David Bliss
Member
I have heard this sort of chatter. It can be lay shaft chatter, which is caused the gear oil needing changing or being the wrong grade, or by the engine having rough idle. Some gearboxes do this part way through their life, and the problem can disappear only rattling when very hot. Some will chatter when pulling away in 1st gear occasionally. As I haven't heard your rattle it is difficult to be more specific. My wife once rang me and said the car was making a dreadful noise, and she was worried that it might be the gearbox. Turned out the exhaust had fallen off .