47RE, 47RH, 48RE

Smart-Tech® High Capacity Input Shaft & Piston Kit

Part No.


Smart-Tech® High Capacity Input Shaft & Piston Kit
  • Smart-Tech® High Capacity Input Shaft & Piston Kit

  • 22121b-02k_combo

  • 22121b-02k_comparison

Small_22121b-02k Small_22121b-02k_combo Small_22121b-02k_comparison

47RE, 47RH, 48RE

Smart-Tech® High Capacity Input Shaft & Piston Kit

Part No. 22121B-02K

  • Input Shaft with Extended Hub
  • Direct Clutch Piston with Anti-Rotation Tabs
  • Steel Clutch Plate .068" with Missing Lugs

Based on the ultra-durable, one-piece Sonnax heavy duty input shaft 22121B-01 for Chrysler 47RE, 47RH, and 48RE units, the Smart-Tech high capacity 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%
  • Made from forged 300M steel
  • Heavy-duty, one-piece design eliminates weak connection between input shaft and forward clutch hub
  • No change to backing plate thickness or retaining ring

Related Parts

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Unmatched Durability & Performance with the #1 Dodge Diesel Heavy Duty Input Shafts

Sonnax heavy duty input shafts for 48RE trucks come with durability and performance features that are second to none. This video showcases how the original one-piece input shaft and the newer Smart-Tech® kit with 20% more clutch capacity are designed from the ground up to deliver the absolute best in transmission performance.

Contact a Sonnax Distributor to purchase this part.