I have just developed a strange sound when I start up. Doesn't happen all the time but usually after I have taken ot out for a ride, parked and started back up after 5 mins or so.

It soulds like a "metalic" on "metalic" sound. It is comming from the center area of the car. It doen't matter if the clutch is in or out in neutral. Usually, after I put it into gear it goes away. Drives fine, shifts fine at a stand-still when waiting, no noise.
Almost like a rattle...I can hear it for a few seconds when I do over some bumps. When it is happening, I rev it a little and it stil happens but then suddenly stops.

Strange.
Apx. 6,100miles

Any Ideas????

 

Same thing????

https://my350z.com/forum/maintenance-and-repair/45812-grinding-noise-at-start-up.html