Symptoms:

  • Flare shifts
  • Long shifts
  • Delayed shifts

Cause:

Wear of the exhaust backfill casting bore, and lack of full OE valve bore engagement can allow clutch backfill pressure to exhaust, resulting in slower clutch apply.

Correction:

Sonnax exhaust backfill valve kit restores hydraulic integrity and has been redesigned with a longer spool for better engagement in both the inboard and outboard ports to better seal the backfill circuit.

1000/2000/2400

Exhaust Backfill Valve Kit
Part No. 37000-17K

Fits '00–'15 units.

You need this if... View Instructions Find a Distributor

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.

  • 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
  • Valve
  • Spring
  • 37000 17k combo
  • 37000 17k

You need this if...

Vacuum testing at the port(s) indicated fails to hold the recommended minimum in-Hg, or if wear is visually detected.

  • 37000 17k test