Preserving transmission synchros

NismoNY

Anyone?

JARblue

Nissan has a habit of fixing a problem by using slightly less prone to fail parts. I wouldn't be surprised that they 'toughened' up the 5th gear synchro a few times and it's still shitty. That's what happened with the steering lock. They had four revisions before removing it completely in 2012 and later US models. Rev D is the version to be installed via the recall notice, but it had known failures on this forum long before the recall was even issued.

I have a late model 2011 FWIW. 5th and 6th gear synchros both started showing signs of wear under 20K miles. I've just tried to avoid stressing them for the past 40K miles (I'm over 60K now).

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NismoNY

When you say they are showing signs of wear, what are you referring to specifically? Grinding?

JARblue

Yes, grinding. I can grind 5th and 6th gear on demand shifting normally. But with a little bit of patience it does not grind at all - I just hold it at the gate for a moment while the engine RPMs drop.

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NismoNY

It's still unacceptable Nissan can't build a transmission that doesn't grind

wrxrcr

My first to 2nd gear can be a little stiff when cold but after that i have no problems.

Rahul718

I feel shifting slower is better for the synchros. I don't feel that fast shifting every gear is necessarily better for the transmission.

JARblue

Of course slower shifting is going to cause less wear on the synchros. Assuming proper shift timing. I don't think anyone here said that fast shifting is better for the transmission.

My only comment is that fast shifting, when done properly, should not wear out the synchros significantly faster unless you're just ripping through the gears every time you drive. If you drive mostly with casual, patient shifting, then the occasional fast shift at high RPMs should not be causing excessive wear on your synchros.

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jwick

The synchros are crap in 5th and 6th. I had my tranny completely replaced under warranty about 5k miles ago. I really think it's either you get good ones or you don't. Nissan really has a knack of having issues like this with their cars.

No issues with the new tranny but it only has 5k miles on it. Oh and I added 250hp/tq since then so I wouldn't blame the tranny if it craps out on me.

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Rahul718

So... sort of stupid question to ask and it's in line with my OCD about my car...

A while back I swear I was having the same issues as the OP in terms of the SRM acting funny when sometimes up shifting into 5th gear from 4th. I now understand it was driver error as I was hitting the gate of 4th very slightly on my way to 5th.

However, for a period of about 2 weeks I was trying to replicate the issue by up shifting from 4th - 5th between 4-5k rpm continuously all the time, during my commute, during my spirited driving, etc. I must have done a few hundred of these upshifts in that RPM range. However, I was very careful about these upshifts and never shifted hard or too fast. I would go up from 4th, pushed the shifter to the right and up into 5th - I never once diagonally up shifted and always kind of eased it into 5th during these up shifts.

It remains smooth as butter but I can't help but ponder if that did any damage to the synchro but continuously up shifting or if I accelerated any kind of wear. Again, it shifts great for the record.

NismoNY

If you don't experience any grinding now and it's smooth, I can't imagine you didn't anything that accelerated wear. I think it's as simple as that

Shotta

Don't drive around with the weight of your hand or arm constantly resting on the shift lever.

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Rahul718

I hear ya...It's just an uneasy feeling knowing that I possibly accelerated wear on that synchro from the higher rpm (4-5k) shifting

I never heard of this. I thought once the shifter is locked into gear then it wouldn't matter

Cvzg77r

I have a 12 with about 56k miles on it and I had my transmission replaced twice, one for 5th gear and the other for 6th gear. The first time I fought with shop foreman the second time they just put it in there. I'm a senior tech (at lexus so noises bug me a lot) and I was not about to have him tell me its normal lol it happened in 10k-12k mile intervals If i remember right the first one was around 12k and the next one around 22k. I drive the same as I have then and the third transmission has been fine, and recently I've experienced random sticking csc and clutch slippage issues (after shifting to second at times the pedal doesn't come up all the way like as if it looses pressure and the rpms just go to red line and burnt clutch smell comes right after and the pedal is very soft and then it regains pressure. They already bled it and put in gtr fluid as if it would magically solve everything.) Also the way I found my synchros failing was either shifting from 5th to 6th and 6th to 5th.

Shotta

Google "resting hand on shifter" and lots of info will come up. It was one of the first things I was taught when I starting driving manuals 25 years ago and Im pretty sure it still holds true with todays manuals.

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