• Soft shifts
  • Poor shift quality
  • Reverse shudder
  • Direct clutch failure
  • Low line rise


Excess boost sleeve wear prevents proper line rise.


Recover hydraulic control and renew line rise performance by installing Sonnax drop-in boost valve kit


Boost Valve Kit
Part No. 36941-01K

'76-Earlier, clicker-style units

You need this if... View Instructions Find a Distributor

When rebuilding high performance or heavy-duty Ford C6 transmissions, it is common to find a worn boost sleeve in the clicker-style valve body. This wear causes poor line rise, which results in erratic shift timing, Reverse shudder or direct clutch failure. This can be caused by the reciprocating boost valve wearing the inside diameter of the boost sleeve. When this occurs, oil that enters the modulated line pressure orifice leaks past the boost valve and exhausts through the Reverse orifice, resulting in poor or no line rise. The outside diameter of the boost sleeve may allow some leakage through the valve body, which can result in insufficient line rise.

Sonnax boost valve kit 36941-01K eliminates the above problems. Replace the boost valve and sleeve to restore performance and to reduce the chance of premature failure.

  • Sleeve is manufactured from highly wear-resistant aluminum alloy
  • Hardcoat anodized valve combats premature wear
  • Drop-in Zip Valve parts install quickly and easily
Learn More About Zip Valve™ Drop-In Repairs

A number of boost valve kits are available for this unit:

  • Normal line pressure boost (gas ratio): Kits 36946-01K, 36946-04K and 36941-01K.
  • Increased line pressure boost (diesel ratio): Kits 36946-02K and 36946-03K are recommended for all heavy-duty applications.
  • Kit 36941-01K works in early model "clicker" with screw on boost valve end plate.
  • Kits 36946-01K, 36946-02K and 36941-01K include O-rings to provide additional protection against both cross-leakage and oil exhausting through the valve body bore.
  • Valve
  • Sleeve
  • O-Rings (3)
  • C6 Boost Valve Kit 36941-01K
  • C6 Boost Valve Kit 36941-01K

You need this if...

Vacuum testing at the port(s) indicated fails to hold the recommended minimum in-Hg, or if wear is visually detected.

C6 Boost Valve Kit Vacuum Test Locations