Continuous oscillation of the Forward and Reverse abuse valves in GM 4L60-E, 4L65-E and 4L70-E units creates bore wear, allowing clutch feed pressure to exhaust. This reduced clutch pressure causes slippage and burn-up. Reconditioning the bore and installing Sonnax oversized Forward and Reverse abuse valve kit re-establishes hydraulic integrity, eliminating clutch pressure loss. The Sonnax oversized replacement valve has extended spool lengths to provide additional sealing contact area. The stabilization flats on the inboard end of the spool maintain OE flow, but provide continual valve support while stroking. An annular groove has been added to prevent side loading and a new spring has been provided for the modified valve length. Sonnax oversized Forward and Reverse abuse valve kit 77754-58K fits either the Forward or Reverse abuse location and includes a replacement bore plug.
Vacuum testing at the port(s) indicated fails to hold the recommended minimum in-Hg, or if wear is visually detected.