I purchased an 05 G35 Sedan with a manual tranny a few months back.

My concern is about the shifting. It's rough between gears whether flooring it or just Sunday driving. It feels as if the crank shaft and tranny are spinning at different speeds. You can be cruising in 6th and decide to give some gas and let off and feel a buck. The bucking doesn't happen immediately after a decel/accel.. it happens about a half second afterward. When cruising at any speed, pressing the clutch pedal down and removing it quickly results in a banging noise and the car bucking. When cruising at a constant speed, we can just barely give the car some gas for a small acceleration and the tranny will vibrate a few times as if someone were shaking the car from front to back.

We took the car to Infiniti and were told that it's the box. They had to put a beefier box in the manuals due to lots of transmissions failing at a young age on other manual sedans and coupes. Has anyone else heard this story.

Can anyone else confirm for me the rough shifting?