GM TH700r4 and 4L60E series reaction shafts used in high-torque applications — and especially in heavy vehicles — suffer from two common issues that require replacement: The splines that engage the rear planet can twist and the splines that engage the ring gear fret/wear. OE and other aftermarket versions are made from lower-strength, plain carbon steel. Sonnax heavy-duty reaction shaft 74602-01K is made from high-strength chromoly steel alloy to eliminate spline twists and wear.

The shaft kit includes a shim and two bearings. One bearing is for the shaft-to-reaction shell, the other bearing plus shim combination is for the shaft-to-front carrier and making it a universal fit for all input carrier styles. This includes all four- and five-pinion carriers found in early 700-R4, 4L60-E, and 4L65-E units including the Sonnax 2.84 ratio six-pinion input carrier kit as well as late-style four- and five-pinion 4L60-E and 4L70-E carriers with lip-style bearings.

• Prevents spline twist and wear
• High-strength alloy outperforms all other OE and aftermarket shaft material
• Universal shaft design plus included bearings and shim allow use with any input carrier style