Printpartsummary
Symptoms:
  • 2-3 Harsh
  • 3-4 Harsh
  • 4-5 Harsh
  • B1 Clutch burned
  • B2 Clutch burned
  • C2 Clutch burned
  • High line pressure in Reverse
  • Low Reverse pressure
  • No 5th
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 kit.

55-50SN, 55-51SN

Shift Pressure Control Valve Kit

Part No.

59947-38K

Shift Pressure Control Valve Kit
  • 59947-38k_combo

  • Shift Pressure Control Valve Kit

Small_59947-38k_combo Small_59947-38k

55-50SN, 55-51SN

Shift Pressure Control Valve Kit

Part No. 59947-38K

  • Valve
  • Sleeve

Also fits Aisin AW 55-51SN, AF 23/33 and RE5F22A units.

Complaint:

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

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 kit.

The shift pressure control valve in Aisin AW 55-50SN 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. The drop-in 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.

  • Valve is hardcoat anodized to reduce wear
  • Annular grooves on the valve hydraulically center it in the bore to prevent sleeve wear

Related Parts

You need this if...

A vacuum test at the port indicated fails to hold at least 18 in-Hg, or if visual wear is detected in the sleeve.

  • Test Locations

Click here to view PDF if instructions do not appear below.

It appears you don't have a PDF plugin for this browser. Click here to view the PDF file.

Valve Body Layouts

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.

Valve Body Layout Aisin AW 55-50SN
Contact a Sonnax Distributor to purchase this part.