Sonnax Ford 4R100 Transmission TCC Control Plunger Valve Kit Symptoms: Lockup shudder TCC cycling Cause: Wear at the TCC control sleeve due to continuous plunger valve oscillation allows valuable oil leakage. Correction: This tightly toleranced replacement plunger valve kit restores hydraulic integrity for proper TCC control. 4R100 PWM units use a plunger valve assembly and coil spring to cushion the TCC control valve. That assembly uses regulated converter pressure as a variable hydraulic spring to control the rate of TCC apply. Continuous oscillation of the TCC control plunger valve wears the sleeve ID, allowing regulated converter pressure leakage. This can result in premature or bumpy TCC apply and/or shudder. Sonnax offers a drop-in replacement assembly, 36424-08K. Sleeve is manufactured from highly wear-resistant aluminum alloy. Aluminum valve has been hard-anodized to also prevent excessive wear. Parts are held to tight tolerances to restore the hydraulic integrity of the assembly. NOTE: Non-PWM 4R100 units do not have a TCC control plunger valve assembly.