High Speed Vibration
 

Good Morning, new to the thread. I have owned a 2010 G37X from 10 miles on the OD. At 108; fantastic car. I have developed a vibration thru the body/seat at 60+mph (not seen at higher or lower speeds) when I come off the accelerator & coasting. When I hit the accelerator, it immediately goes away.
Here is what I have done:

• Removed weights, scotch brite the inside of the rims, and had M-Defenders (2nd set) put on (Costco tech said, he's never had cleaner, balanced wheels come out).
• Replaced all 4 bearing hubs (front/rear)
• Inner & Outer Tie rods.
• Service Bulletin complied with that checks the Drive Shaft/Propeller
• Replaced all fluids in both diffy's and transfer case (no excessive metal shavings).
• Sway bar links replaced X4
• Upper & lower ball joints and bushings on all 4 wheels appear to be in good shape (haven't changed them yet).
• Drive shaft (propeller) is tight, but haven't disconnected it from Transfer or Diff to see if there is any play.

No vibration in the steering-w or shift handle, when I kick it into neutral, Vibration is still there at 60+ (obviously I'm not dropping the tranny into drive at 60, I've coasted to a stop).
BUT this thing is kicking my tail!

Any help would be appreciated...

Thank you,

Interested in what you find - similar vibration in my AWD that's been there since I purchased August 2017. Seems to be more pronounced on very smooth road such as fresh blacktop but I feel it in the seat and notice as the hood shakes slightly.

-Eric

just a shot in the dark here, but have you looked at your motor/tranny mounts and diff bushing?..it sounds like some slop in the driveline form worn bushings/mounts

I had a similar experience. A road-force balance of all four wheel cured it. Note that Costco doesn't have the machine for road-force wheel balancing.

Also, make sure they check the wheels for trueness; a bent wheel may be the culprit.