Manual Transmission Clutch Chatter
Clutch chatter is the initial shudder when a faulty clutch disk or component first engages. This shudder or vibration may vibrate throughout the entire vehicle. It's often the result of worn or contaminated clutch components. As the assembly turns, the clutch disc grabs and releases the flywheel and pressure plate. It happens very quickly as the engine is rotating.
Clutch chatter is different than clutch slippage. Clutch chatter occurs when the clutch is first applied and goes away after the clutch has fully engaged. Clutch slippage is the clutch disk's continued spinning without full engagement.
Faulty dual mass flywheels, worn discs, and over-machined flywheels result in clutch slippage. With clutch chatter, the vehicle shudders and shakes. With clutch slippage, the engine increases in RPM with little change in vehicle speed. Sometimes, the vehicle may not even move forward.
Worn or contaminated clutch facings cause clutch chatter and grabbing. Contaminated clutch disk friction material is typically the result of oil leaking from the rear main seal or front transmission pump seal.