The IAME outer washer is a piece of friction and calibration at the end of crankshaft, just after the needle cage. Its role is fundamental: it ensures axial retention of the clutch bell while protecting the cage needles against lateral pressures.

Machined with a perfect flatness, it allows the bell to rotate freely without excessive play, ensuring that the clutch remains perfectly aligned with the motor output sprocket. A worn or missing washer can cause quick destruction of the needle cage or clutch lock.