About a year ago i had the clutch replaced in my 07 350Z Touring, lately after driving the car for about a 1/2 hour or so the clutch pedal gets very spongy and feels like its not grabbing. All my fluids are good, when the clutch was done the pressure plate, throw out bearing, and slave cylinder were also replaced. Is this possibly a issue with the clutch master cylinder??

 

If you put in a new oem CSC (concentric slave cylinder) and running the act heavy duty clutch like your signature says, then you've likely a popped CSC. A gummed up master could do the same thing but a failed CSC is thr most obvious root cause.

Zspeed a vendor on the forums makes an aftermarket heavy duty csc that 95% of the aftermarket clutches
really require to install on an 07-08 vq35hr Z or G.

Sorry to hear y our havingv issues btw

 

Will this issue involve dropping the tranny again?

 

Unfortunately yes, the CSC is inside the bell housing around the transmissions input shaft.

 

Dropping it off tomorrow to have slave and master cylinder replaced

 

Are you replacing with OEM CSC or zspeed? If oem expect to be doing this again.

 

Wilwood Clutch Master Cylinder and ZSpeed CSC. I decided to just go ahead and do them both, I figured it would make my life a little easier.
Thanks for your help!!

 

I have a very similar issue too with my clutch pedal. Same pedal feel and I've got Competition stage 2 clutch and flywheel with fresh fluids. But mine is '05 and if I remember correctly the '05 doesn't have the CSC (concentric slave cylinder) system? So what do I need to fix?

Edit: Also like OP, my slave cylinder were also replaced because years ago my pedal wouldn't pop back up.