• 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, 4L65-E, 4L70-E

Batwing Washer
Part No. 77731-05

Fits 4-pinion rear planetary.

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Sonnax batwing washer 77731-05 is a direct replacement for worn or damaged OE washers in listed GM transmissions. Made from solid bronze, Sonnax washers eliminate spin and protect against rapid wear.

  • 4L60, 4L60-E, 4L65-E, 4L70-E Batwing Washer 77731-05