So last night, at a light while trying to shift into first to get going, my clutch oedal suddenly sank to the floor and just stayed there solid. Any ideas what it is, and how cost would be for labor

 

jack up the car, have someone inspect the pedal assembly and if okay; have them play with the clutch pedal with their hand I would look thru the inspection whole in the bell housing to make sure the clutch/tob is fine, if thats fine and want to quickly eliminate all possible problems, buy a new slave cylinder(oem), a new clutch master cylinder and a brand new straight steel braided high quality cutch line straight from cylinder to slave, more than likely you have a leak somewhere and better and safer to just replace what i mentioned above, wouldn't hurt to re-bleed but if all of a sudden lost pressure might as well just replace everything at once and stop wasting time, if that doesn't do it and you are sure the clutch/tob/fork/ fork springs is fine then you have a booster problem.

 

What holds the pedal up is the pressure plate. So, most likely the TOB popped out. You should be able to tell just by looking at the outside end of the throw out arm. It will be all the way forward. You can try to pop it back in. I never heard of this being successful but worth a try.

If this is the problem (broken throw out arms are rare) then the price of pulling the transmission $600 - 800 plus fluids plus monoloc plus a new clutch disc (anytime the transmission is out I think it is a good idea to at least replace the disc). A new TOB is a good idea too.

When running a very heavy clutch I've heard of cracked or broken bell housings - also rare.

 

When I had this issue it was the master cylinder costed me $250 with labor

 

Either master cylinder or slave cylinder.

Can also be the throw out bearing. Our clutches are pull style and use a clip to hold bearing to pressure plate. If it pops off. The trans likely needs to be removed and a act monoloc installed. If high mileage might as well do clutch job.

 

Like 4b11slayer said, it seems like a TOB issue. Which clutch do you have in the car?

It was a nightmare with my Exedy twin, happened to me twice before finally giving up and installing an ACT monoloc. Never had that problem since.