This friction disc sits inside the gearbox and is the component that transmits torque between rotating shafts during a gear change. It is the element that is squeezed by the clutch pack to lock the selected gear ratio, enabling smooth engagement without grinding. When the friction material on the disc wears thin, the clutch pack loses clamping force, resulting in gear slip or difficult shifting. The disc is manufactured with the correct tooth count and thickness to match the original assembly's stack height, so the clutch pack's clamping load and release clearance are preserved without additional shimming. On reinstall, ensure the disc is free of oil and that the hub splines align freely with the mating shaft before torquing the clutch-pack retaining nut to specification.