• 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 circuits.


Recover hydraulic control, restore normal shift operation and save the transmission control unit by installing Sonnax Zip Kit.

6T30, 6T40 (Gen. 2), 6T45 (Gen. 2), 6T50 (Gen. 2)

Zip Kit®
Part No. 6T40-GEN2-ZIP

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Sonnax Zip Kit 6T40-GEN2-ZIP targets the root cause of multiple concerns by sealing critical circuit pressure losses in GM 6T30 and second generation 6T40, 6T45 and 6T50 valve bodies. The kit contains uniquely designed parts to prevent the loss of pressures within the main line, clutch apply control, actuator feed and lockup control circuits. The kit also seals multiple circuits known to suffer from end plug leakage or poor checkball sealing. No separate 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 quickly. 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.

  • Simple parts install quickly with no reaming or 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
  • End Plugs (5)
  • O-Rings (7) 2 Extra
  • TCC Regulator Apply Valve, Shuttle Valve, End Plug, Spring & O-Rings (2) 1 Extra
  • AFL Valve, Sleeve, Spring & Retainer Clip
  • Checkballs (6)
  • Drill Bit .062" Dia. (Not shown)
  • Aluminum Plugs (2) .062" Dia, 1 Extra (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.

GM 6T30 & 6T40 (Gen. 2), 6T45 (Gen. 2), 6T50 (Gen. 2) Valve Body Layout

GM 6T30 & 6T40 (Gen. 2), 6T45 (Gen. 2), 6T50 (Gen. 2) Valve Body Layout
  • 6T30, 6T40 (Gen. 2), 6T45 (Gen. 2), 6T50 (Gen. 2) Zip Kit® 6T40-GEN2-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