Hello fellow Z enjoyers (what a time to be alive with that name huh?)
I wish I could say I am a happy owner of 2004 silver, Swiss-made, manual transmission 350Z but I'd lie. This car means one repair after another. Yet, I love it and we are in some kind of a toxic relationship. No matter how much money, oil and gasoline I feed her she still reaches for more. (+-2 litres of 10w60 per 1000 kilometres, 2004 VQ35DE is a masterpiece indeed)
Recently, I have noticed a strange howling/humming sound coming from the back. It only happens on 2,3,4 and 5th gear at 2500-4000 RPM (Can't really tell if it happens above 4k, because the engine sound overruns everything else at that point).
It goes silent when I release the throttle. The sound is the loudest at around 3k on stable throttle. I have searched the internet but I still don't know where to look for an answer. Some people say it is rear differential wear, some that it is flywheel and some that it is caused by ruined bearings inside the gearbox. I know for a fact that my clutch + flywheel + thrust bearing set is close to death (the clutch is connecting really high and I can hear the characteristic click sound when shifting, and on top of that the car is producing some wheezing sound when on idle, which goes away after I press the clutch). Can any of these parts cause this howling/humming sound when pressing gas?
Has anyone every faced that problem and found a fix? I am just lost and don't know whether it is safe to drive it for now or should I have some mechanic detach and inspect the inside of the gearbox.
I would appreciate any help!
Have a nice day!

 

Wheel bearings?