I've been around the forums forever without contributing, but having seen all the threads regarding clutch judder, misfire codes, and being "locked out" of first gear, I think my experience could be useful to others.
Bought my Z used about 2 years ago and it always had these problems:
1. Starting out in first gear it felt like the clutch was either massively slipping or something was shaking. This would only happen about 50% of the time.
http://www.the370z.com/nissan-370z-g...-common-2.html
2. About once a week I would be stopped at a light and when I was about to start moving I would push the clutch all the way in, but I could not shift into first gear. A quick clutch in/out would allow me to get into gear.
Can't get in first gear
3. On a regular 4-5 month or so basis, I would get a p0300 code, but nothing ever seemed wrong with the car so I would just clear it and move on.
Engine problem - p0300 - Whats the fix?
These things bothered me, but they were intermittent and small enough that I got used to them. My old 350z had many of the same issues so I thought it was normal. Many of the posts regarding judder are answered that is it IS normal.
After 3 weeks of struggling to fix a persistent p0300 code, Nissan finally replaced my flywheel. The code hasn't been back since, the clutch judder is 100% gone and I am never locked out of first gear! As the driver, the car feels SOO much smoother.
Now that I look back, the solutions seems obvious for the symptoms I was experiencing.
To those who have wondered why its so difficult to engage the clutch in first properly, it may not be driver error!
Hope this is helpful, sorry if this is the wrong section.