Noticed if Im driving car pretty hard then it takes a second or so before I can get into 2nd and 3rd gear (even then it can be longer) - sometimes it crunches even with clutch fully in.

Heartstopping moment when I was overtaking a car, knew I had the power but when I was level I tried to get it into 3rd gear and couldnt get it in, couldnt get it into seconds either and another car was coming tomwards me. Crunched hard into 3rd and pulled in front.

 

Sound like a synchro prob?

Possibly low on gearbox fluid?

 

Please tell me I dont need a new gearbox.

you pretty much answered your question mate..

 

try changing the oil first, see if that changes things, if not then a safe bet the syncro has gone, but oil change could be the answer, though yours sounds a bit more serious than the normal mate

Much would a new manual gearbox cost to be fitted? Would the clutch get changed at the same time?

Similar problems to me :- http://www.300zx.co.uk/forums/showthread.php?t=74848

fook me - its been absolutely fine tonight.

Quick changes up and down - no noises no crunch.

I may check gearbox oil levels.

 

Cheers