Sonnax®

TH400 Drum

Smart-Tech® High Performance Racing Module

GM Chevy Buick Oldsmobile Pontiac

1964-1992

 

For racing applications that do not use front band and run a 1" main shaft.

 

Sonnax® Smart-Tech® drum module 34555-01K for racing GM TH400 transmissions improves 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 1^st 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 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.

Complete kit 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% 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 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 Small

Forward Clutch Hub

Bearing Large

Direct Clutch Hub

Steel Clutch Plates (4) .060"

Steel Clutch Plates (11) .077"

Friction Clutch Plates (13) .080"

Clutch Separators (60) .103"