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Talk me into a clutch

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Old 03-09-2018, 03:57 PM
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CK_32
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Default Talk me into a clutch

Alright for our bigger HP boys.

What are we all runnin?

Me and one of our fellow brothers in a supercharged 370 went for a quick "spirited" dash the other day. But sadly my clutch slipped HARD in 5th around 4200 RPM and finally let my throw out bearing go out with it.

It was only a matter of time but I figured I'd let the stock clutch burn out while I daily it. But now it's time for a new clutch and bearing set.

I tried to google but most the info is from 2005 and 2009 etc.

I know there was some talk of 2015+ clutches holding top power with out the massive clutch weight.

I need this clutch to be rated for 600+hp/550+tq ranges.

Hopefully be light enough to daily. Closer to stock weight the better. Will see plenty of track use and regular weekend driving.

Last edited by CK_32; 03-09-2018 at 04:19 PM.
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Old 03-09-2018, 05:54 PM
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Cux350z
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ATS Across twin carbon clutch. So streetable and holds great power.
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Old 03-09-2018, 08:02 PM
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CK_32
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Aren't twin discs chattery, really grabby and stiff for street use?
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Old 03-10-2018, 05:31 AM
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Originally Posted by CK_32 View Post
Aren't twin discs chattery, really grabby and stiff for street use?
you will love an ATS across clutch (carbonetics essentially if you search on here...never heard a complaint). It is unsprung however but it drives like butter. You can do hills no problem. Drives better than heavy pressure plate single.

I had an os giken...it was a piece of crap. horrible to drive on the street and grabby as hell.

Single clutches with that tq rating are gonna be heavy on the pedal.
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Old 03-10-2018, 10:16 AM
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I went with Jim Wolf back in the day and I have no regrets. I replaced both the clutch and 14lb flywheel for around $700.

I think it's a pretty good setup and it does take a little time getting used to (the lighter flywheel and stiffer pedal feel) but I like it and I havent had any slippage issues.
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Old 03-11-2018, 08:16 AM
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I have an OEM clutch. No regerts.
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Old 03-11-2018, 04:26 PM
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CK_32
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So do I... She won't hold. 470ish crank is a bit much for it.
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Old 03-12-2018, 05:47 AM
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Interested in this as well. Over 100k miles still running the original factory clutch. ~450hp @ crank holding for now, but I can't believe replacement isn't far away.

I have nothing but great things to say about Centerforce Dual Friction in my last car (3rd gen F-body), but realize they don't have the same following with import crowd.
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Old 03-12-2018, 06:44 AM
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Yea my throw out bearing has been clacking the last few months.

I've been driving on it for a few months at this HP. And it's been fine with normal daily driving. Hell it was fine the whole time me and this kid were messing around.

Then when we actually went for a full run I went into 5th... Everything was fine. But as soon as it climbed up to 4k rpm it just slipped and I lost all power. Tried to get it to hook up and grab again and it would just slip or not go back into gear.

Then I smelt it. Coasted for a mile or 2 and then it finally cooled enough to grab and then it was fine for the normal driving home. Clutch is a little lighter and the throw out is that much louder now.

So for the fact alone it wasn't during the shift into 5th but well after and when the power fully kicks I know it wasn't driver error and me just riding the clutch.
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Old 03-12-2018, 09:14 AM
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You're really looking at a series of tradeoffs here.

Everyone would love to have a clutch that could handle the rigors of a track oriented clutch but with the drivability of an OE clutch for the street.

Pretty tough to have both cake and eating it too. You need the high clamping force and high friction materials of a comp clutch to withstand what you're throwing at it in anger. Yet, softer materials and lower load to keep your left leg happy. Those characteristics are almost mutually exclusive.

But given the marketplace availability and newer materials used nowadays, I would tend to think (in theory at least) that a good heavy duty PP coupled with either a Kevlar/aramid disc or better, a HD ceramic or fermalloy (or something along those lines) disc is what you're going to need to be able resist the slippage and heat generated with 550lbs of torque while maintaining at least a little civility. People throw around HP and Tq ratings like cred jellybeans but there's some SERIOUS forces at work there.

No matter what you get (with the above Tq holding capabilities), there's NO way you're going to spare yourself the increased pedal pressure required to operate the car. You NEED the higher pressure plate spring rate and with that, a commensurately higher duty friction material, both of which will give you "left athlete's leg".

I DO NOT have any specific recommendations for you, unfortunately, as I take more of a "Lotus approach" to my Zs (of today).... emphasis on handling, weight loss, and relatively "low" power levels. However, when I was shopping for a clutch a while back for my son, I looked at and found the Southbend units had the characteristics mentioned above. I'd take a look at those. (My son's car is motor stock so a "garden variety" JWT with nodular Fe flywheel suited that application best.)

Good luck with finding that tasty, edible cake to suit your appetite.
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Old 03-12-2018, 01:03 PM
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You know your input is always appreciated Mic. But I just wanted to throw it out there because I know with new tech clutches you don't need a 500lb pedal to handle 200hp like back only a few years ago.

At the same time I know some guys have been messing with organic twin discs and such to compensate for the slip n grab stuff. I just wanted to hear everyone's 2 cents before I went and threw money at the interwebs only to find out there is a better option out there.

That said, I have a general idea and have been giving Jim Wolf and some other twin disc clutches a look tho. But like I said I'd just like to see what our members are running and their trial and errors.
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Old 03-12-2018, 01:45 PM
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Originally Posted by CK_32 View Post
You know your input is always appreciated Mic. But I just wanted to throw it out there because I know with new tech clutches you don't need a 500lb pedal to handle 200hp like back only a few years ago.

At the same time I know some guys have been messing with organic twin discs and such to compensate for the slip n grab stuff. I just wanted to hear everyone's 2 cents before I went and threw money at the interwebs only to find out there is a better option out there.

That said, I have a general idea and have been giving Jim Wolf and some other twin disc clutches a look tho. But like I said I'd just like to see what our members are running and their trial and errors.
Absolutely. As I said, I have no experience with twins or puck clutches of current manufacture so it's of interest to me as well, if for nothing else than to know.

Just sayin' though, the tradeoffs are there no matter what car one is messing with, physics are physics and I kinda doubt that the new clutches - despite improvement over old - are able to deliver that desired cupcake soft pedal with the toughness of beef jerkey.

Would be nice to hear otherwise.
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Old 03-12-2018, 04:11 PM
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Originally Posted by MicVelo View Post
Absolutely. As I said, I have no experience with twins or puck clutches of current manufacture so it's of interest to me as well, if for nothing else than to know.

Just sayin' though, the tradeoffs are there no matter what car one is messing with, physics are physics and I kinda doubt that the new clutches - despite improvement over old - are able to deliver that desired cupcake soft pedal with the toughness of beef jerkey.

Would be nice to hear otherwise.
Seriously...check out the ATS across clutch specs.

http://www.ppi-ats.com/Carbon_clutch...ationlist.html

http://www.ppi-ats.com/Carbon_clutch...10_Nissan2.pdf

Red, yellow, green is their metric for clutch effort compared to stock.

I have a Spec I CN23280-14 which is RED and i love it with my RJM pedal. They have a similar spec II CN23H280-14s which is even softer on the leg. I had a Southbend DXD single clutch and it had a HEAVY feel even with RJM pedal.


Power Holding:

http://www.ppi-ats.com/Carbon_clutches/Spec_II.html

My clutch is rated to 740whp and so is the SpecII. Notice the column with the leverage factor.



Now when it comes to clutches, its a PICK 2...price, holding power, drive ability. I chose the latter. When i had an OS giken twin...i hated to drive my car.
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Old 03-12-2018, 09:29 PM
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I can't even find pricing on that terrible site lol

That thing looks like a circa 2002 web page lol

I don't mind paying up. But at the same time I don't think I need a $3,999 clutch for a car I paid $2,500 for haha
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Old 03-12-2018, 10:35 PM
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Originally Posted by CK_32 View Post
I can't even find pricing on that terrible site lol

That thing looks like a circa 2002 web page lol

I don't mind paying up. But at the same time I don't think I need a $3,999 clutch for a car I paid $2,500 for haha
2008.... close enough.

So is that how much they cost??

That's like the paint job costing me half the value (on a good day) of my car. Sure would look AMAZING but that hole in my wallet in which I've dumped green into, ehhhhh.
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Old 03-13-2018, 10:38 AM
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Hey Mic since you're here and I know you've talked about fly wheels in depth before.

I know Z's have a heavy mass fly wheel that helps with too end power. Would that even matter on a turbo application? Only thing I could MAYBE see it affecting is the spool. But a turbo application shouldn't be effected by a light weight flywheel right?

Possibly gain since it now has less mass for the turbo to push?
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Old 03-13-2018, 12:56 PM
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The website does suck.... Anyone have the part#/price for the twin disc??
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Old 03-13-2018, 02:08 PM
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Originally Posted by CK_32 View Post
Hey Mic since you're here and I know you've talked about fly wheels in depth before.

I know Z's have a heavy mass fly wheel that helps with too end power. Would that even matter on a turbo application? Only thing I could MAYBE see it affecting is the spool. But a turbo application shouldn't be effected by a light weight flywheel right?

Possibly gain since it now has less mass for the turbo to push?
Well, this is the Pandora's box enigma of running a turbo car.

First, look at the benefits of a LIGHTER FLYWHEEL: less weight hanging off the crank and therefore easier to rev and get you "into the power band".

Problem with that is that because it takes the load off the engine, the engine also LOSES revs faster than a heavier flywheel due to inertial forces. (You'll see why this is important below.)

Now compare that to how a turbo behaves. A turbo engine by itself, car out of gear, can be revved to 5k rpm unloaded and not build a quarter pound of boost pressure. Why? Well, never mind airflow dynamics for a second but this has to to do with pressure deltas INSIDE and OUTSIDE the engine, particularly on the intake side. Free revving barely budges a vacuum gauge yet, when in gear, under acceleration, you can watch the vac drop THEN as the turbo kicks in, go from negative pressure to positive.

That's because a turbo requires a load on the engine to work well. (Highly oversimplified.)

So, you drop some of the load off the engine and the turbo takes longer to build boost. Note I didn't say spool up. A lighter flywheel does little to change the spool up but to actually build the boost pressure, yes, this CAN AND WILL BE affected.

Also something to keep in mind is a lightened flywheel - as mentioned - drops revs in off throttle conditions quicker than a DMF or heavier single; thereby introducing more pronounced boost gaps (the loss of boost when shifting) requiring the turbo to build boost back up each time you shift. With a DMF or heavier single (up to a point) helps - through inertia - to keep load on the turbo, shortening the boost gaps.

This can have a big effect on power delivery. Not so much on a dyno because this isn't too much of a concern as the boost gaps are not so noticeable when you're pulling a single gear to get max power and torque readings. But driveability.... you will notice how "not smooth" it is as you row the gears up towards top gear.

Does this mean a HEAVY flywheel is "better"? No, not necessarily. The key is carefully matching the turbo and the clutch/flywheel assembly. There is an optimal weight for it given the type/size turbo and how it builds power. Exceed that weight or go too light and the turbo won't run as efficiently and will hit a point of diminishing returns - the base and height of the power curve as it were.

So what's the formula for determining at what weight your power transfer unit works best at? Well, to put it lightly, I've forgotten. Plus, none of my turbo applications (but one) were run in front of a manual trans. And that one with a manual ran a stock weight flywheel hanging off the back of the engine. (Oddly enough, it was that same engine, in normally aspirated mode (pre-build/turbo), that I learned to HATE lightened flywheels for street applications.)

But suffice to say that there will be a noticeable difference when pairing a given weight flywheel with, say, a big, laggy turbo versus that same flywheel paired to a high spinning small turbo (or set of turbos). This is why sequential delivery twin turbos are better with a manual trans than a single or twins feeding each bank. No gaps in power delivery because on throttle, there's boost throughout the power range. (Part of the reason I like supercharging so much. )

Does that answer the question?

I know it doesn't because the absolute answer to what works isn't present - but at least gives you some idea of the effect of too much/too little weight.
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Old 03-13-2018, 02:35 PM
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Nope that fully answered my question. My spool/boost build up is about perfect. And that's what I was thinking as well which is why it makes sense and answers my question well.

Which is why my turbo will go almost full boost when I'm in 5th or 6th and give it half throttle that massive load even at 2,500rpm spoils the turbo into full boost. Where's in first unless I go WOT I don't see a lick of boost all the way through the rev range.

That said I think my application would probably suffer from a lighter flywheel being it's about perfect where it's at now for drivability and WOT boost hits. Hell I still feel like I have a NA on daily driving. But the second I get into it it's a wild MF

I knew I asked the right guy. I was just hoping I was missing something and a LW fly wheel would aid in boost. But not in my case.

Remind me I owe you a beer sometime
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Old 03-13-2018, 02:51 PM
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You can get the clutch for around 2200 + shipping, import fee and nissan parts. 2400ish delivered.

As for the website...guess yall are more about glitz and glam. I listed the 3 pages you needed to know.

Like i said..price, holding power and driveability....pick 2.

People dont seem to understand what it takes to make a driveable car with big power. 3k clutch, 3k in fuel system, 3k in ECU and we have not even bolted on a turbo.
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