Vehicles with Aisin Warner 55-50SN or 55-51SN, GM AF23/33, or Jatco/Nissan RE5F22A transmissions may exhibit insufficient line rise in Reverse, delayed or slipping Reverse, and/or a burnt Reverse clutch. Continuous oscillation of the OE boost valve within the boost sleeve causes premature wear, creating a path for reverse apply boost pressure to exhaust and causing these concerns. Excess clearance/wear at the sleeve to bore interface can allow throttle signal (SLT) pressure to exhaust resulting in various shfit complaints. Installing Sonnax boost valve kit 59947-07K eliminates pressure loss, restoring proper line rise and robust Reverse action.
Sonnax valve body layouts provide a detailed overview of individual units making it quick and easy to determine what’s available for the specific valve body you’re working on. See all Sonnax valve body layouts.
Vacuum testing at the port(s) indicated fails to hold the recommended minimum in-Hg, or if wear is visually detected.