Fitment

• Fits 300mm reluctor-style GM units:
  • 4L60-E
  • 4L65-E
  • 4L70-E

Why You Need This Kit

The OE GM 4L60-E / 4L65-E / 4L70-E input housing is a known weak link and a primary cause of 3-4 clutch burnup in performance applications.
Problems with the OE design:

• Weak backing plate flexes during clutch apply
• Causes uneven heat build-up in the limited 3-4 clutch space
• Leads to premature 3-4 clutch failure

The Sonnax Smart-Tech® Input Housing solves this by:

• Making room for a taller, physically larger 3-4 clutch pack
• Anchoring the pack with a much stronger backing plate
• Dramatically increasing clutch capacity and protecting against destructive heat

Key Features & Benefits

• Heavy Duty Input Shaft

  • High-strength, performance-ready shaft
  • Sonnax-exclusive refinements to help prevent stress crack failures
  • Housing and shaft also available separately

• Increased 3-4 Clutch Capacity
  Physically larger clutch pack area for more 3-4 capacity without sacrificing durability.
  Compatible with:

  • 8 frictions (.067") with 7 steels (.095"), or
  • 9 frictions (.062") with 8 steels (.077")

• Anchored Backing Plate Design

  • Keeps clutches flat and parallel
  • Stops backing plate flex and distortion
  • Greatly reduces heat build-up and 3-4 failure

• Reinforced & Treated Housing

  • Specially treated housing is highly resistant to fatigue failure
  • Steel reinforcement sleeve prevents spline area breakage
  • Custom backing plate replaces OE retaining ring to eliminate blowout risk

• Premium Alto G3 Powerpack

  • Includes Alto top-of-the-line High Performance G3 3-4 Powerpack clutches
  • Specifically engineered for the Sonnax Smart-Tech drum
  • Optimized for high horsepower, high pressure builds and superior heat resistance

Requirements & Compatibility Notes

This kit requires the following later-model components:

• ’91-later 3-4 apply ring
• ’97-later ring gear
• ’97-later stamped steel forward piston

Not compatible with:

• Aluminum forward piston
• Sonnax billet forward piston 77764-01

Refer to the installation instructions for complete details.

Kit Contents

• Smart-Tech® Input Housing with 300mm reluctor-style Input Shaft Assembly
• Alto G3 High Performance 3-4 Powerpack clutches
• PTFE-impregnated Rear Stator Support Bushing
• Input Drum Reinforcement Sleeve (installed)
• Overrun Piston
• Overrun Piston Inner Seal
• Overrun Piston Outer Seal
• 3-4 Clutch Apply Plate
• 3-4 Clutch Return Springs (10)
• Bolt-on Anchor Plate
• Socket Head Cap Screws (15)

Need the housing or shaft only?
This Smart-Tech housing and heavy duty input shaft are also available individually.