Halon

iTrader: (6)

I'm going to start this off with saying, please do not reply with things like "the w58 will break", I'm not interested in any of that. This is a custom application.

I've contacted numerous different clutch manufacturers about their clutch offerings for the w58 style transmission arrangment. Everyone from ACT, Clutchmasters, Spec, Centerforce, etc... Nobody seems to make an off the shelf clutch setup that can hold any real torque. ACT's strongest option is only rated to 450tq, and that's with their "EXTREME Pressure Plate and a pucked disc". That makes sense considering the trannies can't hold much, but again I'm not interested in that. I'm interested in a clutch that has a tq rating in the 550-600tq rating. One big reason that none of these clutches really hold much torque is because the clamping force is pretty low. The highest off the shelf offerings are around 2200lbs.

Right now, I'm running a custom setup with a 350z clutch in my SC, with a CD009 trans. It's a JWT clutch that is marketed as being 2650lbs clamping force. The pedal is stiffer than normal, but not too bad. And that was on all the stock hydraulics.

I also came from the DSM world where I ran ACT 2600 and 2900 clutches in my cars. Definitely stiffer pedal than stock, but it wasn't a big deal. Again, ran on the stock hydraulics.


So that's some of the back story. I'm going to be running a custom setup where I want to use a W58 style clutch. But I need something that can hold torque. So I was able to get ahold of a manufacturer that said they would be willing to make me a custom pressure plate with higher clamping force. Based on the fact that I am currently running a 2650lb clutch, and have ran 2600 - 2900 in my DSM's, I shared that with them and said if they were able to get it to clamp in the 2700 - 2800 range, that might work out good for me. They said OK will do.

I received a call from them yesterday. They said they finished the pressure plate, and they measured it on their scale and it was right at 2700. They also went to another manufacturer and double checked the force on their scale and it also said 2700. Great right! No they said. They are saying that clamping force is so much, that it looks like it's bending the pressure plate. They said the clutch pedal will be ridiculous, and it might be too much for the stock hydraulics. They said the force is so high it might actually rip the bolts out of the aluminum flywheel.


So, I'm a little bewildered. Hoping there may be some drivetrain gurus here that might be able to put in some good 2 cents here. I'm glad they called me and told me about all of this, but I'm very confused. I explained to him that's barely more clamping force than what I have right now (2650 vs. 2700). And explained to him how I've ran even heavier clutches before in my DSM's. So I'm just really lost as to how this 2700lb setup would be so ridiculously heavy.

One explanation he said is that a lot of clutch companies market their clutches at "X" clamping force, but aren't actually that much. But he did say ACT's stuff is usually pretty accurate. So none the less, I'm going to send him my current JWT 2650 pressure plate. He's going to measure it on his scale and see what it says for comparison since I said it's working fine with my hydraulics. And we'll go from there.

But wondering from other folks on here that know a lot about clutches, does this make any sense? I'll also note this is a push setup (not pull like say a R154). And my DSM clutches and 350z clutch are also all push type clutches.

Ali SC3

iTrader: (10)

Yeah there is something odd about the w58, I thought it was the push vs pull but the dsm stuff is an interesting counterpoint to that.

I can tell you I have the act extreme with the 6 puck sprung clutch, and the clutch pedal is ridiculous.
every person who gets in my car stalls or does a burnout by accident.
also, if you let your foot off the pedal accidentally and it slams into gear, it engages so hard I feel like I destroy part of the crank whenever it happens, I would not be surprised if it crank walks some day.

so in short yeah, I don't know why they can't hold more power but I can say 1000% you do not want a pressure plate stronger than the act extreme, if just for the crank's sake.

I have often wondered why they don't offer a good twin or triple disc clutch that can hold more power with less clamping force, but at the end of the day it seems the trans wont hold that much more power so its a gamble.

Halon

iTrader: (6)

Well that is very interesting thank you. And extremely confusing because it's only a 2200lb pressure plate supposedly. My DSM was a push style, my current 350z clutch I was running was push style also at 2650lbs. I guess the pivot point or something must just be completely different or something?

Now I'm no clutch guru, but your comment about crank walk. Is it clutch pedal effort, or total clamping force, that has a larger role to play in crank walk? For example, If right now I'm running a 2650 clutch with not so bad of pedal effort, or a supra guy with a with a 3000lb+ pull type with a somewhat heavy pedal, or you with a 2200lb clutch with a ton of pedal effort. Again I'm not expert, but in my mind just because you have a lot of pedal effort, I figured the clamping force is the main thing that would contribute to that, not pedal effort. Clamping force is the actual force placed upon the drivetrain/motor. Pedal effort is nothing more than a result of hydraulics, pivot points, etc.

Ali SC3

iTrader: (10)

Well I am assuming the stock SC hydraulics, and the clamping force just seems excessive for holding 400tq (whatever the differences are from) and I think that is what is causing the pedal effort. We know people run the same hydraulics on the r154 and other transmissions and it seems setups that hold similar power have less pedal effort. Its not the pedal effort that bugs me though, its that the clamping force is so hard that the few times I have had my foot slip off the clutch its like it violently slams into the motor, it doesn't just wind to a stop I can feel it reverberate throughout my whole back (its only happened like 3-4 times ever but every time I wonder if it will start again its that bad).

this page kinda touches on the topic
http://www.motoiq.com/MagazineArticl...et-a-Grip.aspx

it says that pull has a lighter pedal feel than push with the same load, and the way the pull type works it applies 30% more clamping load than push... I dunno too much push vs pull its all jumbled in my brain now.

I think its saying for the w58 to hold as much as the r154, the w58 would need 30% more clamping force which would likely bend the cover as you confirmed by talking to the clutch people, and the pedal would be much stiffer due to the fulcrum not being as optimal. so it sounds like it is a push vs pull thing. maybe the DSM's have stronger hydraulics?

Halon

iTrader: (6)

So where I'm baffled is in my SC300, I have (well had) a PUSH style 350z clutch setup, on stock SC300 hydraulics (exception being I had a stock 350z slave), that's 2650lbs clamping force, and my pedal is nothing crazy.

DSM stock hydraulics aren't anything crazy fancy. And they worked fine on my 2600 and 2900 setups, again PUSH style.

I guess I just need to re-evaluate my clutch setup now. Because there must just be something very different about the SC / IS flywheels that make them incapable of much higher than 2200lb clamping, that is beyond my knowledge of clutches.

Ali SC3

iTrader: (10)

the only other insight I can give you is that the W58 is like the 20th revision of an original G series box designed originally to hold about 40tq. Even though its the latest and greatest of those line of boxes, I think its still limited by its original design that probably goes down all the way to fulcrum points, fork, bunch of small stuff I would say adds up and makes a difference. I am not an expert as you know and it sort of evades me the real truth to it but its nice to have a discussion about it and try and get down to some facts.

those newer boxes like the 350z were designed for lots of power from the start, and I want to say the 350z uses a larger diameter clutch disc but I am not positive. I know the v160 does, but the r154 has the same size as the w58 so again that is confusing I know. I think it also comes down to the design in addition to the pull push thing, and the SC with a turbo is pushing the limits of what it can do in every way it seems.

Halon

iTrader: (6)

The manufacturer that made this clutch tested the clamping on a test bench, with a scale. And he is reporting how insanely heavy it is. I'm just assuming here, but I do not think he is using SC hydraulics, or an SC slave, or a w58 clutch fork, etc. to test this. They have a scale that they use to measure it. I'm assuming it looks something kind of like this, with just the clutch / flywheel components being tested all on their own.



So they are seeing that this is extreme with the components all by themselves, nothing with the rest of the car/system.

None the less, even if I can't understand it, I think they are right based on your feedback that your 2200lb plate is really stiff. It just confuses me how that is, but maybe I'll just be forever confused about it

Ali SC3

iTrader: (10)

True, but maybe they are just being overly cautious though, It might not be too much for the hydraulics but it might be too much for a streetable car.. and you can always use the stock flywheel which should hold up.

If you ever are in the colorado area, feel free to stop by and you can see how terribly stiff and high clamping mine feels like.. and the joke is it can only hold 450tq.
That is pretty much the reason I want to pull it and upgrade, because at stock power it was a good transmission, but with turbo power the clutch options are all just very bad.

my brothers supra with the v160 on a stock clutch can hold similar, and his clutch feels like the softest clutch ever and it slips so nicely (mine does not "slip"), it basically feels like my stock sc300 used too with stock everything. I know the clutch is a little larger diameter, but seriously there must be more to it than that.

So I think there is something more to this whole pull vs push thing. I didn't realize the 350z was a push style, that kind of bothers me but you said it feels alright, so it must be some changes they made to make it havae a more reasonable pedal feel than the run of the mill push style boxes.

*Edit* just thought maybe there is something to the actual pressure plate design also, because I learnt that toyota uses the same pressure plate pattern/cover on lots of push type clutches up to a certain year, like the 5m and 7m and the 3vze share the same clutch cover as the 2jzge, even though the 3vz uses a r150 it uses that pattern cause the r150 on the trucks are push type. the 5vze uses the same pattern also but has a larger clutch disc and flywheel friction area.
The r154 uses a different clutch cover bolt pattern (so they cannot be mixed up) and I think they did that just cause they knew it would hold more power with a better clutch feel.

So maybe part of the weakness is that they are using a design that they use on lots of other older cars that they keep retweaking, as in the pressure plate design itself cannot handle that much more clamping force.
I bet the 350z one is beefed up alot, and they factored in the extra power from the get go in all the components even though its a push style.
The DSM's came with a turbo motor right, so maybe they factored that in to the pressure plate design.

I might have missed it, but the pressure plate you asked them to upgrade to 2700, was that the 350z PP or the 2jzge PP, I was thinking the 2jzge PP for some reason.