I have a loud harmonic humming vibration in my drive line starting near 40mph. It is loudest under load (brake/accel). I have changed all fluids and just replaced the clutch about 1,000mi ago. Fluids are good. Sound seems to come from front and rear... I took it up on stands and drove it up to 40 mph in the air (free wheeling) and heard some metallic rattling sound from the driveshaft and could watch the rear end tweak around, you can see it in below video. I just replaced the front wheel bearings but that wasn't it. I did just eat through a set of rear tires in record time due to a bad alignment and I drive the car hard doing power slides often. I tugged on the DS while at rest and didn't notice what I thought to be excessive play... Could this be bad bushings or something else?

Decel and braking in neutral:
In gear accel and decel humming:
Drivetrain sound:
Driveshaft rotates fine:
Driveshaft during driving:

 

rear diff is dead or transfer case? Might want to look up transfer case death whines and see if yours matches that description.

 

Crap... I think you're right.

 

Damn I hope its not the transfer case. I have this same whining noise.

I hear it mostly on decel from 40-15 mph in neutral, and then cruising on highway in 4th/5th gear at 2250 rpms light throttle.

After watching like every video on the internet on transfer case whines, I feel like its not loud enough to be that (maybe not loud enough yet). but these videos you posted are exactly what it sounds like.

Im only at 40k miles, with normal daily driving, and two light track days.

 

I have hankook rs3 (275's), now that they are half worn they hum like a full blown choir. My previous Ad08 used to sound like stuffed wheel bearings.

Sticky tyres can make all sorts of obnoxious humming and whining noises.

 

definitely not tire noise. Seems to come on with light throttle at specific rpms only. Maybe other times on the gas as well, but the exhaust drowns it out after that.

 

Just as an update, brought my car to Kozmic. Yes, it was the transfer case, and yes it's also the drive shaft. The whine is the TC, typical whine of death. Eric at Kozmic tells me it's from a faulty ACD piston seal that's in pre-2011 TCs. I ordered a used 2013 that they're installing today. They said the screeching/clanging metal sound is my driveshaft and that the 8/9 was more prone to the internal axial sleeve having that issue but is apparently also showing itself on some Xs. I ordered driveshaft bushings to see if that will help. I'll try to report back.

 

sorry to hear.. how much is all this costing you if you dont mind me asking?

 

wow, thanks for the update. How many miles did you have? That literally shot down all my hopes that maybe its not the tcase and maybe its a normal sound.