Common complaints with '93-later GM 4T60-E units are falling out of lockup hot, codes 39, 740 and 1870, adverse lockup in cold weather, torque converter shudder and burn-up of the TCC lining. These complaints can be caused by a worn TCC regulator sleeve and/or a worn valve body bore in the isolator valve area. The TCC regulator sleeve design was changed in '93, and this newer design has an aluminum sleeve with a steel valve that continuously oscillates within the sleeve. This motion eventually wears the inner diameter of the sleeve and results in excessive leakage. This leakage allows the TCC apply oil to exhaust to the sump. Leakage also is caused by the hardened steel isolator valve wearing the aluminum valve body bore. This allows converter oil charge reduction and PWM boost oil loss. Install Sonnax TCC regulator and isolator valve kit 84754-01K to resolve these problems.

• TCC regulator sleeve is made from highly wear-resistant aluminum specifically designed to prevent excessive wear
• Hardcoat anodized aluminum TCC valve combats premature wear
• Isolator valve is longer than OE in order to contact the entire length of the valve bore
• Larger spool diameter and feed orifice have been added to the isolator valveto allow PWM oil to increase TCC oil boost
• Isolator valve sleeve salvages valve bodies with excessively worn isolator valve bores which are not corrected by the use of 84754-01K alone