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

Input Drum Reinforcement Kit
Part No. 77733-02K

View Instructions

The GM 4L60, 4L60-E, 4L65-E and 4L70-E input drum assembly is known to crack where the input shaft is pressed into it (where the overrun clutch rides).

Sonnax offers a hardened steel sleeve that reinforces the input drum to prevent this failure. OE overrun pistons must be machined when using Sonnax input drum reinforcement kit 77733-02K.

  • Sleeve made from hardened chromoly steel
  • Can be installed in early- and late-model units*
  • Sleeve design will not block clutch feed oil

*Will not repair a cracked drum. Requires 96-earlier aluminum forward piston or Sonnax billet forward piston 77764-01, cannot be used with stamped steel forward piston.

  • Reinforcement Sleeve
  • Overrun Piston Inner Seal

February 22, 2016

Too Close For Comfort: Pinpointing 4L60-E Gear Train Assembly Problems

Steve Garrett

Topics: Transmission GM 4L70-E Transmission 4L60-E Transmission 4L65-E Transmission

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  • 77733 02k combo
  • 77733 02k