S2 won't shift
 

I also posted this on Rennlist:

It started when I was passing someone, was harder than normal to get into 3rd or 4th. That night it wouldn't go into any gear so I had to put it in 1st THEN start it to limp home. Then it got worse when I got home, when I'd start it in 1st it would start moving like an automatic. I bled the system repeatedly, the slave is pushing the fork just as it should. Pressure plate bolts are good. After bleeding it it just got worse. Now the clutch is completely worthless, you can move the shifter freely without it, you just sit there idling, but the slave is still moving the fork just fine. The pedal assembly is fine. The slave was replaced in December, the clutch is kevlar and was replaced 4 years ago. Also, idling was kinda rough when starting, it didn't want to stay on. And there's red dust all in the clutch housing. It's a pretty good amount too. Thoughts?

This sounds like the clutch or throw out bearing has gone. It's dragging the engine down and That's the first place I'd go. Big job but it sure sounds like where you're headed.

Is the transmission actually shifting? Or did the linkage come unhooked?

You put it in first, rev it up and the car moves? I had a 66 Pontiac Lemans that did that when the clutch disc was severely toasted - you put it in gear, rev like crazy, then the car would finally start to move after a minute (maybe as the metal heated up? Poor car!).

If with the car in neutral, you try to shift into gear, does it grind?

You can measure clutch disc life looking through the inspection port. A new disc, the travel (on the clutch release fork) will be 18mm. If it's more than 34mm, time to replace. Checking Clutch Disc Wear

If you have proper travel and it still grinds when you try to put it in gear, another scenario is the throw-out bearing could have come loose from the pressure plate fingers (the circlips came off and the bearing isn't pushing anything [or does it pull? I can't remember]).

Sorry, was moving across town and got sidetracked. Anyway, it started as hard to get into 3rd and 4th. Then I couldn't get into any gear unless I put it in gear THEN started the car, and then it would creep forward like it was in Drive or something. After bleeding the clutch it won't go into any gear, shifter moves all around but nothing, no clutch, just a free moving shifter. Whole assembly was just put back together in December and I can see the bearing moving, would it really come loose that quick? The clutch is pretty new.

I was told that if the edges of the clutch fork have worn down then the clutch could've been engaged for the past few months without me knowing...I guess that might explain the slight squeal I'd been hearing, when I tapped the clutch like literally a 2mm the squeal would stop. It was pretty quiet though.

Does it sound like the shift linkage?

I guess what I'm really asking, is there anything I can check before I go through the pain of dropping the transmission and sliding back the torque tube? I'll measure the clutch fork movement tonight. But given all the chaos that's going on with the move and 3 broken Porsches with both my dad and I relying on a Nissan with 150k+ miles, I'd like to check all the easy stuff while we're still sorting out the new garage!

Also forgot to add: yesterday we were pushing it in the driveway to maneuver it around and it was making kind of a high pitch quiet thunking nose. Kind of like a creeking.

You need to do a lot more diagnosis.

1 figure out if you are actually shifting in to gear (is the shifter linage still attached and working courtly.

2. Have a friend push the clutch in with you looking through the observation whole and see what you can see. You will want to see if the clutch is disengaging and or that the slave cylinder is working. IF it is then you have to assume that there is something wring with the clutch its self.

It could be as simple as a master or slave cylinder has failed. It could be the through out bearing. It could be the bearing in the crank shaft has frozen to the impeller shaft or it could be a complete clutch failure and something is jamming between the flywheel and the clutch disk and or the pressure plate.

slave cylinder is brand new and working correctly. There is movement of the clutch fork with the throwout moving as well. I think the clutch was originally not engaging because I had to have the car off to get it in gear, but now I think it's constantly engaged because it started creeping forward and now is completely useless. Move the shifter all over the place without the clutch and nothing happens. It's like the clutch is constantly engaged and won't let out because I just sit there idling (and venting about the Germans' ability to constantly drain my bank account).

Here's the list of new/replaced parts:

Kevlar racing clutch-4 years ago
throwout bearing-4 years ago
pressure plate-4 years ago
slave cylinder-5 months ago
all this crap reinstalled with my engine swap 5 months ago as well.

I was hoping it'd be something more simple like the shift linkage, because that I know is 23 years old. But I have no idea what I'd be looking for when I check it, or if that's even it. Because I could get it in gear when the car was off I wasn't sure if it was the linkage because I would've thought that if it was that it would've given out all at once instead of taking a whole evening. The major damage happened pretty much suddenly trying to back out of a parking lot.

I concur with your diagnoses. For some reason the clutch is not releasing. I hate to say it but I think it is time to take it apart. Sounds like something has gone wrong with the clutch. I have seen several "new" ones fail rather spectacularly in the last year.