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  • Bonded piston seal delamination
  • Direct clutch failure
  • OD band distress
  • Low line pressure in Forward
  • No Forward unless RPM increased


Leakage of forward or direct clutch oil due to worn accumulator bores.


The Sonnax 2-3 accumulator kit includes two sleeves, a replacement piston and two D-rings so the case may be salvaged without machining, restoring proper piston clearances.

4R70E, 4R70W, 4R75E, 4R75W, AOD, AODE

2-3 Accumulator Piston Kit
Part No. 76890-21K

View Instructions

Forward or direct clutch oil pressure loss can often be traced to wear and scoring of the 2-3 accumulator bores. Previously, the only lasting correction was to replace the case. The Sonnax 2-3 accumulator piston and sleeve kit, 76890-21K, restores forward line pressure and salvages damaged cases by repairing damaged 2-3 accumulator bores on AOD, AODE & 4R70W and 4R75W units. Press-in sleeves and a matched piston restore pressures and install easily, without machining or special tools.

  • Salvage transmission cases with damaged accumulator bore.
  • Kit installs easily, with no special tools required.
  • Works in AOD & E and 4R70W and 4R75W units.
  • Eliminates concerns about bonded piston seal delamination.
  • Piston
  • Sleeves (2)
  • D-Ring Seals (2)

September 30, 2005

Anatomy of a Transmission: Oil Flow in the Pump-PR-Converter-Cooler Lube Circuits

Gregg Nader

Topics: Diagnostics And Theory Transmission

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  • 76890 21k combo
  • 76890 21k