Sonnax Smart-Tech Drum Modules

Sonnax Smart-Tech drum modules for racing GM TH400 transmissions improve on-track performance and consistency, leading to quicker ETs, more wins, and greater reliability. The TH400 is preferred for its overall durability and multitude of available ratios, but is known to be heavier and less efficient than the popular two-speed Powerglide. Part of the TH400 inefficiency results from the fact that the direct drum counter-rotates, spinning backwards in 1st gear, brakes to a complete stop on the 1-2 shift, then goes from 0 RPM to input RPM on the 2-3 shift. Significant energy is wasted through this cycle that robs power, upsets traction on the shifts, and contributes to broken internal parts.

Compared to aluminum direct drums, the Smart-Tech drum module reduces the weight of the counter-rotating components by over 3.3 lbs.! And more significantly, because the weight of the Sonnax counter-rotating parts is closer to the centerline, there's a 68 percent reduction in energy required to stop and restart during the 1-2 and 2-3 shifts. The benefits are increased wheel horsepower, better acceleration, less shock on the shifts, and improved durability.

* Complete kit (34555-01K) replaces both forward and direct drums and includes everything from intermediate sprag to the pump; a selection of Sonnax input shafts is available separately.
* 100 percent new content, no used core pieces
* Includes larger-diameter, 36-element sprag and sprag race that works with OE intermediate clutches
* Includes six-friction forward clutch pack and seven-friction direct clutch pack

Contents:

* Forward Piston Housing
* Forward Piston
* Forward Piston Return Springs (16)
* Forward Spring Retainer
* Forward Snap Ring
* O-Ring 1.674 in.
* Lip Seals (2)
* Direct Housing Assembly
* Direct Piston
* Direct Piston Return Springs (26)
* Direct Spring Retainer
* Direct Snap Ring
* O-Ring 2.737 in.
* Sprag Shaft
* Front Sprag Retainer Plate
* Heavy-Duty Sprag 36 Element
* Outer Sprag Race
* Rear Sprag Retainer Plate
* Sprag Retainer Screws (4) 6-32 x 5/16 in.
* Quad Ring Seals (2)
* Anti-rotation Seal Rings (2)
* Drum
* Pressure Plate
* Outer Snap Rings (4)
* Bearing Small
* Forward Clutch Hub
* Bearing Large
* Direct Clutch Hub
* Steel Clutch Plates (4) .060 in.
* Steel Clutch Plates (11) .077 in.
* Friction Clutch Plates (13) .080 in.
* Clutch Separators (60) .103 in.


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