High Speed Vibration issue
 

I've got a 2007 G35X, and had a G35S rear sway bar installed last week. After the shop installed the sway bar they did a 4 wheel alignment, it was much needed. Everything felt great, noticeable improvement! Up until last night the car felt great. All of a sudden, this morning on my commute to work I started to get a pretty significant vibration around 60mpg+. It seemed to be coming from the rear.

After noticing the vibration, during lunch I had all wheels balanced and rotated. The vibration is slightly better but still noticable at 65mph+ or so. The shop today said they were fairly out of balance, but the tech didn't notice any vibration on the post-balancing test drive up to 75mph and all suspension components looked good.

I think the vibration gets worse the longer your maintain high speed. Thoughts?

I thought a wheel weight may have come off this morning, but after the new balancing I'm still noticing the vibration...

I had a similar problem took almost 6 months and several parts to finally get it , in my case was diff bushings which in turn took out the driveshaft carrier bearing , replaced both No more vibration

I had the same issue I had my diff bushings replaced.

I have a 2010 G37X and have the same vibration at high speeds. Changed several parts, but I am currently stretching and getting ready to change out the Propeller Shaft (rear drive shaft - too much play in the center bearing) and oh yeah, all three bushings on the rear differential. I am expecting the same outcome!

Well, hope like a Jedi.....