Gears are grinding. Don't know if it's syncros
 

For the longest time it's only been my 5th gear if I shift it hard. After a little bit of spirited driving it grinds alittle as I push the clutch in and put in a gear like 2nd and 3rd. And reverse grinds really loud when I'm feathering and releasing the clutch. Horrible sounding. Do I have to re bleed and use better fluid? Idk what to do. It drives fine but grinds slightly when driving. And reverse gear is ear bleeding bad

When was the last time (time and miles) trans fluid was changed? I'd start there. Otherwise, maybe change your shifting technique. Else time for a new trans...

Changed the Trans fluid under 10k miles ago... This morning I turned the car on. And putting the clutch in when in neutral after 30 seconds of the car on its like grinding alittle. And when I throw it in reverse. Forget it. Horrihle sounding. And it's slowly happening in first. And like 2 ND gear. Clutch in. Put in second and grinds a tiny bit. Clutch out grinds a tiny bit

Is the pedal hard almost immediately after depressing or is it soft/mushy? While it's definitely possible to be a trans issue, it's also possible your clutch is not releasing entirely. That is, although pedal is to the floor there is some coupling between the friction disc and engine.

I remember testing driving a G prior to buying mine. This one had an after market clutch which wasn't adjusted correctly. Had a very hard time getting it into gear. It didn't grind though, just wouldn't go into gear.

The pedal is perfect. I have a heavy duty slave cylinder. New master cylinder. New flywheel and clutch kit everything is new 10 k miles ago

Begs the question if the pedal was adjusted properly at the time of clutch change. That is so clutch was fully disengaging. Are you still in warranty/powertrain?

There's a guy on the 370z site selling a new 6mt for ~$1500.

The last time my transmission was changed was monthssss ago. And that's when my whole clutch was changed. And I've put like 10k miles on it and it's fine

What transmission oil did you use?

No clue my one mechanic did it for me. He uses good stuff though. He's that type of guy

Sonic, you think too high viscosity oil or gl5 may have had something to do with this?

Goodstuff != proper oil :)

same here... my G is currently stuck in 5th... bought a replacement because transmission parts are soooooo hard to find....

Yes, something along those lines... The newer manual transmissions require specific transmission oil which has the proper co-efficent of friction and viscosity.

To the OP: I would ask the mechanic if he used Nissan MTF (Manual transmission Fluid) and if not, I would try it. It is the lowest cost next best option.

Good luck!

So about 10k miles ago you had the entire clutch system replaced? From the clutch MC down the to tranny fluid? If so there could be a dozen problems it could be. Did they use a new tranny or a rebuild? If it was a rebuild was it rebuilt by a reputable company? If it was a straight up used tranny then you might be hosed.

At first i was going to say swap the fluid for some you KNOW is correct. The wrong tranny fluid can and has caused gear issues in many different cars. I had an rx8 that had brass syncros and if you put the wrong fluid in it would eat the syncros and ruin the tranny.

Also and please dont take offense but if youre on your second tranny could your driving style be part of the problem? From your explanation it sounds like the issue started small and has been gradually getting worse. Thats telling me theres something wrong thats probably more than just an incompatible fluid.