clutch sticking?
 

if i accelerate to redline in 1st gear under hard throttle and very quickly shift into 2nd and very quickly lift my foot off the clutch, i noticed that the clutch pedal sticks at the bottom position for a split second before bouncing back up. In other words, the clutch pedal doesn't bounce up the same moment I lift my foot off, but stays pressed down for about half a second or so before bouncing up. This doesn't happen at lower rpm, only at very high rpm near redline. It also doesn't happen if I shift slower and lift off the clutch more slowly. I haven't had a chance to redline in any other gear so i don't know if the same would happen.

That never happens with my Mustang.

Interesting.....I say try the same theory with the gas pedal....however this time....don't let off of it....even if you see a traffic jam forming in front of you. Report back....I'm in for pictures and details. :tup:

Omg... I have a lot of rep to disburse when I get home tonight!

I swear I read about this a few months ago, though. Someone here was experiencing the same thing.

Was it after a hard launch?

and your point?

yeah, it only happens during a hard launch. i tried searching the forum but nothing came out, so i started this thread.

Yeah, you probably overheated the clutch. I think this guy was at the drag strip and after a few launches his pedal would go to the floor and stay there.

:wtf: huh? u retarded or something? :gtfo2: and don't come back

I don't think a split second under a hard load should be anything to be concern about.

That would happen.

no i dont think that's it. it happens during normal driving. i'd be driving normally and if the streets were empty like late at night for e.g. i may try a hard launch from a traffic light and it happens right there. i don't see a reason why the clutch would be overheated since i'm driving normally. also the pedal doesnt stick, it comes up. it's just that there seems to be a lag of a fraction of a second between me lifting off and the pedal coming up

is it normal? but why would it happen though? the clutch is spring loaded, so as soon as the force stretching the springs (i.e. my left foot) is removed, the springs should recoil and push the pedal back up immediately. in this split second, what is the force resisting the springs? is it possible that the large torque causes some minor twisting perhaps of the input shaft of the gearbox relative to the crankshaft or whatever that causes some friction and holds the clutch momentarily? at least that's my theory.

i don't think it's anything to worry about either. more than that, i'm amazed you can actually tell a 'fraction of a second'.

i doubt the torque would twist the input shaft of the gearbox enough to choke a clutch either, or we have a real bad design problem on our hands when people go FI and try to launch those suckers. if anything, maybe it's just a little blip while the clutch tries to settle in to the really fast spinning flywheel.

note: i'm obviously not a mechanic, so someone with more experience speak up.

You do know your clutch is hydraulic right? :)

Ok, but what does that have to do with the 370z's clutch?!

^ He was being sarcastic..

This happened to me as well during a trackday. I purged my DOT3 clutch fluid and switched to DOT5.1 (take note of the .1 since DOT5 will destroy normal clutches) which essentially gives a higher boiling point threshold.

Pharmacist, I seriously doubt you have an overheating clutch issue. However, you might want to inspect if you have the proper clutch fluid level on your reservoir. If you have the correct level, then you might want to try a clutch fluid change first since that would seem to be the cheapest thing to do for now. If the problem still persists after the fluid change, then I suppose there is no other alternative but to open up your clutch and check for wear.

The clutch pedal is a master / slave hydraulic cylinder configuration so I doubt its a faulty spring issue. Also, you might have air bubbles in the hydraulic system.

By the way, were you able to fix your gear buzz / rattle above 5k rpms issue? I moved my shifter boot up and down countless times and I still suffer from the buzzing issue at high rpms. Don't really know what else to do.

Thanks!

at least it wasn't the other gas pedal sticking to the floor like a toyota... :D

are there any drivetrain breakage prevention safety device on this machine?

This is inherent to Nissan slave cylinders; my G does the same thing. Look at it as an additional safety measure.

This happens to Corvette guys all the time. It's a Heat issue for them.

This happened to me one night one the way back from the mall.
Maybe 2 months ago?
It would get stuck and pop back up.
After I turned the car off and on it never happened again.

Never really had this problem before. Could it be due to the weather? I've never had a clutch stick the floor. I do drive my Z hard occasionally, but usually just spirited and normal driving. Could it be also that the way you drive? Maybe he drives it hard often? Either way I think thats something that should be taken to the dealer to be looked at if your not so mechanically inclined like me. Just a thought.

Slave cylinder Issues
 

Nissan salve cylinders are the issue. I had the same problem swith my previousl 350Z. I swapped out the stock slave cylinder line with a SS one. In have not had this issue with my 370Z yet. I am not sure the 370Z is internal or external. Others can chime in if they know.

Firing this thread up again.. I get weird clutch action when I modulate clutch and gas e.g. merging into another lane/ getting around a stopped vehicle etc. with lots of gas, the clutch doesn't want to engage so it sits at the bottom of the throw range and sort of comes up a little if I reduce throttle- and I have to completely let off the gas (with traffic approaching from behind- fun) in order to get the clutch engaged. It's happened since I bought the car new, again today getting around a Mustang crawling over a minor RR crossing, with lots of clutch smell from the slippage. Is this just the traction control ( usually off if I remember to ) or an issue with the slave/fluid?

It's the master and/or slave cylinder. The slave is a CSC that is inside the transmission, so it needs to be dropped to replace. You can visually inspect it by prying the rubber dust cover were the clutch line meets the slave. Watch for fluid leaks.

Same here, I remember when I was driving the 350z, they had a recall on the vehicle about changing a part that is related to the slave cylinder, I have the job done at the dealership at no cost.

However, at about the 3rd year driving the 350z, I notice the 'pop' action from the clutch pedal, especially in cold weather.

Pharmacist, is your 370z still under warranty? you might want to have the service department take a look at it.

haven't had any problems since i replaced the fluid with motul 5.1 it's probably heat related.

That could be it. I noticed earlier in the thread that you said it happened during normal driving....

Once you overheat brake or clutch fluid once, it's never the same and you need flush and refill the system. So you could have overheated the clutch a month before you even started noticing the issue. We stock Motul fluid, and I strongly recommend it to anyone that's going to be driving their car hard.

I would also recommend exploring the idea of upgrading the clutch line and clutch fluid before considering changing out the slave cylinder.

I'm also wondering if changing out the OEM cats could contribute to the deterioration of the stock fluid- does anyone think that test pipes would give off enough heat during hard driving to possibly boil the fluid?

I boiled mine a few weeks ago and it was pretty cool out. Pedal has been soft ever since. I have the hardware and fluid in the garage waiting for the upgrade this weekend.

(also this thread should really be in the tech section)

i still get an occasional gear grinding/missed shift while downshifting from 3rd to 2nd on the track but it only happens after 15-25 minutes of lapping, and not at the beginning of the session. I also feel the clutch pedal getting a bit softer (not sure if true or just a false perception). The Motul fluid is about 6 months old now with 7 track days on it. I still believe there is a lot of heat going into the clutch lines causing boiling over of the fluid and sticking pedals and gear grinding. Next summer I might consider upgrading the clutch lines or maybe wrapping up more heat insulation around it.

thanks for your help.i too was having similar problem.

I have had my clutch stick to the floor after 3 hours of really intense traffic but that is due to over heating. I too have had the same problem you are describing. When i do hard shifts starting from a stop position and i shift quickly i have had the clutch pedal stick to the floor for a quick second. I wouldn't worry about it though.