370Z clutch line restriction
 

I've been working with a vendor on the 350Z forum to provide a solution for the Secondary Clutch Slave (CSC) fitting problems with the pressure plates the vendors are providing for our 370Z's. If you have a close look at the CSC's and how it fits and works on some aftermarket pressure plates, you can see the stock fitment is less than ideal. It has been my experience that the CSC's will eventually fail and cause all sorts of problems. I had my fair share of grieve with my 07 HR and CSC failures.

As part of my research I've taken some pictures of my 370Z clutch line layout and disassembled the clutch line block to discover there is a restriction orifice in the block that may cause hydraulic failure with enough heat and cycles. The clutch line is roughly 7 mm ID and the RO is roughly 3 mm ID.

The other difference between a HR and VHR is that the Master Clutch Cylinder is shorter in the 2009, compared to the 07/08 HR's. Other than that the clutch line layout is identical and so is the CSC.

More info and pictures to follow once I get the new CSC kit and clutch line delivered. I will also be installing a new flywheel and clutch from this vendor as well. If all goes well, I hope that they will become a vendor and offer this package to our members here.

so drill out the restriction or stop by the auto parts store and ask for a 10mm brake line union. If you have to have a piece with the mounting tab i can find you a Toyota part number for one. Nissan probably uses one as well but i don't know the Nissan platforms as well as the Toyotas.

Not as easy to drill out the restriction. Not enough material to ensure a proper seal with the flare connections on the clutch line.

Haven't measured the connectors yet to know what size or thread they are yet and yes, it would have to be a brake line type union with the proper flare connection fittings to prevent leakage.

They will either be 10mm or 12mm they are "measured" by the wrench size used on them. I'm guessing 10mm by the rest of the clutch system. and like i said hit up and auto parts store and ask for a brake union fitting.

BRAKELINEUNION - Dune Buggy Parts, Sandrail Parts, VW Parts - MooreParts.com something like that.



90412-10144 Toyota part number if you must have the 6mm hole for the mounting tab.

I believe the Z1 and GTM clutch lines eliminate this section of tubing completely so shouldn't that restriction be gone if you upgrade the clutch line?

I don't think either of those lines eliminate that potion. That is actually located inside the wheel well behind the rear fender liner.

I guess I should update this post.

I found that the orifice block available @ Courtesy Nissan is the larger orifice block and is now installed on my car. It is the one that the 2006 350Z uses. Part # 30859-Z33002. I also drilled out the one on the 370Z to 1/8" and it looks like it should work just fine, as well.

The clutch line from the frame to the transmission is one I had made locally. The flare fittings are 10 mm in size. I had it made with stainless line at a length of 15" (stock is 13") The extra length gives a bit more clearance from the header and should provide less heat soak. Plus I also triple wrapped the line with insulation.

So far, no problems.

I replaced the clutch restrictor (dampener) with a Dorman 3/16" brake line female to female union, part number 785-438. The union has ~3mm ID and the Nissan restrictor is ~2mm ID. Nissan's specially machined clutch restrictor, called a "connector", is part number 46364-4P000.

So what difference has it made in the clutch feel?

Wow. Amazing find pal +1

No more delays in clutch release as it's instantaneous. Clutch pedal feel is solid and firm throughout the pedal stroke.

I've also upgraded the clutch and pressure plate to a Southbend brand compliments of Joe @ Z Speed Performance

Do you have a link to the parts you used?

Also this is located inside the drivers side wheel well?

is this 'restrictor' only on the 2009-2010 models?
I have a 2011..

:icon18:
No, this restrictor is on every model year, '09-'14. Its even on GT-Rs.
Its only a $4 part. Install it when you do your next clutch fluid, plastic POS CSC and/or clutch change. :tup:

but... the R35 GT-R has no foot operated clutch?

The same part is also used on various auto trans Nissan models.
I'm guessing it could also double as a brake line coupler and that's where it might be used on the other cars.

If i'm cracking the lines open i'll be replacing it with a braided stainless one for the consistent pedal feel. But i don't enjoy the idea of cramped work space (no hoist) and brake fluid spewing. Maybe i'll just drain all the fluid first hmmm

That's correct. On other Nissan models such as the GT-R (R35), Q45 (F50), Pathfinder (R50), QX4 (JR50), M45 (Y34)...its used as a front brake fluid restrictor, I mean "connector".

this might be a dumb question, but why would a restrictor be necessary?

In a brake application, it would impede the function of ABS pulsating the brake.

In a clutch application it would as people have noticed, make the pedal feel inconsistent and delay clutch action.

Is it to reduce frothing from fluid rushing back too fast?

Most folks who have upgrade to a braided stainless line report smoother and more consistent clutch pedal feel. As expected, a lot of the consistency is due to the stiffer walls of a stainless braided hose but these replacement lines also eliminate the hard line that goes between the stock flex hose and the slave.
What is the purpose of this short section of hard line? (i guess the same question should be asked about the way the brakes lines are connected to our calipers - why is there a need for a short hard line between the rubber hose and the caliper?

it is made to smooth the clutch engagement so the clutch doesn't snap closed when you release the pedal. It makes the car appear smoother(which doesn't really work) and keeps you from shocking the drivetrain as much. On all firebirds and corvettes this little bass terd is in the middle of the frikin line and you need an 8" long 1/8 drill bit to drill it out as it has been known to plug when the fluid gets hot and old and totally F you in A after some hard driving. in brakes i would say it may play a role in residual pressure.

that's a very good explanation - thanks!

why would the fluid 'plug' the orifice when hot though? unless you mean debris in old fluid accumulating? i cleaned out a layer of gunk at the bottom of the clutch fluid reservoir so i can imagine there's more crap further downstream :|

thanks again mate :)

yup it's gunk for w/e reason it happened the most on old fluid while it was hotmaybe the heat made the csc stikier so it took less blockage to actual freeze it up? maybe the crap clumps together easier in hot fluid? i don't know on that one.

Nice work. Subbed to replace and rep given

those who have stainless clutch lines, do you remember how big the hole in the banjo is? Not the one where the bolt goes thru but the one from the hose side.
I have a HEL line but the hole in the banjo looks smaller than the hole in the orifice i removed. Speaking of the orifice, wouldnt it be better to not use a joiner and just get a longer flexible line made up which connects straight to union before the orifice, direct to the slave bleeder block via banjo or union connection?