August 01, 2019
Trucks equipped with Allison® 1000/2000/2400 transmissions can be subject to delayed, long or flare shifts. This can be caused by bore wear or minimal OE valve bore engagement at the exhaust backfill valve. If there is excess bore wear or lack of full valve-to-bore engagement, the exhaust backfill circuit can leak all residual pressure and result in the noted drivability complaints.
Sonnax exhaust backfill valve kit 37000-17K nearly doubles the amount of critical valve spool-to-bore engagement, both at the inboard and outboard areas of the bore, resulting in better sealing of the exhaust backfill circuit.
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.