• Planetary failure
  • Planetary wear


Insufficient lube oil and/or excessive clearances.


This kit offers replacement parts for rebuilding damaged rear planet assemblies and gives rebuilders the option of replacing only the worn components.

4L60, 4L60-E, 4L70-E, 4L70-E

Round Washer
Part No. 77731-04

4-Pinion rear planetary

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Sonnax round washer 77731-04 is a direct replacement for worn or damaged OE washers in four-pinion rear planetary assemblies in listed GM transmissions. The Sonnax washer is made from through-hardened steel to help eliminate needle roller thrust wear.

  • 4L60, 4L60-E, 4L70-E, 4L70-E Round Washer 77731-04