05 Q intermittent shudders drivetrain-?

[O5Q45]

New 05Q45 owner just joining-
I purchased a 2005 Q in Atlanta GA with 87k on her. Drove 300 miles home no problem. After a week with the car I noticed a vibration in the rear from 65-75 especially if I let off the gas. If cruise is on and I start down hill the car lurches as if tapping the brakes.. but in the drivetrain. But what annoys me greatly is from a dead stop when I take off I feel a shimmy shudder slip but with no loss of power in the rear. If I press the pedal to the floor the car is smooth as silk all the way up the tac. I went to Harper's Infiniti in Knoxville and paid 135$ for a full bumper to bumper inspection and the Sr tech driving the car. I was told everything was excellent all the way down to the wipers. He pulled all the records from Nalley Infiniti in Atlanta. The car has been babied from mile one. Anyone know or has dealt with this shudder at take off? Everyone who rides with me thinks I'm crazy and says they dont feel it... Jeez....

[Q451990]

to NICO!

Isn't it frustrating when you feel a vibration or hear something, and no one else can hear it? I'm that guy too.

Check to see if the shudder is worse from a stop with the car facing uphill. If this was a 90-96 Q and it's worse going uphill - I'd point to the transmission mount (sometimes called the third engine mount) being collapsed. That vibration is usually felt more in the bottom of the seat vs. the rear.

I have no idea if your series of Q has the same setup. Your car's factory service manual is available at http://www.infinitiservicemanual.com if you want to see.

[O5Q45]

Thanks for welcoming me! One other thing I would like to add to the symptoms is that it seems worse after its drove a good while and is hot. Otherwise, that's exactly how it is, worse from a standstill and definitely going uphill. I have every record from day one from Roswell Infiniti in Atlanta. It's definitely been taken care of as far as maintenance schedule but who knows how it was driven. I got this car after we totaled a Ls430 and I'm still getting used to some differences but I know there's something sinister lurking about in the drivetrain just waiting for an opportune time be it middle of intersection or 2 am on the freeway. Seems there's nothing I can do with Infiniti's nothing's wrong prognosis....

[Q451990]

Well, if it should make you feel better that the car is far out of warranty - so they're not intentionally not seeing/feeling an issue.

[O5Q45]

That is a perspective I can live with. I'll carry-on until it's undeniable. I can say I've never enjoyed a car so much. 340 horses is just the right recipe for "get me out of here" 5'o clock traffic. Other than the vibration the car has been turn key ready to go. Thankfully it doesn't burn an ounce of oil, I'm getting 26.3mpg daily on the highway and don't even have to look away from the road with voice controlled climate, radio and nav. The beginning of a beautiful relationship-