Input Drum Reinforcement Kit

The General Motors 4L60/65/70E input drum assemblies have been known to prematurely fail caused by cracking where the input shaft is pressed into it. This is where the overrun piston rides. 

This fracturing can become even more prevalent in units with larger wheel/ tire combinations and higher torque units where torsional fatigue becomes even more prominent.

The new 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.