Stihl Clutch Spring for 064, 066, MS640, MS650, MS660 Chainsaws 0000 997 0912

OEM Clutch Tensioning Spring from Stihl. Clutch springs loose their tension over time, especially when the clutch drum is heated up. Once they loose their tension, the clutch will always be engaged, even when the saw is at idle, making for an unsafe chainsaw. Clutches usually require 3 springs.