Dealer replaced the clutch fluid and all is back to normal (for now). I am not going to invest in an aftermarket clutch at 2000 miles, if that's the resolution then Nissan can have this car back. Also asked the service tech to check for the spring spacers and sure enough he handed them to me when I picked the car up. Can't wait to track her again without these!

Clutch failure back brief
 

Just got the back brief from folks at the dealership and they, in conjunction with Nissan regional I suppose, have decided to replace both master and slave cylinders. They said they found air in the system which caused the pedal to go limp at higher speeds/gears and once the air expanded it became an issue in the lower gears as well. That's my take on how they described it. Rather than guess which was the culprit that was allowing air in the system, they're replacing both. And that, my friends, is exactly what I thought they'd do prior to engaging.

Let's hope this is the last go around.

As a side note, I posed my earlier forum query to the mechanics at the dealership as well, I.E. "Why no stable final fix for such clutch failures." And they said the parts involved may have been upgraded along the way to compensate for earlier versions that had issues, but that they weren't always notified of such upgrades. That they would not have access to the older version of, say, the master cylinder and/or slave cylinder and would have to use the upgrade. I hope that makes sense.

We'll see, I get the car back tomorrow and will immediately take it out o' town to see how it responds in fifth and sixth gear.

This has not happened to me yet, but from reading the posts on this thread this seems to be some kind of heat issue more than anything else. I've noticed a lot of failures have been happening after long road trips on the highway, so it does not make sense that a clutch component is failing after periods of non use.

I'm not too familiar how the hydraulic system works for the clutch pedal, so my hypothesis is based on some assumptions. I wonder if driving without engaging the clutch pedal for long periods of time is causing clutch fluid to boil in certain sections since the fluid is stagnant. Perhaps shifting back and forth between 5th and 6th every few miles would alleviate this problem. Or if the fluid does circulate all the time, maybe there is some design flaw where heat is generated and not dissipated properly when cruising for long periods. I've never heard of other transmissions requiring DOT4 clutch fluid for light street use.

I think replacing the master and slave cylinders is just putting a bandaid on the problem. The real problem is what is causing the fluid to get so hot on the highway. Once we figure that out we can find a real solution. I read in other articles that it was easy to boil the brake fluid as well which is why they switched to DOT 4 in the Nismos. This may simply not be enough venting going on in these cars.

^^^You may have a point, the CSC is made of plastic components and known to fail early. zSpeed has aluminum replacements.

Correct me if I'm wrong, but don't the OEM and ZSpeed both have a plastic bellows that travels up and down, and don't they both have O-Ring seals that travel the length of the CSC body/sleeve? So if only the base of the OEM CSC is plastic, and that doesn't fail, but the O-Rings in the sleeve go out, maybe there is something different about the ZSpeed other than not having a plastic base?
I'm not doubting the superiority of the ZSpeed CSC but is there reasonable evidence of the OEM unit failing solely because of the plastic base? All of the failed CSC's I've read about here are due to O-Ring failure and leakage. The photos I've seen of the OEM CSC show metal components (bearing, sleeve, etc.), not plastic.

Same problem as everyone else. The dealer said it will cost $3-4k to replace the csc and clutch.

Sticky: 370Z Clutch Pressure (CSC) Failures
 

Sorry if I missed this but every now and then my clutch is almost empty feeling for the first few inches with zero engagement until it's closer to the floor board but after driving it ANC pumping it a bunch it stiffens up again. Been happening more frequently. I have a 2011 with 35k miles. Think this could have something to do with the master cylinder or the CSC?

Also it normally happens after the car has been sitting for a couple hours. But doesn't do it every time.

You need to replace the fluid and bleed the clutch b/c you have some air in it.

I just had a shop do that though they replaced the fluid in the diff and the trani. U think they messed it up?

No it sounds like there is a little air left in it,or a bad MCS

Most likely a bad master cylinder, becoming pretty common

Is that what u think is wrong with mine joe?

Yes

This is a common problem.... a very OLD common problem.

Hmm guess ill have the dealership look at it since I have it under warranty still. Thanks