What is this noise (video inside)

Hey everyone. This is coming from my buddies 300zx nissan. It is a non turbo manual transmission model, 1990. The noise happens in every gear exactly the same, same sound, same volume, etc EXCEPT nuetral. When in nuetral it sounds perfect. He said he changed the clutch and throwout bearing and the noise has not changed.

http://www.youtube.com/watch?v=llCXvj-Pb8c

 

Now that's an interesting one...

So it does it only when in a gear and it does it with the clutch pushed in...yet it doesn't do it in neutral? That's very weird since anything with the clutch pushed in is essentially neutral. The transmission shouldn't know the difference since the engine flywheel hasn't met the clutch disk in any way.

I was going to say it had something to do with the engine harmonics rattling something but since it doesn't do it in neutral that's not it.


What happens when it's at that specific RPM making the noise and you take it out of gear?

 

Is your clutch disc fully releasing?

Try a spindown test. With the car running in neutral, push the clutch pedal all the way down and count to 10secs then shift into Reverse. If there is a clunk or it's hard to shift into reverse then that may narrow your search down.