shift problem - crunch into 5th gear
 

need some friendly advice, after the recent night of tracking and using 5th gear. (Road Atlanta makes use of 5th gear. )
I now have grind/crunch/noise going from 4th to 5th, or 6th to 5th.

recently had the transmission fluid changed to Redline MT-85.
Also looking for a new short throw shifter, the Stillen, gets loose, (its not a solid piece of metal, uses a bushing)

So options Transmission
-- Take to dealership and see what they say
-- any others..

Options for short throw shifter for now
- Torque Solution Short Throe Shifter
- B&M Presision Manual Sportshifter
- Coolerworx Short shifter - looks good, not sure if it can be found in USA
- TWM Performance shifter - no longer made..
- still looking

Thanks for the help

The synchros in the OEM manual trans are crap. They are known for grinding in to gear when power shifting. Only 6th gear grinds on my Z (for now). I can power through 1st through 5th with no issues, but if I want to avoid grinding in to 6th, I need to push the clutch all the way down, wait a second and then shift in to 6th. I took it to a reputable place in Maryland a few years ago and they recommended replacing the trans with a new one. That seems to be the general consensus with this issue. Or at least it was back then.

As far as shifters go, I installed a B&M short throw about 10 years ago and haven't looked back. It works well, was easy to install and I've never had any issues with it.

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Change the fluid to GL-4 75w90 and see how it does. Nissan trans do not like a straight 80w or 85wt transmission oil.

Mine has always ground going from 6th to 5th if I rush it. Different gear lubes haven't help. Plus I have the TWM shifter.

Have you tried Amsoil MT transmission fluid? That is what I use and it works like a champ.

I always get crunch from 4-5 when the trans is cold if I shift too quickly. Crunch is mostly gone when the trans is warmed up. A granny shift into 5th for the first few minutes of driving is all I need to do to avoid the crunch.

Using MT-85

Yeap, that would be due to the 85 weight. A 75w90 won't do that. It is even worse in cold weather.

Here is what I use.

https://www.amsoil.com/p/manual-tran...be-75w-90-mtg/

Redline MT85 is actually 75W85 oil. The naming convention is a bit misleading


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Ah, makes sense.

Thanks all, very interesting stuff...
Not sure what to do, might try the AMSOIL Manual Transmission & Transaxle Gear Lube 75W-90

But it appears it might not need a new transmission, hmmm...

On the list is to check the fluid level and see.....

I guess the other question is how much does this affect Track Days, now I do Atlanta Motorsport Park (AMP) and Road Atlanta (RA).
AMP - never get into 5ht.
RA -- all the time

do you buy it direct from Amsoil or do you know any major chains carry it.

Didn't help.

Yeah the 5th gear synchros are the worst/weakest. Try changing the fluid but budget for a replacement sooner rather then later. After a track lap where I was pushing pretty hard for a good lap time and didn't wait for the synchro and forced it, the whole 5th synchro was destroyed and I had to limp home with it jammed in 5th. Ended up just replacing the whole transmission rather then figuring what was damaged and what wasn't and rebuilding and just being more mindful of the gearbox limitations.

OK, understand all of that... Or the other solution don't do tracks that require a 5th gear, which would eliminate Road Atlanta and Mid-Ohio. Barber Motor Sport not sure of there, but will be there for the Zcon

Funny thing I do not remember anything that felt odd, no indication that it happened. Like I said, went to come back to TN and bam, what is going on... Still when I take it out, I wish some overnight would fix it...

Thanks for the help :tiphat: