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  • Gear ratio & solenoid codes
  • Low line rise
  • Soft shifts
  • Erratic shifts
  • No 3rd when hot
  • No 4th when hot
  • 2nd Gear starts
  • Delayed Forward
  • TCC apply concerns


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


Zip Kit seals critical pressure losses

4R44E, 4R55E, 5R44E, 5R55E

Zip Kit®
Part No. 4R44E-5R55E-ZIP

View Instructions

Sonnax Zip Kit 4R44E-5R55E-ZIP targets the root cause of multiple complaints by sealing the critical circuit pressure losses in the Ford 4R44E, 4R55E, 5R44E and 5R55E valve bodies. The kit contains uniquely designed parts to prevent the loss of pressures within the main line, EPC, solenoid feed and converter circuits. This kit also includes modifications that provide firmer shifts, improves intermediate servo and direct clutch pressure, and improves TCC apply. The kit also seals multiple circuits known to suffer from end plug leakage or poor checkball sealing. 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 and additional repair options for higher mileage units or for repairing specific complaints which are beyond the scope of this kit.

  • No Reaming required
  • Installs quickly with no special tools required
  • Uniquely designed parts address root cause 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
  • Forward Modulator Valve, PTFE Seal, End Plug, Spring, & O-Ring Large O-Ring
  • Boost Valve & Sleeve Kit
  • Reverse Modulator End Plug & O-Rings 2 Medium O-Rings
  • Kick Downshift, Manual Low & Throttle Downshift End Plugs (2) 1 Large, 1 Small
  • Kick Downshift, Manual Low & Throttle Downshift O-Rings (6) 2 Large, 4 Small
  • Extra End Plug O-Rings (6) 2 Large, 2 Medium, 2 Small
  • Checkballs (4) Plastic
  • EPC Limit Valve
  • Lube Orifice Plug
  • “L” Pins (2)
  • TCC Apply & OD Servo Apply Pressure Modification Drill Bits (4) .055” dia., .062” dia., .072” dia. & .110” dia. (Not Shown)
  • Plug Aluminum, .062” (Not Shown)
  • Shift Solenoid O-Rings (8) 4 Small, 4 Large (Not Shown)
  • 2-3/3-4 Shift Valve End Plug & O-Rings 2 Small O-Rings
  • 1-2/2-3 Shift Valve End Plug & O-Rings 2 Medium O-Rings
  • Converter Regulator Valve End Plug, Spring, & O-Rings 2 Large O-Rings

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 4R/5R44E, 4R/5R55E Valve Body Layout

Ford 4r 5r44e thumb

May 21, 2013

Ford 4R44E, 4R55E, 5R44E, 5R55E Vacuum Test Guide

Topics: Vacuum Test Guides Vacuum Testing Transmission Ford 4R44E Transmission 4R55E Transmission 5R44E Transmission 5R55E Transmission

Read Now

July 15, 2014

Zip Kit® Video - The first step in correcting common shift problems.

Topics: Diagnostics And Theory Transmission

Watch Now
  • 4r44e 5r55e zip

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 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