How does the clutch system on my nitro model work?
The clutch system on your model is a centrifugal clutch. When the engine is sitting at idle, the clutch shoes, which are held together with a clutch spring, contract around the crankshaft and do not touch the clutch bell. As the engine rotates faster the centrifugal force overcomes the spring and causes the clutch shoes to expand, which engages the clutch bell. If the clutch spring is broken, worn or stretched, then the clutch shoes would be allowed to expand and engage the clutch bell at all times, no matter how low the idle is set.