sonnax-black Facebook-color LinkedIn-color maillink printlink r_and_r_only SERVOFIX-logo-web Twitter-color VBFIX-logo-web video-logo-web warranty_only Youtube-color


  • 3rd Clutch distress
  • Damage from broken spring
  • Worn accumulator piston pin bore
  • 2-3 Soft
  • 4-3 Kickdown


Normal wear and uneven loading from spring.


Install the Sonnax replacement piston with increased bore length for more piston-to-pin support and greater durability


2-3 Accumulator Piston
Part No. 72871-01

1994 & later

View Instructions

The piston bore in 4T80-E units is prone to wear, either through normal operation or uneven loading from the spring. The Sonnax replacement piston 72871-01 provides more piston-to-pin support and greater durability than OE replacements.

  • Increased bore length for more piston-to-pin support.
  • Machined from high-quality aluminum.
  • More durable than OE replacements.
  • Piston accepts standard OE or replacement seals.

This piston should not be used in a first-design 2-3 accumulator found in '93 models. These units do NOT have the second bumper spring on the top portion of the accumulator piston. If the large spring is broken, replace with GM part number 8684827

September 30, 2005

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

Gregg Nader

Topics: Diagnostics And Theory Transmission

Read Now
  • 72871 01 combo
  • 72871 01