Sonnax Smart-Tech drum module for big main shaft 34555-03K upgrades racing GM TH400 transmissions previously built with Coan Racing XST 1-1/8" main shaft. This unique drum system is proven to improve on-track performance and consistency, leading to quicker ETs, more wins and greater reliability. The big main shaft version features a forward clutch hub, sprag shaft and sprag-shaft-to-center-support-bearing adapter configured to work with the Coan shaft. 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 counter-rotating parts is closer to the centerline, there is a 53% 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. * Kit replaces both forward and direct drums and includes everything from intermediate sprag to the pump, minus frictions and steels* 100% new content, no used core pieces* Includes larger-diameter, 36-element sprag and sprag race that works with OE intermediate clutches

Sonnax 34555-03K Includes:

• Forward Piston Housing
• Forward Piston
• Forward Piston Return Springs 16
• Forward Spring Retainer
• Forward Snap Ring
• O-Ring Small
• Lip Seals 2
• Direct Housing Assembly
• Direct Piston
• Direct Piston Return Springs 26
• Direct Spring Retainer
• Direct Snap Ring
• O-Ring Large
• 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"
• Quad Ring Seals 2
• Anti-Rotation Seal Rings 2
• Drum
• Pressure Plate
• Outer Snap Rings 4
• Bearing 3-Piece
• Forward Clutch Hub
• Bearing
• Direct Clutch Hub
• Clutch Separators 60
• Sprag Shaft To Center Support Bearing Adaptor