Hello,

Issue:
I am having issues shifting into first or any gear from a stop, but once the Z is moving (when I get it into gear) it shifts with no problem.

Observation:
The shifter will wiggle left and right as normal, but it feels like something is blocking it from going into gear. I can get it into gear if I roughly shake the shifter from 1st to 2nd, or sometimes force it into 1st. Once the Z is going it shifts just fine, mostly. I think my transmission is going bad.

I have a 2003 Nissan 350z base with a 6-MT. The car has about 79k miles. I had a shop install an ACT clutch and flywheel, and a Kaaz metal 1.5way LSD a while back. Admittedly, I stopped going to that shop due to them constantly making errors that I ended up fixing(that's another story). I never did check their work on the ACT clutch, flywheel, and Kaaz diff in depth.

What do you think? Syncros going bad?

Thank you ahead of time!

 

You left out something very important. Mileage?

 

probably need to adjust clutch pedal throw to make sure that the pressure plate is getting fully engaged

 

79k miles on the car.

Thanks! Going to update the previous post.

 

That is a possibility. It does go into gear at times with no problem from a stop though. It seems like it works when it feels like it, haha. I'll look into this. I need to bleed/change out the clutch fluid anyways.

 

I agree with str8dum1. Obviously you can have transmission problems at 79k but its not the norm.

 

davidv, I will definitely look deeper into it. On the other hand, this car is my track car so she has been beaten pretty hard in the last year, since I got her.

One more observation: When the car does go into gear and driving normally, the clutch disengages the gear around 40-50% of the way down.

Just a clarification, when I say it won't go into gear, I mean the shifter will not physically move into the first gear position. Once I physically am able to get the shifter into the first gear position, the gears engage and work fine.

 

That is how my Z felt when my clutch was going bad. I had a Z1 package put in and all better. I bet your clutch needs adjusting. Make sure you do that before you start thinking transmission. I bet your problem is easier than that.

 

I've been worried about that. The clutch and flywheel, ACT, are less than a year old, but the shop that did it sucked so bad that every time they did work on my car. I had to end up fixing something they missed. Learned a lot in the process though. I wouldn't be surprised... I will check that out as well.

Aarrrggg, they installed my LSD as well. I already fixed a dump error by them with the side flange. I will need to look at that as well.

This is the reason I don't take my car to shops anymore. It takes me 4 times as long to do the work myself, but it has always been good and clean.

 

Update:
Ok, I did some testing yesterday, trying to repeat the issue. Came up with a couple of theories and ruled out some of the issues. I think I've ruled out the transmission being the issue.

Important Notes:
A few things to understand before hand. I have a Kaaz LSD 1.5way, a clutch-based diff set to 100% lock. At low speeds, with minimal torque going to the LSD, it will cause the rear wheels, rear end and diff housing to pop and viberate quite a bit. This jousels the drive shaft then transmission, then clutch, and then motor thus the transmission and motor mounts.

Observations:
When I left work yesterday, I had absolutely no problems shifting into first. When I started having to do slow moving turns (5-15mph) then stopping with the wheels and diff popping and making it's normal noises. I started to have problems shifting into first.

While at a stop on a small uphill, the gears locked up again. The shifter would not go into gear as usual. I was curious, so I let the car roll backwards lightly, felt the LSD shift, locking or unlocking the clutch-based LSD. I could then easily and smoothly shift into first and all other gears.

Possible Issues:
That leaves either the clutch, motor or/and transmission mounts, and LSD causing the gears to lock, preventing me from shifting from a stop. It could also be a combination of these issues as well. The diff mounts could be blown as well.

I think the LSD is upsetting the transmission and possibly the clutch, misaligning something to cause the gears to lock. Going to review the service manual to more ideas and insight. Any other thoughts?

Pretty much, I will need to check diff, trans and motor mounts. Then bleed my clutch lines and adjust clutch pedal throw, do more testing, if that doesn't work, I'll check the actual clutch and flywheel, and drive shaft alignment, test some more. If I continue to have issues, I will need to inspect the LSD installation.

 

^ did u get this fixed? I just now had the same problem today

 

No, not yet, but I did bleed my clutch last night. The clutch is a bit smoother, but still not where it should be.


mknZ, What year and how many miles do you have on your Z? Also, when was the last time you changed out your transmission fluids? That usually helps smooth things out for me a bit, but only to a point. I track my car so I am constantly changing fluids.

Observation:
When I first started driving in the morning. It was smooth and had no issues, but it started locking up later during my commute, again only from a stop and maybe some odd shifts to 2nd.

My clutch has always been very stiff, but I didn't realize how bad it was until I drove a few other manual transmission cars this past weekend. That is why I bled it. That didn't help very much. I think I need to replace the master & slave clutch cylinders.

Thoughts:
On the bright side, I did learn something because of this though and I am starting to see a pattern, getting closer. It seems like this does not occur when the car is cold, when I first start it up. I did do some additional testing and can confirm that when the gears lock; I can shut off the car and turn it back on, really quick, and then I can shift the gear into first. This is only temporary and really only works for one stop, but it seems to work everytime. I will do more testing to confirm if it is 100% consistent and report back.

Could it be my master and slave clutch cylinders? I ordered some new ones. I think they are going bad, even if it isn't related to this issues; I am going to replace them anyway.

If that doesn't help, I am going to need to open up the trans/clutch/flywheel and do some poking around. Check the alignment and all that.

Anything I should replace while I am replacing the master and slave cylinders? Any other ideas?

 

I have exactly the same issue, going with your transmission mount theory I figure if the mount is going bad the whole thing would drop, as in the tranny would sag towards the ground. Funny thing gravity always pulling everything down
So today when the problem shifting into first happened today I pulled the shift **** up toward the roof of car with as much force as I have at 6'4 250lb and it worked, reasoning if its sagging its a 1/4 inch or so and about 100lb of force pulling it up should do something. Don't get me wrong it was not smooth or easy but it DID WORK, without rolling the car or shutting it of.
Needles to say going to take a look at the mount tomorrow...
Thanks for eliminating all the other possibilities....as a result I learned how to adjust the clutch and its in such a sweet spot now I'm living it.....When it does go int gear that is

 

Update:
turns out the transmission mounts don't go bad, precizionz at least have never seen a bad one, and these guys know their s#*&.... They believe its the clutch disc itself.....
To elaborate after checking everything my guy belives that the ACT clutch is worn down past the slots (like on brake discs). When the disc is flat, no slots, it sometimes sticks to the flywheel...it creates a vacum and it doesn't separate air cant get in, it seals it self specially when its hot....... Thats why it works fine when its cold....
Thats the theory he seemed positive that is the issue...
Also he showed me that as soon as you put opposite momentum on the drivetrain ie reverse it unlocks and works fine, which backs up his theory....
The other thing I also noticed is that when the problem occurs my clutch does not rattle as it should... the z specially with aftermarket clutch rattles in neutral...
Makes sense if the clutch doesn't separate it wouldn't be free to rattle
I'll just drive it until it becomes really bad, right now I just shift down as I come to a stop and its smooth as butter, only happens when car is hot stopped and then taken out of gear....
When I do replace the clutch will still do urethane tranny mount for a different feel just for a change.....

 

Hi gorilko,

I got my car into the shop this week. I will report back with what they find out. I am going to have them replace the master and slave cylinders just for kicks (it's not going to fix the main problem, but they master and slave cylinders are having issues of their own). One of the guys mentioned it could be a bad pilot bearing; he was just theorizing. I am going to get my trans mounts changed too. It wouldn't hurt, plus it might improve stability a bit.

Yep, we are having the exact same issue. My clutch doesn't rattle anymore as well.

 

I got my car back from the shop last week. The issue seems to be gone. I took the car to the track for a PDX event this weekend. She handled like a champ, holy crap! I have never felt more confident in her.

This is what the shop did:
Replaced the stock pilot bearing with a Nismo pilot bearing.
Installed a Sikky Trans Mount.
Put in Motul trans oil.
Bleed the clutch.
Clutch and flywheel were fine.
Master and slave cylinder were fine.

The Sikky Trans Mount add more vibration, but wow the car feels tighter and sounds like I have an after market exhaust on the car, crazy. I'll upload the video of my track day.


Analysis
A note from the shop: They could not repeat my issue.

In retro spec: I believe the issue I was experiencing in part due to the way and when I was shifting while slowing down.

Before I put my car into the shop. I didn't have a lot of confidence in my transmission. The clutch was spongy and very heavy. I babied it, sticking in the lower revs (probably too low) and going to neutral while slowing down to a stop.

Now, I am a lot more confident in her. The clutch is extremely smooth and anything but spongy. I now down shift as I am slowing down, rather than putting her into neutral, and keep the revs higher.

If anyone else has this problem. It may be related to the pilot bearing, trans oil, or your driving/shifting style.

Got any questions?

Cheers,

Hyde

 

Thanks man will try...

 

How much did they charge you for parts and service? I'm wondering if it's something I can do myself or have a shop to do it for me.

 

What exact Motul trans oil did you have put in?

 

Honestly I don't think you had a problem to begin with. The Z's tranny does that. I literally just dropped in a brand new CD009 w/Z1's mild clutch/flywheel kit due to grinding 3rd and 5th gear, but it will still sometimes not go into the 1st or 2nd gear gate when I'm at a light. What do I do? Hunt for a gear I can get into then it goes right into 1st no problem.