• Burnt clutches
  • Delayed engagement
  • Inadequate lubrication
  • Low pressure
  • Slips & flares
  • Soft shifts
  • TCC apply & release concerns
  • TCC codes


Loss of oil pressure due to worn components in critical oil circuits.


Zip Kit seals critical pressure losses. Drop-in parts install quickly and easily.

55-50SN, 55-51SN

Zip Kit®
Part No. AW55-50SN-ZIP

Also fits AF 23/33 and RE5F22A units.

View Instructions Find a Distributor

Sonnax Zip Kit AW55-50SN-ZIP targets the root cause of multiple complaints by sealing the critical circuit pressure losses in Aisin AW 55-50/51SN valve bodies. The kit contains uniquely designed parts to prevent the loss of pressures within the main line, lockup, solenoid and throttle signal circuits. The kit also seals multiple circuits known to suffer from end plug leakage. No special tools are required for installing these parts.

The Zip Kit quick guide provides clear and easy instructions on one sheet to get the unit sealed up and back on the road fast. In addition to general rebuilding tips and technical information, the technical booklet included in this kit contains vacuum testing information and locations at other key areas of the valve body.

  • Drop-in Zip Valve parts install quickly and easily, no reaming or special tools required
  • Uniquely designed parts address root causes of valve body complaints by sealing critical pressure circuits
  • Detailed technical booklet included with in-depth rebuild and inspection tips for comprehensive valve body repair
Learn More About Zip Valve™ Drop-In Repairs
  • Pressure Regulator Valve, Balance Pin, Retaining Clip & O-Rings 2 O-Rings, 1 Extra
  • O-Ringed End Plug Kit
  • Solenoid Relay Valve Kit
  • Solenoid Modulator Valve, Sleeve, Spacer Sleeve & Spring
  • Boost Valve & Sleeve
  • Lockup Relay Control Valve Kit
  • B5 Control Spring
  • LPC Accumulator Piston Kit
  • Lockup Control Valve Kit
  • Line Relief Spring Red
  • Secondary Regulator Valve, Spring & Seals 2 Seals, 1 Extra
  • B4 Release & Reverse Inhibit Springs (2) No Color
  • Cooler Bypass Spring Large, No Color
  • TCC Check Valve Springs (2) 1 Yellow, 1 White

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 Zip Kit® AW55-50SN-ZIP


Zip Kit® Video - The First Step in Correcting Common Shift Problems
Sonnax Zip Kit

The Sonnax ZIP KIT®

The First Step in Correcting Common Shift Problems

It's easy to restore and extend vehicle shift quality with Zip Kits. Uniquely designed, drop-in Sonnax parts target the root cause of valve body complaints and stop critical circuit pressure losses in the most common problem areas of the transmission.

Learn More About Sonnax Zip Kits