Sonnax Smart-Tech® Overdrive Clutch Housing Kit

Sonnax Smart-Tech® Overdrive Clutch Housing Kit

Transtar Industries & Sonnax

Transtar's community of suppliers represents the most trusted and experienced in the industry. Sonnax shares our vision and meets the premium standards we set for all of our product offerings. We rely on the best aftermarket and OE suppliers in the industry. 

For Chrysler Applications: 45RFE, 545RFE, 65RFE, 66RFE, 68RFE:

Transtar Cleaning Products

Keep hardworking trucks on the road with the Sonnax Smart-Tech® overdrive clutch housing kit (Part #: S72961STK). The unique billet aluminum housing holds a physically taller clutch pack and increases OD apply area by 16%. Plus, 2-times thicker clutches increase clutch pack steel mass by 28% for unrivaled heat dissipation. (Learn More)
This groundbreaking new kit is the only top-of-the-line upgrade that eliminates clutch problems without relying on valve body/pump modifications or adding the expense of extra components. 
  • Modified housing holds physically larger clutch pack for 20% more clutch capacity
  • 2X Thicker steels and double-sided clutches increase steel mass by 28% for unrivaled heat dissipation.
  • Bolt-on anchor plate eliminates clutch pack flexing and distortion that contribute to heat build-up.
  • 16% More OD apply area for firmer, more controlled shifts.
  • Combine with Sonnax line pressure booster kit for even higher levels of performance.



  • Beginning March 1, 2019 Sonnax will stop inserting instructions into their packaging of approximately 1,000 products.

    This change will primarily impact parts such as end plugs, valve kits and bushings that come in small bags. In general, instructions will continue to ship with larger components and boxed products such as Zip Kits® and The Sure Cure® kits.

    Instructions for all products will remain available on the Sonnax website. To ensure everyone has quick access to those documents, Sonnax created a simple search tool found at

  • The housing kit comes with overdrive clutches and steels.
    The rebuilder must supply all other clutches (underdrive and reverse).

  • There is an adapter sleeve that is installed onto the OE inner retainer housing using common shop tools and the chisel provided in the kit. Otherwise, the unit can be built with normal build procedures.

  • Yes, however the most consistent results are from a basically stock overhaul with the Smart-Tech kit combined with Sonnax line pressure booster kit.

  • This kit is currently the best option for increasing the overdrive clutch durability.
    Trucks pulling heavy loads or boosted to 400–600HP are at high risk for burnup.

  • This kit requires use of the input clutch retainer found in '07-later units. All 68RFE, 66RFE, 65RFE should have this retainer. For 45RFE and 545RFE '99-'06 applications, the input clutch retainer must be replaced with '07-later version.

  • This Sonnax Kit comes with:
    - Overdrive/Reverse Housing
    - Bolt-On Anchor Plate
    - Anchor Plate Shims (2)
    - UD/OD Reaction Plate
    - Adapter Sleeve
    - Lip Seal
    - Friction Clutch Plates (6)
    - Steel Clutch Plates (5)
    - Screws (12)
    - Chisel