The South Bend Clutch ISK1.375 is a heavy-duty input shaft upgrade designed to convert your transmission from the factory 1-1/4" input shaft to a stronger 1-3/8" shaft. This upgrade is recommended for high horsepower, heavy towing, and dual disc clutch applications where the stock input shaft becomes a failure point.

As torque levels increase, the factory input shaft can twist or fail under load. The 1.375" input shaft conversion provides increased strength and durability, allowing your clutch and transmission to handle higher power without compromising reliability.

This kit is commonly paired with South Bend dual disc clutch systems and other high-capacity setups where maximum drivetrain strength is required.