4L60E Sonanx Input Drum, 300mm

4L60E Sonanx Input Drum, 300mm

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Limitations of the GM 4L60 series OE input housing are the root cause of 3-4 burnup in performance applications. The weak OE backing plate flexes during clutch apply, allowing heat to build up unevenly within the clutch pack’s limited space. Stop the flex and you stop 3-4 clutch failure.

Sonnax Smart-Tech input housing kit 77733-11KA makes room for a taller clutch pack anchored in place by a stronger backing plate — the most reliable way to increase clutch capacity and protect against destructive heat.

To avoid the problems found with older, OE housing designs, Sonnax starts with the latest production, new housings from GM. These improved housings have splines for the input shaft that are cut at minimum spec for reliable shaft retention and sealing. The housings also benefit from added material for a thicker, more consistent cross-section that protects against breakage.

Smart-Tech input housing kit with heavy duty input shaft 77733-11KA fits 300mm non-reluctor style units. The high-strength shaft features many unique refinements available only from Sonnax, including a unique design that protects against failure from stress cracks. Both the housing and shaft also are available separately.

  • Physically larger clutch pack area for increased 3-4 clutch capacity without sacrificing clutch durability. Use your choice of:
    • Eight .067" frictions with seven .095" steels
    • Nine .062" frictions with eight .077" steels
  • Anchored backing plate keeps clutches parallel to stop the flexing and distortion that leads to heat build-up
  • 100% New housing optimizes input shaft fitment and is further upgraded for significantly more resistant to fatigue failure
  • Steel reinforcement sleeve prevents breakage in the spline area
  • Custom backing plate replaces OE retaining ring to eliminate risk of blowout

Requires '91-later 3-4 apply ring; requires '87-later ring gear; requires '97-later stamped steel forward piston. Cannot be used with aluminum forward piston or Sonnax billet forward piston 77764-01. See instructions for further detail.

  • Smart-Tech Input Housing with 300mm Non-Reluctor Style Input Shaft Assembly
  • Bolt-on Anchor Plate
  • 3-4 Clutch Apply Plate
  • 3-4 Clutch Return Springs (10)
  • Input Drum Reinforcement Sleeve installed
  • Overrun Piston
  • Overrun Piston Inner Seal
  • Overrun Piston Outer Seal
  • PTFE Impregnated Rear Stator Support Bushing
  • Socket Head Cap Screws (15)

  • 8,857,592


Harness that Horsepower! Your Guide to a Sonnax 4L60/E Level 3 Performance Build

Eliminate 3-4 Clutch Failure with the Smart-Tech® Input Housing

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