DRUM, AODE/4R70W/4R75W,4R70E FORWARD INPUT, 1992-UP FORGED ONE-PIECE, HEAVY DUTY
#76654-01K. Smart Tech 4R70W Forward Input Drum. A common failure of the 4R70W, 4R70E, 4R75W, 4R75E is the separation of the forward drum at the snap ring groove. The manufacturing process of the OE snap ring groove creates high-stress points around the circumference of the drum. The forward drum is active in 1st, 2nd and 3rd gear ranges and suffers the most abuse on a forced 4-3 kick down, especially in heavy duty applications.
The concurrent pressure from the forward clutch piston combined with the high stress at the snap ring groove causes the upper portion of the drum to split and separate at the groove. Depending on severity of breach, this can result in no forward engagement or slipping in 1st, 2nd and 3rd gear. The forged, one-piece construction of the Sonnax Smart-Tech forward clutch drum 76654-01K eliminates weakness at these stress points.
- Increased groove depth for additional ring support
- One-piece forged material provides increased strength and durability over the OE stamped drum