Symptoms:

  • Delayed Reverse
  • Erratic Reverse pressure
  • Delayed Drive
  • Soft upshifts
  • Harsh upshifts

Cause:

The valve within the sleeve separates reverse boost oil from throttle signal (SLT) oil. Pressure in reverse can either be delayed or added to SLT, which results in very high reverse pressure. If the sleeve is worn and selector is not in Reverse, SLT is allowed to vent at the manual valve, reducing line rise, which affects engagements and shift quality.

Correction:

The tightly toleranced, drop-in replacement Sonnax valve and sleeve assembly restores proper hydraulic clearances and uses upgraded materials to prevent wear.

55-50SN, 55-51SN

Boost Valve Kit
Part No. 59947-07K

You need this if... View Instructions Find a Distributor
  • Sleeve is manufactured from highly wear-resistant billet aluminum.
  • Valve is made of hard-coat anodized aluminum to prevent wear.

Also fits AW55-51SN, AF 23/33 and RE5F22A units. The 59947-07K should not be usedwith Sonnax oversized pressure regulator valve 59947-12K.

  • Valve
  • Sleeve

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.

Aisin AW 55-50SN, 55-51SN Valve Body Layout

Aisin AW 55-50SN, 55-51SN Valve Body Layout
  • 55-50SN, 55-51SN Boost Valve Kit 59947-07K
  • 55-50SN, 55-51SN Boost Valve Kit 59947-07K

You need this if...

A vacuum test of the sleeve assembly (while in the bore at the outboard reverse feed port indicated) gives less than 18" of vacuum, or if a Wet Air Test at the same location results in leakage at the neighboring exhaust port.

55-50SN, 55-51SN Boost Valve Kit Vacuum Test Locations