Warning:

This kit must be used with a ’97-later stamped steel forward piston, it cannot be used with '96-earlier aluminum forward piston or Sonnax billet forward piston 77764-01.

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

Input Drum Reinforcement Kit
Part No. 77733-51K

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The GM 4L60, 4L60-E, 4L65-E and 4L70-E input drum assembly is known to crack and strip out splines where the input shaft is pressed into it (where the overrun piston rides). Sonnax offers a hardened steel sleeve that reinforces the input drum to prevent this failure. Sonnax input drum reinforcement kit 77733-51K includes a custom manufactured overrun piston designed for use only with a stamped steel forward piston, eliminating the need to use aluminum forward pistons.

  • Custom overrun piston works with steel forward piston
  • Chromoly steel sleeve design will not block clutch feed oil
  • Universal design fits both early- and late-model units
  • Reinforcement Sleeve
  • Overrun Piston Inner Seal
  • Overrun Piston
  • Overrun Piston Outer Seal
  • 4L60, 4L60-E, 4L65-E, 4L70-E Input Drum Reinforcement Kit 77733-51K