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  • Clutch failure
  • Band failure
  • Non-adjustable (high) throttle pressure
  • 1-2 Flare
  • 2-3 Flare
  • 2-1 Clunk
  • Harsh Reverse


The boost valve wears the inside diameter of the boost sleeve, allowing TV/EPC and reverse oil leakage.


These replacement assemblies provide wear-resistant materials, minimum clearance for restored pressure control, and optional O-rings for positive sealing within the bore.


Boost Valve Kit
Part No. 96201-01K

Fits all except 3.0 Liter 12 valve, O-ring style

View Instructions

Vehicles with an AXOD, AXODE, AX4S or AX4N transmission frequently have flare 1-2 & 2-3 upshifts, high pressure, harsh reverse (300 psi), 2-1 downshift clunk, non-adjustable throttle pressure, and clutch or band failure from poor line rise. This is caused by wear on the inside bore of the boost sleeve allowing TV/EPC and/or reverse oil to either leak to exhaust or cross leak. Sonnax offers boost valve kits for both 3.0 and 3.8 liter applications and sleeves with or without O-rings (factory style) to eliminate the above problems.

  • Sleeves are made from high-quality aluminum to prevent wear.
  • Valves are hard-anodized for longer life.
  • O-ring sleeves prevent leakage between the sleeve and valve body bore.
  • Available in two sizes: 96201-12K (O-ring style) and 96201-13K (factory style) with a small diameter boost valve of .475"; 96201-01K (O-ring style) and 96201-08K (factory style) with a small diameter boost valve of .491".
  • Sleeve
  • Valve
  • O-Rings (2)

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.

Ford AX4N/4F50N Valve Body Layout

Ford ax4n 450n
  • 96201 01k combo
  • 96201 01k