1994-2007 Cummins 5.9L 47/48RE Big Input Shaft Kit (22121B-08K)

The Sonnax Smart-Tech® Big Input Shaft Kit, 22121B-08K, is the ultimate solution to prevent input shaft spline twists and breakage in high-torque Chrysler 47RH, 47RE, and 48RE diesel applications. Compared to the best 300M 23-spline shafts, the Sonnax input shaft is 35% stronger at both the spline portion of the shaft and the sealing ring/cross-hole area of the shaft, eliminating all concerns of failure at these critical points.

The larger sealing ring and cross-hole area require a custom stator/pump cover assembly. The stator assembly features standard 48RE tube splines made of high-strength steel, improved retention in the stator body, 48RE matched pump porting, and special rubber seals to eliminate oil leakage between the cover and pump body.

The longer direct (front) clutch hub portion of the shaft has longer splines that allow for one extra (OE-thickness) direct friction plate when used with the included thinner billet aluminum direct piston, all while keeping OE-thickness steels, backing plate, OE waved retaining ring and OE clutch clearances.

Some common aftermarket modifications designed to include extra clutches require reduced steel thickness and decrease the heat absorption capacity of the clutch pack. Others reduce clearance and eliminate the waved retaining ring, which contributes to excess 2-3 shift overlap. The Sonnax kit avoids these problems by increasing the number of frictions from five to six, adding to the steel mass of the clutch pack, and maintaining the OE thickness backing plate and clearances for the optimum combination of increased capacity and durability.

Contents: Input Shaft - 35 Spline with Extended Hub, Stator Support Assembly, Direct Clutch Piston, Steel Clutch Plate .068" Thick, Seal Rings (3) 1 Extra, and Quad Ring Seals (4)

The through-holes and cross holes in Dodge shafts are designed by the OEM to optimize converter function. Some aftermarket shafts have smaller holes or are completely solid all the way through in an attempt to make them stronger. The theory is that packing more material into empty spaces makes shafts less prone to breaking, especially at the cross hole area. In reality, this is simply not true — shaft strength and durability have FAR more to do with manufacturing processes than whether there’s a hole down the center. Why?

Most all the load is carried on the OUTSIDE diameter of shafts, not the inside. Reducing cross-hole size concentrates stress around a smaller area, putting shafts at MORE risk for breaking, not less.The amount of added material on a solid input shaft amounts to LESS THAN 1% of its overall strength.The problems you risk by changing or eliminating oil flow paths are not worth it for the tiny amount of material and torque capacity gained. Inconsistent converter release, premature clutch failure and insufficient lockup apply pressure all can be traced back to poorly-designed aftermarket shafts.