Clutch help please!
 

Hey guys, I made a post a few weeks ago thinking my issue was resolved but it isn't. I'm pretty new to forums so please bare with me.

I have a 2004 (2004.5) Nissan 350z 6MT. I have 156k miles and purchased the vehicle (from a friend) at 149k miles. He has owned the car since 30k miles.

If I understand correctly, 2004.5 350z's have the 2005 transmission.

When I start the vehicle in neutral, it starts up great. However, while stepping on the clutch and attempting to enter 1st gear, it will not enter. In fact, it won't enter any gear while holding down the clutch. There is no grinding, no noises, nothing. I do notice that when attempting to budge into first gear the car does push forward a little bit but goes back because the gear will not enter.

After giving it some gas and messing with it, it'll enter 1st gear (or any gear) extremely smooth with no issues at all. IF I keep the clutch held, I can enter any gear and the car acts perfectly fine. HOWEVER, if I release the clutch in neutral and try to step on the clutch again to enter gear, the problem persists and it won't enter until I mess with it for awhile. Again, there is no grinding, no sounds, nothing.

When I am in motion and driving, all the gears have little to no resistance. Only 1st and 2nd gear are a little hard to enter while moving, but there is no grinding or any sounds while attempting to do so. The clutch feels nice and sturdy and comes back up all the way by itself.

I tried testing for clutch drag by putting the car into 1st gear and holding the clutch down and revving the engine to 8k RPM and the car didn't budge forward at all. I was told that if the car were to budge forward while the clutch is down in 1st then that would mean there is clutch drag.

Any advice or help will be GREATLY appreciated, I have been trying everything I can think of the past few weeks. I know my way around a car, however, I am no master mechanic. I hope I explained the issue the best I can. I'll attempt to answer any questions to the best of my knowledge.

I just changed the manual transmission fluid, I bled the slave cylinder and replaced the master clutch cylinder. None of these fixed the issue.

The clutch was replaced last year (around 12k miles ago) with a southbend stage 2 "endurance" disc as well as the slave cylinder. While driving, the clutch grips onto every gear perfectly and while driving the car has little to no resistance so I don't think it is the transmission or clutch.

My friend (the previous owner) believes the issue is in the master clutch cylinder and that it requires an adjustment.

Thank you in advance!

Based on the year of the vehicle, it sounds like the typical Synchro issue with the pre-2006 350Z 6MT transmission.

It's also quite normal for 350Z 6MTs to throw a little resistance when shifting into 1st and 2nd gear while in motion. More so first gear, even at low speeds. Second gear should be much smoother when in motion, but can still be a little notchy at times.

I find with my 06 350Z with the CD009 transmission that the car won't shift very smoothly into second gear until after the transmission gear oil has a chance to get into the operating temperature range.

What you're describing though, sounds like internal damage to the transmission. Synchros are most likely worn out. I would recommend purchasing a used CD009 trans and swapping it in. I think there's one for sale on the forums right now.
-Icer

This indicates only one thing - the clutch is not fully disengaging. Start by checking your hydraulics. This isi not a worn synchro issue, although your car may also have that, but this is not how that issue manifests itself.

2004.5 and newer actually have the CD009. And while in motion it enters every gear normally, also, there is no grinding. If there was constantly I would assume it was a synchro issue.

I bled the slave cylinder and replaced the clutch master cylinder. Those both are working without an issue now. What else should I check in reference to the hydraulics? Maybe the hoses? I know for a fact there are no leaks, I checked when I replaced the clutch master cylinder last night.

You need to look at the slave cylinder pushrod and see if the movement is to spec. I have an HR, so I can't tell you what that spec is, but the FSM is online. If that's OK, there may be a problem with the clutch fork pivot, or the fork itself, and finally, the issue could be a damaged clutch disk or pressure plate. Any of those things can cause the clutch to not fully disengaging.

Based on what dcains mentioned and the information you provided about already replacing the clutch, master cylinder, and bleeding. There's a very good chance this is a clutch hydraulic issue. Sorry I jumped to conclusions before I read the remainder of your post. The synchros are a very common problem with these transmissions and with the mileage you have it seemed more likely to me.

1st, I highly recommend checking the slave cylinder for any signs of leakage.

2nd, while under the car, have a buddy actuate the clutch pedal and watch the slave cylinder. If the fork is getting a full range of movement on the slave's pivot ball/rod, then there's a good chance everything is normal. If not, then you may need to re-bleed or replace the slave cylinder and bleed again.

3rd, if the slave cylinder looks good (no leakage) and you do see solid movement, it's possible you need to adjust the master clutch rod out a bit to extend the pedal throw.

When you replaced the master clutch cylinder, did you match up the pedal rod's lock nut with the old one?

-Icer

I have a 2004.5 and can 100% tell you the CD009 is only in 2006 and up.

Agree with dcains. Also recommend icer's suggestion with the MC push rod length.

This is from JWT, but the idea is the same. http://www.jimwolftechnology.com/wol...TSPECSHEET.pdf

I'll give an update this week when I get a chance to try everything out that you guys mentioned. Thank you for all of the replies!

My BMW 635 started with the same symptoms last week - pretty sure its a leaky slave cylinder, but I haven't lifted the car yet to have a look.

Unhelpful....but just wanted to say thanks to all of you for sharing your help...love lurk-learning on this forum, really great thread for clutch help and troubleshooting.

Gratefully,

Saved

I haven't had a chance to check the Z but hopefully your BMW issue goes away. Those are nice cars! And if you happen to figure out what the issue is, please post it on this thread