Symptoms:

  • 2-3 Harsh
  • 3-4 Harsh
  • No 5th
  • 4-5 Harsh
  • Low Reverse pressure
  • C2 Clutch burned
  • B1 Clutches burned
  • B2 Clutches burned
  • High line pressure in Reverse

Cause:

Oscillation of the shift pressure control valve within its sleeve causes wear, which will allow Drive or Reverse pressure being routed to the B2, B1 or C2 clutch to exhaust or cross leak. This will result in shift complaints and burnt clutches.

Correction:

Restore proper hydraulic control by replacing worn parts with the improved, drop-in Sonnax shift pressure control valve kit.

55-50SN, 55-51SN

Shift Pressure Control Valve Kit
Part No. 59947-38K

Also fits AF23/33 and RE5F22A.

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

The shift pressure control valve in Aisin AW 55-50SN and 55-51SN units is biased by spring force and shift control (SLS) fluid pressure. This valve regulates Drive and Reverse fluid pressure to control the apply of the second clutch (B2), the second coast clutch (B1) or the direct clutch (C2). The constant oscillation of the valve wears the cast aluminum sleeve, allowing Drive and Reverse fluid pressure to leak and cause shift complaints and burnt clutches. Sonnax shift pressure control valve kit 59947-38K uses upgraded materials and annular grooves on the valve to correct the problem and prevent future wear.

  • Hardcoat anodized aluminum valve combats premature wear
  • Annular grooves on the valve hydraulically center it in the bore to prevent sleeve wear
  • 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 Shift Pressure Control Valve Kit 59947-38K
  • 55-50SN, 55-51SN Shift Pressure Control Valve Kit 59947-38K

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.

55-50SN, 55-51SN Shift Pressure Control Valve Kit Vacuum Test Locations