Well - I've been trying to identify a high speed vibration since I got the car almost one year ago....wheels were balanced (2x - road force balance, etc, etc). Then the dealer adjusted the steering rack - I hate that - removed all road feel. I want that reversed now that we know the root cause of the vibration...

Took it to a different dealership to give them a shot at identifying it. Took them all of @15 min. After a short drive, the tech stated he could feel the vibration in the seat, not steering. He put the car on the lift - put it in drive - and viola! You can see the front driveshaft hopping up and down about 1/2". (I didn't know we had a 2 piece driveshaft) This was a low speed - and you could tell it was out of balance. It is either out of balance, out of round, out of something - don't care, it needs to be replaced.

Taking it back to original dealer tomorrow. (dealer who identified it was not an Infiniti dealer, but one that I had worked with for years prior to going to Inifiniti - he did not charge me for the analysis - GREAT people!).

I will update after this gets settled...

 

Very odd. It must be pretty rare, yours must be the odd defect. Good that you had someone knowledgeable that knew how to easily diagnose it.

 

Yes - both dealerships stated they had not seen that issue before. I am just so very glad it is diagnosed....

 

I have high speed vibration too, esecially when I gently let off the gas or start going slightly downhill. I saved the OP's post to show my dealer when they try to blame it on the flux capacitor or the blinker fluid.

 

^this! lol I'm curious to see the outcome of both your results. I too noticed some vibrations while driving today, I could just need an alignment but still curious what happens.

 

I've been having a similar issue as well...same things done as was to yours and its still there. It's most noticeable between 55-80 mph.

Please keep us updated...

 

New Driveshaft ordered by Dealer. I should get the car back tomorrow or Wed...I will update upon confirmation of fix!

Thanks...

 

see...now i would use this as an excuse to get a new aluminum drive shaft from zspeed.

all the excuse i need anyway....wife is a different story.

 

Yeah - I thought about it - but free is better for now....

 

Update - I got the car back today...

Well that made a HUGE difference to me! Car is smooth now. Feels like I got a new car! Yes yes - I know - this is the way it should have been since day 1...

They also backed off on the adjustment of the steering rack - I got some steering feel back.

It was well worth me pushing to get this figured out...3 trips to the infiniti dealer - and one to my prev Nissan dealership (that actually figured it out )