque converter clutch regulator valve bore is very prone to wear causing the TCC slip complaints and related code. The TCC slip code leads to the harsh 1-2 upshift as the ECM recognized the TCC slip and commands high line pressure to avoid further TCC slippage and damage. For that reason, GM remanufactured SERTA transmissions usually have valve bodies that have been machined to allow the use of a larger .472” diameter TCC regulator and isolator valve. Over time those wear out the bore the same way the originally valve did, again leading to the same complaints.

    Features and benefits:

    This TransGo 4L6-ISO-3 kit features a drop-in USA-made hardened steel, oversized patented isolator valve. The redesign valve restores the hydraulic integrity of the circuit by utilizing previously unused and therefore unworn areas of the bore. In addition, it can be used without the included spring to work in vehicles with active fuel management (AFM). Lastly, this kit includes enough parts to fix three transmissions.

    • TCC slip or shudder
    • Code P1870 and P0894
    • Harsh 1-2 shift
    • Reduces future wear
    • (3) Drop-in USA-made hardened steel over-sized isolator valves
    • (3) Isolator valve springs