Sticky: 370Z Transmission Failures (6MT)

Originally Posted by DIGItonium

Replacement #1 (05/18/2012)
I started having 3rd gear grind that progressively got worse. It would be fine early in the morning, and then it would grind above 3k RPM. As it got worse, it grinded all the time. Also, the high RPM 1st to 2nd shift and 2nd to 3rd would grind or lock me out. Gearbox was pretty notchy as well. The transmission was replaced along with a new ceramic clutch disk, master cylinder, and a revised HD CSC.

Replacement #2 (08/30/2012)
A month after the replacement I notice 5th gear was a bit difficult to get into half the time regardless of load or RPM. I thought it was normal notchiness, which is nowhere near as bad as the original transmission (all other gears are smooth). Interesting enough, SynchroRev would rev up twice before I was able to get into the gate. The summer has been pretty hot so I've not driven hard as often, nor have I been out to the strip. There were times it wanted to pop out of gear. Then 2nd started grinding and locking out at high revs. I replaced the fluid with Redline, and it smoothed out the gearbox nicely. However, it didn't help with the occasional 2nd gear grind at high revs or 5th gear lock out. Although it never grinded, the 5th gear lockout was getting worse. My tech took it out last week for a test drive and freaked out when he had trouble down shifting into 5th while exiting the freeway. He couldn't force it in at all as if the synchros weren't there, so a new transmission is on order for this week.

I also went ahead and ordered Motul and Redline fluid for the clutch and gearbox.

[Update] New transmission installed with fluids. This gearbox feels very different. It is not notchy, but there is more resistance and you can feel the gears. There is slight whine in 2nd. Although I am able to shift well now, I miss the buttery ease of the last transmission. I'm going to let it break in and see how it goes from there. part number is the same.

Originally Posted by 370fan

So it lasted 3 years in stock form and 4 months after you put in the new fluids and clutch and HD CSC? Sounds like keeping a stock trans and fluid in there would be the best right??