Help identifying drivetrain noise?

[Jaehead]

So.. the car developed this noise out of the blue. Anybody here familiar with this kind of noise? What is the likely culprit?

[ame]

Here are the facts:

- 37k miles, OEM clutch, procharger car between 550-600 whp
- Clutch does not slip at WOT
- All gears are harder to engage
- 'Hissing' noise when in gear / engaging gear with clutch depressed
- Putting the car back in neutral makes the hissing noise wind down
- Putting the car in neutral + letting the clutch out immediately stops the noise
- No difference in feel in the clutch pedal, and still goes down smooth
- No noise when pushing the clutch in with the car in neutral


Doesn't seem like synchros to me, at least I hope not.. Pretty unlikely at all 6 synchros would go out. Could a worn clutch still not slip under WOT? I did notice clutch slip after doing some back to back 1/4 passes last year. Never noticed any slip during daily driving / autocross though.

TO bearing? but if that was the case I'd expect the noise to be clutch dependent instead of only when trying to engage a gear.

Pressure plate? Although I would imagine broken teeth would be noticed in the clutch travel / feel while driving.

Appreciate any input!

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[moffetts]

Throwout bearing / slave cylinder, most likely. If that’s the case, it’ll operate normally (more or less) for a while and then it will fail completely and the engagement will be on the floor. This is not a fun fix because you have to drop the transmission to get to it. If the TOB fails and sprays fluid inside the bellhousing, you’re going to be in it for a clutch, too.