Why do I hear a whining sound?
 

Whenever I accelerate hard in 2nd or 3rd gear, I hear this whining sound coming from the back. I can't pinpoint it exactly unfortunately.

I know it's not the ECM because I got that replaced under warranty a long time ago and it's silent in the cabin when there is no music on. It's something mechanical. I've replaced the transmission and diff fluid to redline but this noise is relatively new.

Any ideas?

Thanks

Check the hooker in the back, make sure she isn't whining

It's been a couple of hours and none of the experts have answered, so here's my $0.02 worth. Maybe someone with more knowledge will chime in soon.

Did the whine start shortly after changing the diff fluid? If so, I would suspect that the Redline is "thinner" than what you had before. Especially if it is more pronounced once the diff warms up. Whether that's good, bad, or indifferent, I dunno.

Have to agree with South. Whine from the rear end has always been gear related for me, especially if I switched to a lighter gear oil after a ring and pinion swap. It's like the whine you get by switching from timing chains to timing gears, just not as pronounced.

Check this thread. Not sure if this is what you are experiencing..
http://www.the370z.com/nissan-370z-g...-throttle.html