SKU: COA22815
MPN: COA-22815
The COAN Aluminum Direct Drum Assembly 7075 Billet Aluminum (COA-22815) is a high-performance transmission component engineered for serious TH400 transmission builds. This direct drum serves as the 5-clutch intermediate hub and pressure plate, built from aerospace-grade 7075 billet aluminum for maximum strength-to-weight ratio. The direct drum is the critical rotating element that engages the direct/overdrive clutch pack, making its material composition and precision engineering essential to reliable power transfer in high-horsepower applications.
Weighing 9.14 lbs, this billet aluminum construction reduces rotating mass compared to cast iron alternatives while maintaining the structural integrity required for sustained high-load operation. The 7075 aluminum alloy is recognized in automotive racing circles for superior durability and fatigue resistance. The drum's 5-clutch design accommodates the friction material stack needed for aggressive lockup characteristics typical of competition transmissions. This assembly integrates the hub and pressure plate into a single precision-machined unit, simplifying installation while ensuring precise clutch engagement during gear transitions.
Builders upgrading TH400 transmissions for street performance, bracket racing, or power-adder applications rely on direct drum quality to handle increased torque multiplication through the converter and planetary gear sets. The direct drum's condition directly affects shift feel, converter efficiency, and overall transmission reliability under load. This billet aluminum design is preferred by transmission shops targeting repeatable shift quality and extended service life in modified applications.
The TH400 transmission has remained a platform of choice for performance builds since its introduction, and quality component selection—particularly in core elements like the direct drum—distinguishes a stable, predictable transmission from one prone to slippage or failure. This direct drum assembly represents a foundational upgrade for any serious TH400 rebuild.
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