Thanks for any input. I have a 2008 G35 RWD with 128,000 miles on it so I know the car will have its problems. Up until now the car has been mechanically flawless, I have regularly maintained it, used only premium oils/gas, refrained from punching it around every corner and so on. When I am accelerating I am getting some vibration. It is somewhat in the steering wheel but it feels like it is coming from the rear. I know it is not tire slip. It occurs around 2-3K RPM at 35-45 ish MPH. I am not sure what gear it is, but when I am on the highway I have absolutely no vibration outside of the ranges described. I think it is either the transmission or the driveshaft... what do you all think?

 

Is it speed sensitive or rpm sensitive? Or does it only happen when the RPM is at that range AND at that speed? If you can get the car vibrating, if you shift up or down does the vibration change?

 

I probably should have checked the gear it was in when it does this before posting. Its pretty much when it is both the RPM and MPH range that it occurs. It will happen pretty much regardless of gear and will continue until I go above or below that range.

 

Clean your throttle body.. Happened on my old man car at RPM 2k - 2.5k.. GL

 

i would check your driveshaft flex disc for cracking where the driveshaft or yoke bolts the flex disc together.

 

Check motor and trans mounts