• Broken parts due to excessive line pressure
  • Excess heat
  • Firm shifts
  • Flare shifts & bind-ups
  • Delayed engagement
  • Harsh engagement


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


Zip Kit seals critical pressure losses and restores and extends accumulator action. Drop-in parts install quickly and easily.

ZF6HP21, ZF6HP28, ZF6HP34

Zip Kit®
Part No. ZF6-GEN2-ZIP

View Instructions Find a Distributor

Sonnax Zip Kit ZF6-GEN2-ZIP targets the root cause of multiple complaints by sealing the critical circuit pressure losses in listed valve bodies. The kit contains uniquely designed parts to prevent the loss of pressures within the main line, solenoid regulator, reverse, clutch control and solenoid apply circuits with no special tools required.

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.

  • 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

This Zip Kit ZF6-GEN2-ZIP is designed for ZF6HP21/28/34 (Generation 2) applications only. A separate Zip Kit ZF6-6R60-ZIP is available for ZF6HP19/26/32 (Generation 1) and Ford 6R60/6R80 applications. To verify valve bodies, see this identification guide for further details.

  • Accumulator Piston Kit
  • Testing Nut
  • Testing End Plug
  • Pressure Regulator Sleeve
  • O-Ringed Internal End Plug Kit
  • Solenoid O-Rings 31 Various Sizes
  • O-Ringed End Plug Kit
  • Clutch A & E Control Boost Valve Kit

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.

ZF6HP21/28/34 (Gen. 2) Valve Body Layout

ZF6HP21/28/34 (Gen. 2) Valve Body Layout

  • ZF6HP21, ZF6HP28, ZF6HP34 Zip Kit® ZF6-GEN2-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