clutch bites slow?

bleunetizen

Not sure if it is just me or all 370Z users get this issue.

When I shift up, the clutch bite is quite sluggish. It takes good 0.5sec (may be a little exaggerated) after I let go my clutch pedal, especially worse going from 2nd to 3rd (redline) where the rpm drop is larger than going from 4th to 5th etc

It feels like the clutch is almost slipping, although it does not slip once it fully bites.

I am suspecting that this is due to the super heavy flywheel on these cars, but my old 350z did not have this problem even with stock flywheels.

I remember seeing some posts about slave clutch cylinder being pos in the 370z, is this one of the symptoms?

juld0zer

Here's a simple test: press the clutch pedal all the way down then suddenly pull your foot back quickly, as if you were doing a clutch kick. Does the pedal almost chase the sole of your shoe or does it lag behind and slowly reunite with your sole?

The Z has a restriction orifice in the clutch fluid circuit. There is at least one that i know of but there might be a second, in the master cyl but i've never inspected our masters to be sure. google clutch delay valves and you will find heaps of disgruntled owners of other sports or non sports oriented cars. Pretty much the same problem.

Simple braided replacement lines wont fix or eliminate it. To get rid of it you need to remove the restrictor which is in the left fender well and get a custom 4mm braided line made up. Most braided lines for our cars are only -3AN. You'll understand the need for -4 inner diameter hose when you take out the restrictor piece and have a look at the hard line that goes INTO the restrictor. It will make you wonder whyyyyyyyyy Nissan, whyyy? Get the line made long enough to reach the slave cylinder port directly and terminate it with a union fitting rather than a banjo because the inlet to the banjo will probably be 3mm or 2.5mm.

Downside is a slightly heavier feel in the pedal but oh man, it makes a massive difference with quick shifts. Slow shifts will take a tad more concentration

bleunetizen

wow awesome information, that's exactly it.

I did some search and found a few posts regarding this including yours too..

I wonder if drilling out the inside of the 'restrictor' will yield the same result? It looks like a simple brass block from photo.. the lines itself probably are the same diameter as the old 350Z's..?

juld0zer

you can drill it out or replace it with a suitable brass union joiner. i have the thread specs at home. But seriously, replace it with a 4mm ID line all the way to the slave. there's another section of hardline between the flexy hose and the slave cyl so there's more (potential) restriction there.

On a side note, the stock setup isnt as bad as a lot of performancs oriented cars - eg R56 JCW, RS megane, M3... The R56 is the worst of the 4. The shifter begs you to shift fast but the clutch delay valve makes you look/sound like a noob driving it.

DOOMMONKEY777

U need to bleed ur clutch with a new motul brake fluid, i had that be4 and get all the gunk out, also about 2k miles later it will start doing it again, but after the second bleed its good for a long time. Theres a DIY on this site on how to do it, best results when done with a buddy. GL OP.

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juld0zer

yeah - only use Motul RBF 600 or better, for the clutch system. I was already running Motul fluid prior to unchoking the hydraulic lines

bleunetizen

Thanks for the input guys

juld0zer, I think you are right, might as well just replace the whole lot while it is all opened up. was just thinking of drilling it out because I am lazy to measure the hose and have it made up etc.. haha it would be great if you can find the thread specs

DOOMMONKEY777, yeah although it has been flushed a few times, I think it would not hurt to do another flush.. replacing the lines will force me to flush it anyway so I think it is a double whammy haha

bleunetizen

and race fluid always of course

Rusty

Also wrap your clutch line with insulation by the exhaust pipe.

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bleunetizen

http://youtu.be/grZZR4r5Zi4

here is a vid from the track, you can easily hear how slow the bite is at every up shift.

juld0zer

I dont have my Z anymore but what you can do is get a length of whipper snipper line and use that to simulate how you'll route it because a coathanger wont simulate the tendency of braided hose to not like bends.

Mine didnt look neat but i cut a hole in the wheel arch liner to make it neat enough.

Yes, definitely Motul RBF6xx fluid only and definitely get it wrapped in insulation like Earl's firesleeve although any fibreglass lined foil sleeve would be fine.

2010Nismo370z

i have the same problem for my stock clutch im not happy how it doesnt grab right away.....if i get a clutch kit flywheel master cylinder and slave cylinder like SOUTHBEND stage 3 clutch will it grab rite away like no DELAY perfect shifting WITHOUT any custom stuff or what?????

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2010Nismo370z

Bump

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RadioFlyer

Can someone take a picture of where this clutch damper valve is on a Z? Google only pulls up BMW threads.

2010Nismo370z

bump

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