So replaced just the clutch disc today, flywheel, and pressure plate were great condition. Put it all back together, and now the car won't go into any gear. Clutch fully pressed and nothing. We put it in gear, started it, and it started moving meaning clutch isn't disengaging fully. We looked a million times at the fork, bearing, and pedal adjustment between master-cylinder and rod. And still nothing. The mechanic said its most likely the slave cylinder because he said the piston shouldn't be that easy to press in with one finger. I'm on the fence about both slave cylinder and clutch fork because the fork has like half-inch of play back and fourth. But idk, suggestions? Bought a slave cylinder, replacing it tomorrow and seeing if that's the fix

 

Air in the line. Bleed it again.

 

I thought that, but we never removed the slave cylinder just tied it around something. So no fluid ever leaked or anything. We are replacing the slave cylinder, re-bleed, and see if that fixes it.

 

Bleeding it is free, I would do that before replacing the slave. The Master and slave cylinder in the S2000 are quite reliable. They tend to leak but they still work. With the slave cylinder removed from the trans the piston would fully extend inside making it possible for air to make its way in. It worked before you swapped the clutch disc right? Parts rarely go bad while not being used...

 

Disc in right?

 

So, a new slave was not it. Still scratching our heads here. Transmission is coming off again

 

I had that exact problem when my s2000's brake fluid in the master cylinder randomly drained out; the transmission shop wanted $500 for a new master/slave non-oem and filled it up for free. Never leaked a drop.
It was my first manual so I had no clue what was wrong and it scared me. I would be at a stop light pushing full force to the ground and engaging first gear still.
Based on that I would also think it's a fluid issue, but I'm not very educated on the mechanical aspects of what else could be wrong.

 

Clutch has been bled, slave replaced, and master inspected, not seeing anything