• Burnt clutches
  • Line pressure instability
  • Loss of fuel economy
  • No line rise
  • Pressure loss
  • Shift concerns
  • TCC apply & release concerns
  • TCC codes


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


Recover hydraulic control and restore normal shift operation by installing Sonnax Zip Kit.

6F50, 6F55

Zip Kit®
Part No. 6F50-ZIP

View Instructions Find a Distributor

Sonnax Zip Kit 6F50-ZIP targets the root cause of multiple concerns by sealing critical circuit pressure losses in the Ford 6F50 and 6F55 valve bodies. The kit contains uniquely designed parts to prevent the loss of pressures within the main line, clutch apply control, solenoid feed and lockup control circuits. 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 information and locations at other key areas of the valve body.

  • No reaming required
  • Installs quickly with no special tools required
  • Uniquely designed parts address root causes of valve body concerns by sealing critical pressure circuits
  • Detailed technical booklet included with in-depth rebuild and inspection tips for comprehensive valve body repair
  • O-Ringed End Plug Kit
  • Isolator Valve Kit
  • Checkballs (7) .250" Dia., 1 extra
  • TCC Regulator Valve, Spring, Shuttle Valve, End Plug & O-Rings 2 O-Rings, 1 extra
  • AFL Valve, Sleeve, Spring & Clip
  • Aluminum Plugs (2) 1 Extra, (not shown)
  • Drill Bit .062" Dia., (not shown)

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 6F50, 6F55 Valve Body Layout

Ford 6F50, 6F55 Valve Body Layout
  • 6F50, 6F55 Zip Kit® 6F50-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