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

SmartShell® Heavy Duty Reaction Shell Kit

Part No.


SmartShell® Heavy Duty Reaction Shell Kit
  • SmartShell® Heavy Duty Reaction Shell Kit

  • 77749-02k_customrollerclutchrace

  • 77749-02k_enclosedthrustbearing

  • 77749-02k_heavydutyreactionshell

  • 77749-02k_details

Small_77749-02k Small_77749-02k_customrollerclutchrace Small_77749-02k_enclosedthrustbearing Small_77749-02k_heavydutyreactionshell Small_77749-02k_details

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

SmartShell® Heavy Duty Reaction Shell Kit

Part No. 77749-02K

  • Heavy Duty Reaction Shell
  • Enclosed Thrust Bearing
  • Custom Roller Clutch Race

In GM 4L60, 4L60-E, 4L65-E and 4L70-E units, bulky aftermarket shells always fall short when splines continue to strip and the shells break under stress. A chronic problem with both OE and thicker aftermarket shells is failure of the rear planetary bearing. From daily jobs to extreme builds, the Sonnax SmartShell heavy-duty reaction shell kit 77749-02K is the only way to prevent shell failure AND protect the bearing.

The SmartShell avoids the weight found in traditional, heavy-duty aftermarket shells thanks to a unique combination of improved design and manufacturing for a super strength shell that's only slightly bulkier than OE. To prevent thrust loads from overwhelming the captured planetary bearing, the SmartShell features a larger bearing and custom roller clutch race. These parts re-route thrust loads through the carrier, completely bypassing the delicate bearing.

  • Stops spline stripping
  • Prevents hub breakage
  • Eliminates planetary bearing failure

Learn more about the Sonnax SmartShell

  • Patent No. 8,377,356

Related Parts

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Sonnax SmartShell® Video

Fix 4L60 series sun gear shell problems with BRAINS, not just brawn. The SmartShell is the first and only upgrade that protects the planetary assembly and also provides a reinforced shell.

Learn more about the Sonnax Smartshell

Contact a Sonnax Distributor to purchase this part.