Based on the ultra-durable, one-piece Sonnax heavy duty input shaft 22121B-01 for Chrysler 47RE, 47RH, and 48RE units, the Smart-Tech input shaft and piston kit 22121B-02K has a hub with longer direct (front) clutch splines. Combining longer splines with a thinner billet aluminum direct piston allows for one extra (OE-thickness) direct friction plate, 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 excessive 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.

• Kit increases direct clutch capacity by 20%
• Custom forged from ultra-high strength 300M billet steel
• One-piece design eliminates weak connection between input shaft and forward clutch hub
• No change to backing plate thickness or retaining ring