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  • Erratic buzz
  • Uncontrolled pressure in Reverse
  • Low line rise
  • High line pressure in Reverse
  • Soft shifts
  • Delayed engagement


Wear at the pressure regulator valve bore allows vital main line pressure to exhaust and reduces converter charge pressure


Refurbish the valve bore and install the Sonnax oversized valve and spring to restore proper hydraulic function and prevent future wear.


Oversized Pressure Regulator Valve Kit
Part No. 56947J-39K

You need this if... View Instructions

As the valve bore wears at the inboard spool, line pressure escalates with increased temperature and the pressure regulator valve does not stroke, reducing converter charge. As line pressure goes up, servo covers and pistons have excess pressure in reverse. Delayed engagements occur as the converter feed is reduced with excess bore wear. Line pressure will be reduced as the circuits between line, converter and exhaust wear. The Sonnax pressure regulator valve kit 56947J-39K can restore proper hydraulic function and prevent future wear.

  • Hard-coat anodized aluminum valve prevents wear and has modified spool length to maintain OE pressure curve
  • Includes replacement spring to restore OE pressures with oversized valve
  • Valve
  • Spring

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 5R55N Valve Body Layout

Ford 5r55n
  • 56947j 39k combo
  • 56947j 39k

You need this if...

Wear is visible or if vacuum test results in leakage as indicated:

A. Balanceline pressure port

B. Line pressure port

C. Converter charge pressure port

  • 56947j 39k test