I highly doubt a bad clutch would not let you go gear. Your problem is disengagement not a lack of friction. did this problem appear right after changing your clutch? Is the 240 clutch vacuum assisted (my 300zxtt is) My guess is that if you have changed both the master and slave then either the system is not completely bled (which is an incredible pain in the ass...does the 240 have just one bleed point or 2 like the 300?) or your pedal itself may be misadjusted and not actually pushing the clutch far enough away from the pressure plate.