my 05 G35 with 98k miles started making clacking noise all of a sudden

From what you describe Brandon, it sounds like (And when I say 'sounds like' is just a figure of speech. I don't know what it really sounds like) .... You may have a plethora of problems from just a throwout bearing to an internal engine problem. What is curious to me is that you say 'after a couple of minutes'. .... which cuts Way down on internal engine issues. I am leaning to throwout bearing, and at 98,000 miles.... and your wording can be confused... does it begin to 'clack' before you ever push clutch pedal? Or Not? That makes an entirely different situation. Bottom line, I go back to throwout bearing, which means a new disc, pressure plate. pilot bearing at that mileage. A good thing to see is: (click image for full screen) http://forums.nicoclub.com/2003-2007-g35-clutch-replacement-t409693.html

once the clacking starts it stays but it the clacking as i drive will get louder or kinda fade away it happens during the first sendcond and third gear.. when im picking up speed from rev 1 to 3 usually no noise or very quite once it hits rev 3 it comes on usually at this point i throw in a new gear when i press the clutch the whinding noise really comes up when i release clutchs it fades agian and repeats when i put other gears