TH400 Extreme Duty Forward Drum & 300M Input Shaft 35-Spline

Brand:	Speedmaster
Part Number:	PCE623.1028.01
Part Type:	Automatic Transmission Drum
Transmission Drum Material:	High-strength chromoly steel
Sprag Assembly Included:	No
Quantity:	Sold as a kit.

Take your GM TH400 transmission to the next level with this premium heavy duty forward drum and 300M input shaft combo. Engineered for high-power street, strip, or off-road use, this kit addresses the critical failure points of stock components with a focus on strength, precision, and reduced rotating mass. Heavy Duty Forward DrumConstructed from high-strength chromoly steel – providing exceptional durability without the weaknesses of cast iron or aluminum. Lightweight design – 3 lbs lighter than stock and nearly the same weight as an aluminum drum, without compromising strength. Oversized 28-tooth shaft-to-drum spline – significantly stronger than the factory design, addressing a common failure point. Enhanced clutch engagement – features dual clutch splines (28 vs. 14) for better support of clutch separators. Precision-machined lightening holes – reduce rotating mass and align with input speed sensors in aftermarket cases. Optimized design – includes ribbing and internal diameter reduction at the middle seal area for further weight savings. High-RPM checkball capsule included – prevents pressure drop at 5500+ RPM for consistent clutch performance. No middle seal required – compatible with clutch volume spacer kits if fill/drain time needs adjustment.   300M Extreme Duty Input Shaft Made from ultra-tough 300M steel – heat-treated for exceptional resistance to twist and fracture under extreme torque. 1-1/8" diameter, 35-spline design – the strongest configuration that fits within a stock-style stator tube. 35% stronger than standard 1" shafts – built for serious racing and high-horsepower abuse. Compatible with aftermarket drums using 28-tooth internal spline – ensures secure engagement with heavy duty drum.   Installation Notes: Input shaft requires a 35-spline turbine hub in the torque converter. Must be used with a large-diameter stator support tube.