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 S121741HK 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. Lengthened critical spool operate in non-worn portion of bore for added stability and wear prevention; Annular grooves help center valve in bore to reduce future side-load wear; Hardcoat anodized aluminum valve combats premature wear; Drop-in Zip Valve™ parts install quickly and easily
Valve Kit; Exhaust Backfill
