looks like the wheels gonna have to wait...

 

Thinking about getting this, I doubt it will fix with my 5-6 shift grind/bite.. but hope it will help.

 

The only thing that can settle down catchy syncros is to stabilize the transmission. In our cars, that means an aftermarket transmission mount and/or engine mounts.

I had the infamous 5.5 Gen Maxima "3rd Gear Crunch", which all but went away after swapping in solid poly engine mounts.

 

Thanks bud, I'm taking a screen shot of the reply so I remember that. honestly I have no clue what a "solid poly engine mount" is, time for some research I guess!

 

My best not-a-mechanic explanation:

Engines rock along their axis. And the engine is connected to the frame of the car by engine mounts, which contain bushings that act as dampers to that rocking motion. The softer that damping process, the smoother the car feels. The more stiff that damping process, the more rough the car feels. By reducing the damping, you transmit more energy through the drive train. Energy that would otherwise be wasted as kinetic energy.

In the Maxima, you could cut out (or burn) the bushings inside those mounts, and press in new aftermarket bushings made of solid polyurethane. For the G37, you can replace the mounts entirely with aftermarket devices. I know that Z1 Motorsports sells a pair, for $200.

Similarly, there is a single mount between the frame of our car and the transmission casing. Z1 makes an aftermarket tranny mount, too (for the RWD only). 4DRZ had one swapped into his 6MT Sedan a few months ago. I've got one sitting in a box in the corner of my office, scheduled for a May install.

If someone wants to explain this better, please do. That's my best shot.

 

That actually makes me understand why this is happening a bit better. I will ask Sasha from boosted performance, if I go see him, If he can help me out with this.

Or maybe I'll get the stuff from the states... If our dollar keeps goin up lol (CAD vs USD)

 

I don't think a stiffer rear mount will help the reduce the 5-6 grinding.

On the G37, the shifter is mounted directly to the transmission, so the movement of the engine/transmission does not interfere with gear selection.

On the Maxima, the shifter is mounted to the body. The movement of the engine/transmission can interfere with gear selection. Reducing the engine/transmission movement by using stiffer mounts can help.

Also, the G37 transmission mount is a single point:


If our transmission had two mounting points (like most) then a stiffer mount would reduction the movement. Since our cars only have ONE transmission mount, a stiffer transmission mount will only allow more vibration into the interior.

 

It's the gear change that's problematic, irrespective of the mechanics that initiated that gear change. Plus, the Maxima was a cable-shifter, further removing the relationship between shifter and actual gear change. Stabilizing the engine/tranny reduced the problem with the syncros in that car, because that's where the problem was, not in the shifter itself.

I'm fairly confident that stiffer mounts (tranny and engine mounts both) will make gear shifts smoother in any car, with the obvious trade-off in added NVH. I will certainly have a hands-on opinion about the Z1 Tranny mount one way or the other in a couple months. 4DRZ already has that opinion, and is pretty solid (no pun).

However, if all the new tranny mount does for me is introduce unwelcome cabin vibration without any other benefits... well, then I suppose I'll be pretty bummed out. Might even have the original put back in.

 

Rochester: I look forward to you observations on the stiffer tranny mount.
My previous car had a super smooth inline 6, so the 3.7 V6 feels and sounds very rough. I would not want any more noise/vibration.

As for a 5-6 grind in our cars, I can't see how a stiffer mount would make any difference. The actual issue is the cone of the synchro is not getting the gear up to speed before it is engaged. Assuming the car is being shifted properly and the clutch is fully disengaging, grinding is only caused by two things: (1) worn synchro (cone) and (2) wrong/old transmission oil (too slippery).

 

My last Nissan really liked Redline MT-85, so based on that I put that in my G at the 20K mile mark. Didn't notice a single bit of difference.

I don't have this 5-6 grind issues. The only gear that ever catches for me on the G37 is 3rd, and even then, it's a rarity. And it's not a grind, per se, more of a little snag.

 

^^How long have you had the mt85 in your G? How did it perform after a while in the winter when temps < 32F?

My experience was poor in the cold after about 18 months/8K miles. Shifts from 1-2 were near impossible until the fluid warmed up.

 

It's been in the car for about 10k miles, and two Northeast winters. Haven't noticed anything unusual in the cold.

In so far as I can generalize over 4 years, the last 2 with MT-85... 1-2 shifts are always difficult in sub-freezing temps when the car is bone cold. But that changes almost instantly.

 

Right, until the fluid warms up, then it's ok. Last winter (14-15) I swapped out to stock fluid in january. Big difference in the cold. Not 100%, but probably 85-90% better. It's worth noting, when the fluid (mt85) was new(er), that first winter with it in was not bad at all. It seems after it broke down and cold temp shifting when to cr@p.

Not sure which is the lessor of the two evils. For now i'm sticking with stock fluid

 

I've had an issue with 3rd catching as well. After a lot of research on this forum, I saw that many who were under warranty had the transmission replaced due to this issue. I'm still barely under warranty and have plans to take it to the dealer and see if they will do the same. But I'll also have to put in some new MT fluid. It's about time. Not sure if it's ever been changed - bought the car with 51,000 miles on it.

 

Please describe what "3rd gear catching" feels/sounds like.