Preserving transmission synchros

NismoNY

Is high rpm shifting necessarily bad for synchros even if it was done carefully and gently (not slamming gears and letting the shifter slide into place)?

JARblue

I would say there is nothing gentle about my high RPM shifting. But if done properly, the excess wear is minimized. Hard shifting at high RPMs is always going to wear on the synchros more than normal, casual shifting. But it shouldn't significantly decrease the life of the synchros unless you just do it all the time or do it improperly.

Even though I clearly have some synchros that are wearing as indicated by my grinding when upshifting from 4th to 6th, I have never experienced grinding on a hard sequential shift at high RPMs.

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2011 Nismo#91

You'll be fine, quick drastic changes do the most harm. High rpms put a lot of stress on everything, not just your transmission. But, plenty of people track this car getting it close to or at redline often under high load and still have their engine running fine for years now. You can change the fluid the Redline MT-85 or similar if you want the added piece of mind or feel you have similar issues to what people described above.

DIY: Transmission Oil Change

NismoNY

Came across 2 posts mentioning Nissan upgraded the 5th gear synchros in the later model Zs. Is this true?

2013 Nissan 370z

Sticky: 370Z Transmission Failures (6MT)
"Well known that the Z has crappy synchros.

They toughened up the 5th gear synchro in mid10 and again in early 11. By all measures the mid11s seem to have dramatically better 5th gear behavior."