This transmission friction disc is a wear component inside the gearbox that transmits torque between rotating shafts through controlled friction. It sits between the clutch pack plates in the gearset; when engaged, it locks the corresponding gear to the shaft. A worn disc reduces clamping force, causing slip under load and eventual gear disengagement under heavy torque. The manufacturer machines the disc to the same thickness and tooth profile as the original assembly, so the clutch pack’s spring rate and engagement timing are preserved without shimming. On reinstall, inspect the mating steel plates for glazing and replace the gearbox gasket.