• 2-4 Band burned
  • 4th Band servo piston breakage
  • 1-2 Quality poor
  • No 4th
  • 4th Slip
  • 3-4 Concerns


The overdrive servo piston cracks, allowing apply oil to leak. In addition, the OE servo cover bolts are not hard enough, which causes the cover to come loose, allowing the piston to cock and break.


The Sonnax overdrive servo piston is made from stronger materials to prevent cracking, while the hardened bolts included in the kit prevent the cover from coming loose.


Overdrive Servo Piston Kit
Part No. 62170-01K

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The overdrive servo piston in Jatco/Nissan JR403E units is prone to cracking, allowing apply oil leakage that causes poor 3-4 shift quality and burned bands. The OE servo cover bolts stretch and break under normal use. As the cover becomes loose, it allows the piston to cock and break. Sonnax overdrive servo piston pit 62170-01K is thicker and stronger and will not break like the OE pistons do.

  • Piston is made from billet aluminum for greater strength and wear resistance
  • The 88mm (3.46") 4th piston can be used to upgrade from the smaller 75mm (2.953") 4th piston when used with a larger piston housing
  • High-strength bolts will not stretch, and keep cover firmly secured

Replaces OE 88mm piston. Will also upgrade 75mm piston if used with new piston housing.

  • Servo Piston 88mm
  • D-Ring
  • Bolts 6mm, Hardened
  • JR403E Overdrive Servo Piston Kit 62170-01K
  • JR403E Overdrive Servo Piston Kit 62170-01K