Skip to content

Brand: Sonnax

Other Part Number: S121741WK

Type: Valve Body

Interchange Part Number: S116741VK

Items Included: Trim Valve & Spring Kit 

Manufacturer Part Number: 37000-12K

Universal Fitment: Yes

Vintage Part: No

Performance Part: Yes

1000/2000/2400

Trim Valve & Spring Kit
Part No. 37000-12K

Fits '00-'09 units only. The F-trim spring is applicable to '00-'05 valve body casting only.

Tooling Required:
  • 37000-TL12
The OE trim valve and spring configuration has a very conservative pressure curve, resulting in premature clutch wear in heavy-duty Allison® 1000/2000/2400 ('02-'09) applications. Clutch damage occurs when the TCM pressure control strategy is unable to adequately raise clutch pressure and shorten shift durations. Sonnax trim valve and spring kit 37000-12K includes A-, B- and F-trim valve springs and a A- and B- trim valves with recalibrated valve ratios, which is the only way to predictably improve clutch pressures and apply rates, resulting in more responsive clutch pressure .The F-trim bore in '00-'05 units contains an F-trim sleeve . This bore can be upgraded using the spring in this kit and Sonnax F-trim valve sleeve 37000-03.
  • 15% More clutch pressure & clamping force than OE
  • Firmer and shorter upshifts
  • Firmer TCC engagement
  • Improved engine braking on deceleration
  • A-Trim Valve & Spring
  • B-Trim Valve & Spring
  • F-Trim Spring

Use this text to share information about your product.