JWT clutch is just too damn good... unfortunately...
 

So I've had the JWT heavy duty clutch installed for about 10,000 miles now and have been loving every minute of it. It has a real solid feel and I have had not one issue with around 10,000 miles and 2 track days under it's belt.

But...

The other day I was driving home and a few blocks from my home I depressed the clutch pedal to shift and it decided to stay on the floor. Well I figured I had lost my clutch fluid one way or another and since I was so close to home, I decided that doing a little "floor shifting" with about 1" of pedal pressure left would do the trick to at least get me home. It did... leaving a little trail of fluid right up to it's final resting place in my driveway. I had just driven about 50 miles round trip that day with normal driving.

It was dark so I had to wait until the next morning to asses any problems. Once the sun did come up the next morning I could see that the last bit of clutch fluid that had gotten me home now lay in my driveway. I called up AAA and had the bee flatbedded to my local Nissan dealership for a looksee.

It went it pretty late in the afternoon so the next morning I get a call from a Nissan service tech who informs me that my master cylinder had blown out and hence was the culprit. Then he informs me that repairs will not be covered under warranty as I have an aftermarket clutch (he also noticed the aftermarket flywheel). I half expected this but it still stung to hear it over the phone because now I know the $$ are going to start adding up.

The tech goes on to tell me that the clutch is very good and the specs are all right on the money however the pressure plate is entirely too stiff and while that may be what JWT was going for here, when it's coupled with a stock master cylinder, problems can (and in my case) will arise.

So the bottom line is that my car is up on a lift with the transmission hanging off and the replacement and repair of the master cylinder is going to run me $1,000.

But...

The tech tells me that I most likely will run the risk of this happening again if I don't either:
A. Put an aftermarket master cylinder in or..
B. Put the stock Nissan clutch back in.

So I make a phone call to my buddy Phil over at Vivid Racing to inquire as to where I can get one. My understanding was that with the 350Z, a beefed up aftermarket master cylinder was available so it only stands to reason that one is available for the 370Z. Not so much...

So rather than run into another $1,000 down the road (not to mention the inconvenience) I decide to have Nissan put the stock clutch back in.

Now I'm up to $1,800. out of pocket. :shakes head:

Well I did get the JWT clutch for free as I was one of the first and they did a write up on the install etc., unfortunately FREE comes at a HELL of a cost.

Oh well.... I guess that's what I get for playing guinea pig with new products (which is exactally why I'm waiting a good long while before going FI) What really blows though is the fact that nobody's looking to develop the aftermarket master cylinder as the economy sucks and there really isn't a demand at this point. :shakes head:

Let this be a warning if you are running the JWT clutch I guess. Unless JWT or somebody else (Stillen?) wants to develop something for us, then I guess you will see my clutch up for sale here soon.... :icon14: Thankfully I didn't find this out at the track :shakes head:

Edit: Update on page 3... the culprit was the CSC

Damn, that sucks... but thanks for the heads up.

I think Zat Zuma mentioned something about an after market master cylinder in development.

Damnit Dreamer! I didn't see this thread. Thanks :tup: Well it's a little different in that RCZ is asking about any potential problems and I want to make sure that we have a dedicated thread WITH the actual problem... lol

TY.. I will look into that. I hope they come out with something so I can go back to this clutch as I do like it... but not until then.

Yeah, good to know it will be a problem, sucks it happened to you though. :(
Glad I did not get a clutch/flywheel right now then, will keep an eye on this development.

Sorry to hear that Killer.

Try this Bee. I think this will help you

370Z Report Clutch CSC failures – Must read before clutch upgrade! (Solution)

Nice! :tiphat:

sorry to hear that, +Rep for the heads up.

Try offering 1800 mexican pesos.... they'll never know the difference.

The OS Giken in our 350Z HR comes with a similar TO bearing sleeve as the one mentioned in LateralG'z link, and the CSC still went out after a few thousand miles. Unfortunately, the stock CSC just cannot handle the added clamping pressure of most aftermarket clutches.

Someone needs to make and race CSC for the 370Z! hmm wonder how are hard it would be to make one?

I don't know but it sounds like a reasonable idea given the amount of track driving that a lot of 370 owners do.

Sorry to hear.

Genaro told me at the meet and I was bummed for you.

damn dude, that sux. i hope this problem gets sorted for you.

maybe you should buy a 300zx to tinker with and leave the 370z alone.

I'm confused

Did the clutch master cylinder blow out or did the Concentric Secondary Cylinder (CSC) go?

For clarification the CSC is located on the transmission shaft and releases the clutch from the pressure plate. The clutch master cylinder supplies hydraulic pressure to move the CSC.

I won't comment until I figure out which part failed.

I do have some updates from Southbend on their product development.

That is a good question. I will find out today from the tech exactaly what happened and update the post.

This is Phil @ Vivid Racing!
 

I am sorry that the cylinder failed. I called you maybe last week. Unfortunately I have found out that as of the moment there is no aftermarket available (according to Stillen and JWT). BUT after I have informed Stillen and JWT they are doing some research into this. Both companies really can't believe that this has happened to a 370z. I will keep trying to look for a solution for you hopefully something will pop up. I have a lead from the great guys at Stillen telling me that the "jdm" cylinder they have heard might be better. I am trying to locate and get one for you. I hope everything works out and I will keep you updated to my findings.


Thanks,
Phil

IIRC a member from Australia had his master cylinder fail with the stock clutch... wonder if the clutch is really the culprit of the failure or if it was just a defective unit in your car, KB?

I don't think it's the clutch, but I've heard the slave cylinder is the weakest link. Nissan issued a recall with the '07 Z with some users reporting sudden loss of clutch pedal pressure causing it to sink to the floor. At least one owner got in a bad accident because of the pedal sinking to the floor.

Recall on slave cylinder - MY350Z.COM Forums

I'm surprised this issue exists with the 370Z. :shakes head:

I'm not surprised the stock CSC is a piece of junk and will not handle the pressures of a heavier pressure plate.

Read this: CuztomPartZ HR CSC Concentric Slave Cylinder Upgrade and INFO - MY350Z.COM Forums

I was warned about this a few weeks after I installed my new clutch. I've been talking to ZSP because they are engineering a full metal CSC replacement, not sure what the status on that is. Unfortunately, my clutch is a ticking time bomb right now. Fortunately, my Southbend clutch is a lot less stiff than the JWT so it should help lengthen the life of my CSC. Hopefully I get lucky and it doesnt happen for a good while, but I'm going to get AAA in the meantime.

The technitian that is responsible for my car is out today so I couldn't get an answer as to weather it was definitively the Clutch Master Cylinder or the Concentric Secondary Cylinder. I too would like to clear this up.

I will try to get my hands on the failed part/s in question so that I can take some pics and possibly get these item/s into the hands of JWT and or Stillen etc. so that some R&D can happen.

Anything is possible. I suppose it could be a faulty unit but my suspicion would be that the pressure plate is just to much for the stock cylinder and or the consentric unit.

To be clear, I never experienced any loss of pressure prior to the fluid dumping and my clutch pedal heading south never to return. Everything was in fine operating order until this happened.

I had the same problem 2 weeks back while driving the Alpenstrasse in Germany, driving along, go to change down and clutch pedal goes straight to the floor no pressure what so ever, the following morning clutch pressure was back checked fluid level all was ok.
Got the Z to the dealership after convincing them there was a problem it took them 3 days to get approval and parts from Nissan. They replaced the slave cylinder, CSC (in the old days would be the release bearing) and the steel hydraulic pipe to the CSC.
Had a look at the parts when collecting the Z and it was the CSC that had gone and this was with only 4550 miles on the clock

forgot to say stock clutch assy

Damn I want a clutch upgrade but this is making me a little hesitant.

Likewise. I will have to wait it out until there is a resolution.

CONCENTRIC SLAVE CYLINDER master-slave i know i'm a finicky a$$ about this stuff

Also lots of cars now a days use the concentric slave cylinder/combined throwout bearing setup, it isn't new it's just failed engineering thank the french they designed and made this part and the tranny. frickin resource sharing with renault.

--------------------------------------------------------------------------------

does anyone know if they have changed over the slave cylinder part numbers over the years? is the nismo slave stronger.

Just found this with a 30sec search on yahoo.

NISMO Slave Cylinder - Nissan SR/KA [ NIS-SLV ] - Enjuku Racing - Performance Parts and High Quality Fabrication

its for a 240 but maybe there the same

Good find. Diving deeper into this today when I get back from class...

Sorry to hear what happen to you KillerBee. I feel like I'm on a ticking boom. lol

Hope some company will get this issue sorted soon. coz I can't imagine my self going back driving with the stock flywheel.

Thanks for taking one on the chin for the aftermarket community, I hope the car gods find a way to repay you. I had a feeling the clutch master cylinder would have to be changed out, in all aftermarket clutch/flywheel applications I've researched it seems that the cylinder is the weak point. Guess I'll have to wait along with many of you until a quality aftermarket one comes out before upgrading my clutch.

This should be a high priority for atleast a few developers out there. Many people are clearly going to go F.I. within the next year and the clutch will need to be upgraded. Rather than constantly cycling through OEM clutches, we need a master cylinder so we can get a lightweight one in there and watch the rpms climb and drop 10x faster!

I don't think flywheel's got anything to do with it. I'm leaving my JWT flywheel in. At half the weight of the OEM AND picking up 5 whp on the dyno... THAT was a good investement! (Even though I got gratis as well)

Hopefully picking car up today. I will put a call in here now and report back with a more solid answer as to what the tech found out as far as whether it was CMC or CSC.

Hang tight...

We'll be coming out with an upgrade to the OE Slave and addressing the bearing diameter problem for aftermarket clutches. Stay tuned!

:tup:

:tup::tup:

You make we buy :tup:

Good to hear

I did a quick search of the thread, but I'm wondering if the stock master cylinder is made out of plastic or some plastic composite material. This is the case on the Evo X, and people seem to blow them out as soon as a stiffer clutch goes in.

If so, this must be a common cost saving item with manufacturers. Metal is clearly better for something like a master cylinder... kind of disappointing for supposedly race-capable sports cars to have weak points like that.