Symptoms:

  • 4-3 Neutral
  • No 4th
  • Burnt OD band

Cause:

Wear at the innermost bore of the overdrive servo regulator valve allows regulated overdrive servo oil to leak to exhaust, preventing proper regulation of the overdrive servo.

Correction:

Recondition the valve bore and install Sonnax oversized overdrive servo regulator valve kit to restore proper hydraulic function of the overdrive servo circuit.
  • 4R70E, 4R70W, 4R75E, 4R75W Oversized Overdrive Servo Regulator Valve Kit 76948-59K
  • 4R70E, 4R70W, 4R75E, 4R75W Oversized Overdrive Servo Regulator Valve Kit 76948-59K

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.

4R70E, 4R70W, 4R75E, 4R75W Oversized Overdrive Servo Regulator Valve Kit Vacuum Test Locations