4L60-E, 4L65-E, 4L70-E Transmission

Forward Accumulator Piston
Part No. 74927-AP

OE Part No. 8686017 or 24200126

In GM 4L60-E, 4L65-E and 4L70-E units, it is common for the plastic Forward accumulator piston to wear or crack and older aluminum piston bores to wear from repeated reciprocation. This causes a loss of fluid, resulting in delayed engagement, slips, burnt clutches and/or bands. Sonnax aluminum Forward accumulator piston 74927-AP eliminates the cracking problem and restores hydraulic integrity at the pin bore. The drop-in Zip Valve™ part installs quickly and easily.

Symptoms:

  • Cracked pistons
  • Burnt clutches
  • Burnt bands
  • Forward slip
  • Delayed engagement
  • Aluminum pistons wear at the pin bore

Cause:

Wear at the piston pin bore due to repeated reciprocation and/or cracks in the plastic accumulator piston.

Correction:

Sonnax drop-in, aluminum forward accumulator piston is a direct replacement for the OE plastic piston and restores sealing integrity at the pin bore.