JWT Clutch + Flywheel Review
04-10-2007, 06:58 AM
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JWT Clutch + Flywheel Review
Hey Everyone,
Just had my JWT Clutch + Flywheel combo installed. Actually, I had it installed a couple months ago, but I've just now got around to driving with it, since the weather is finally improving. Anyway, I thought maybe I should give my impressions since so many people seem to be considering this setup, and yet I have only found a small handful of reviews. Which probably is good enough.. But anyway-
I have a 2004 Roadster, Touring, in Silverstone, just under 25K miles. Prior to this mod I swapped the stock CAI for an HKS model, which I wound up running short because the full setup routed the intake all the way under the bumper, which made me nervous just thinking about it- lots of rain and potholes around here. Anyway, realizing that the stock CAI is plenty good enough, and that a popcharger probably would provide better gains (+2 HP vs +0 HP
), I wouldn't have even bothered, but the guy threw it in with the exhaust I was buying for an extra $25. Which brings me to the only other mod that I have, a Borla True Dual exhaust. Yes, I know that neither mod is anything to write home about, and I certainly wouldn't have bought either new- I think the Borla is found for like $900 new and the HKS for an outrageous $400 (ballpark)- but I got a decent deal, I think- $550 for both, used but in very good shape.
Since this is supposed to be a review for the clutch and flywheel, I guess I shouldn't write too much about the intake or exhaust, but a little bit of insight could be helpful for making comparisons, right? The intake didn't do much of anything performance wise, which is expected, but it did produce a noticeable change in the intake sound, very noticeable at around 5-6K RPMs, where there is a huge, ferocious grunt, and, maybe, a couple extra ft-lbs of torque- can't say for sure, it could just be psychological. I haven't dyno'ed it. But that's about it for the intake. The Borla didn't change the exhaust note very much, which I was happy with since I like the sound of the stock exhaust. It is definitely boomier at low RPM's, and seems to amplify the roar that the HKS added at 5-6K RPMs and up. But other than that, not much difference sound wise IMO. HP wise, I can definitely feel some extra pull above 5K RPMs. Nothing dramatic, maybe 5 HP. Maybe 10, I don't know. Point is, not a big difference performance wise from either mod, totaling $550 for me used and probably close to $1200 or $1300 new.
So, now the JWT combo. I paid around $900, brand new and w/ rush shipping from Concept Z Performance. My experience with them was great by the way- couldn't find a better price anywhere and great customer service.
Got the parts, got them installed for about $350, bringing the total cost to about $1250. I drove the car home (stalled it out twice- the clutch is pretty grabby at first- but I'll get to that later), and left it in the garage for a couple months. Finally a couple weeks ago it warmed up around here and I started breaking it in. So, for the first 500 miles-
Breaking in the clutch was an exercise in patience. Staying under 3K RPMs for 500 miles was tough, but I did it anyway and so my impressions during this initial period were limited. My very first impression was that the the pedal feel had changed significantly, with the clutch grabbing right off the floor. I got used to it quickly though, and by the time 500 miles or so had passed, it loosened up considerably. Still grabs sooner and faster than stock- both good things IMO- but is now much more suitable for daily driving, having been broken in. So without sacrificing much in the way of streetability, you get a more quicker, tighter, more direct clutch feel. Makes it feel.. sportier.
After the pedal feel, the second thing I noticed was the difference in shifting. The lighter flywheel means that smooth shifting- whether up or down- requires more attention and more precise throttle control to match revs. The decreased flywheel inertia is immediately apparent, and the best way I can think of to describe it is that the car feels jumpier, or jerkier, but in a good way- much sportier. Not necessarily faster, not while I was stuck under the 3K ceiling anyway, but more twitchy, more edgy, more responsive, and just plain sportier. While the stock flywheel was heavier, had more inertia, and also had an 'inertial flywheel' mechanism- please correct me if that's not the right terminology, but my understanding was that it had a way of maintaining its inertia to provide smoother, easier shifts- the JWT is lighter and requires more effort and concentration to match revs (since it both gains and loses revs much more quickly), but the reward is a flywheel that gets to whatever RPM you want to spin it at quickly, responsively, and accurately. I feel much more directly in control of the tach needle, and much more connected with it. More integrated into the car, more sporty, more fun. Did that make sense? Hope so..
The final evaluation I tried to make while breaking the clutch in was the acceleration. After all, that is probably the main reason most owners would consider upgrading their clutch/flywheel in the first place- improved acceleration (maybe the top reason is more clamping force to handle FI, N2O, whatever.. but I'm still NA and probably haven't even broken 300 HP so I really can't evaluate clamping force- nor does it matter to me). I would have to say that I was a bit disappointed at first. Off the line, not much improvement acceleration wise, maybe somewhat but if it is there, it's small enough that I can't really tell if I'm imagining it or not. Approaching 2K and then 3K RPMs, I can feel the car starting to pull a bit harder than normal- definitely not imagining it there. Unfortunately when I get to around 3K it's time to shift anyways- still breaking in the clutch. At this point I am disappointed because I imagined most of the improvement, acceleration wise, would occur during the first few thousand RPMs. Not quite sure why I thought that. I guess I figured that the reduced rotational mass would have a greater effect at lower RPMs rather than higher. Kind of like pushing a car- it's really hard to get it moving, say from 0 to 3 mph, but then from there it's easier to get it going from 3 to 6 mph. At any rate, I was wrong.
Once I put about 500 miles on the new clutch, I gradually started giving it more. By 600 miles I finally had the nerve to redline it. And that's when I realized how wrong I was. There is a drastic improvement in acceleration once you hit around 4K RPMs. From the torque peak at 4800 RPMs all the way to redline is an absolute blast. I would swear the car was turbocharged the way the tach needle sprints through the last 2-3K RPMs (then again I've never been in a turbo'ed Z, but I'm just making a point). The JWT combo knocked about .5-.6 off my 0-60 mph time. It's amazing.
So yes, I was wrong initially about the acceleration; this mod is well worth the money IMO; the point I was making with the intake/exhaust earlier is that for about the same money, I got a much, much better performing modification with the clutch/flywheel. Wish I would have known, I would have skipped the intake/exhaust and done the JWT combo first. All in all, my Z is quicker, sportier, and most of all, more fun to drive. For the price, probably one of the best mods you can get. A no-brainer in my book. I hope this review was helpful. Thanks for reading the ridiculously long post guys!
-Dino
Just had my JWT Clutch + Flywheel combo installed. Actually, I had it installed a couple months ago, but I've just now got around to driving with it, since the weather is finally improving. Anyway, I thought maybe I should give my impressions since so many people seem to be considering this setup, and yet I have only found a small handful of reviews. Which probably is good enough.. But anyway-
I have a 2004 Roadster, Touring, in Silverstone, just under 25K miles. Prior to this mod I swapped the stock CAI for an HKS model, which I wound up running short because the full setup routed the intake all the way under the bumper, which made me nervous just thinking about it- lots of rain and potholes around here. Anyway, realizing that the stock CAI is plenty good enough, and that a popcharger probably would provide better gains (+2 HP vs +0 HP
), I wouldn't have even bothered, but the guy threw it in with the exhaust I was buying for an extra $25. Which brings me to the only other mod that I have, a Borla True Dual exhaust. Yes, I know that neither mod is anything to write home about, and I certainly wouldn't have bought either new- I think the Borla is found for like $900 new and the HKS for an outrageous $400 (ballpark)- but I got a decent deal, I think- $550 for both, used but in very good shape. Since this is supposed to be a review for the clutch and flywheel, I guess I shouldn't write too much about the intake or exhaust, but a little bit of insight could be helpful for making comparisons, right? The intake didn't do much of anything performance wise, which is expected, but it did produce a noticeable change in the intake sound, very noticeable at around 5-6K RPMs, where there is a huge, ferocious grunt, and, maybe, a couple extra ft-lbs of torque- can't say for sure, it could just be psychological. I haven't dyno'ed it. But that's about it for the intake. The Borla didn't change the exhaust note very much, which I was happy with since I like the sound of the stock exhaust. It is definitely boomier at low RPM's, and seems to amplify the roar that the HKS added at 5-6K RPMs and up. But other than that, not much difference sound wise IMO. HP wise, I can definitely feel some extra pull above 5K RPMs. Nothing dramatic, maybe 5 HP. Maybe 10, I don't know. Point is, not a big difference performance wise from either mod, totaling $550 for me used and probably close to $1200 or $1300 new.
So, now the JWT combo. I paid around $900, brand new and w/ rush shipping from Concept Z Performance. My experience with them was great by the way- couldn't find a better price anywhere and great customer service.
Got the parts, got them installed for about $350, bringing the total cost to about $1250. I drove the car home (stalled it out twice- the clutch is pretty grabby at first- but I'll get to that later), and left it in the garage for a couple months. Finally a couple weeks ago it warmed up around here and I started breaking it in. So, for the first 500 miles-
Breaking in the clutch was an exercise in patience. Staying under 3K RPMs for 500 miles was tough, but I did it anyway and so my impressions during this initial period were limited. My very first impression was that the the pedal feel had changed significantly, with the clutch grabbing right off the floor. I got used to it quickly though, and by the time 500 miles or so had passed, it loosened up considerably. Still grabs sooner and faster than stock- both good things IMO- but is now much more suitable for daily driving, having been broken in. So without sacrificing much in the way of streetability, you get a more quicker, tighter, more direct clutch feel. Makes it feel.. sportier.
After the pedal feel, the second thing I noticed was the difference in shifting. The lighter flywheel means that smooth shifting- whether up or down- requires more attention and more precise throttle control to match revs. The decreased flywheel inertia is immediately apparent, and the best way I can think of to describe it is that the car feels jumpier, or jerkier, but in a good way- much sportier. Not necessarily faster, not while I was stuck under the 3K ceiling anyway, but more twitchy, more edgy, more responsive, and just plain sportier. While the stock flywheel was heavier, had more inertia, and also had an 'inertial flywheel' mechanism- please correct me if that's not the right terminology, but my understanding was that it had a way of maintaining its inertia to provide smoother, easier shifts- the JWT is lighter and requires more effort and concentration to match revs (since it both gains and loses revs much more quickly), but the reward is a flywheel that gets to whatever RPM you want to spin it at quickly, responsively, and accurately. I feel much more directly in control of the tach needle, and much more connected with it. More integrated into the car, more sporty, more fun. Did that make sense? Hope so..
The final evaluation I tried to make while breaking the clutch in was the acceleration. After all, that is probably the main reason most owners would consider upgrading their clutch/flywheel in the first place- improved acceleration (maybe the top reason is more clamping force to handle FI, N2O, whatever.. but I'm still NA and probably haven't even broken 300 HP so I really can't evaluate clamping force- nor does it matter to me). I would have to say that I was a bit disappointed at first. Off the line, not much improvement acceleration wise, maybe somewhat but if it is there, it's small enough that I can't really tell if I'm imagining it or not. Approaching 2K and then 3K RPMs, I can feel the car starting to pull a bit harder than normal- definitely not imagining it there. Unfortunately when I get to around 3K it's time to shift anyways- still breaking in the clutch. At this point I am disappointed because I imagined most of the improvement, acceleration wise, would occur during the first few thousand RPMs. Not quite sure why I thought that. I guess I figured that the reduced rotational mass would have a greater effect at lower RPMs rather than higher. Kind of like pushing a car- it's really hard to get it moving, say from 0 to 3 mph, but then from there it's easier to get it going from 3 to 6 mph. At any rate, I was wrong.
Once I put about 500 miles on the new clutch, I gradually started giving it more. By 600 miles I finally had the nerve to redline it. And that's when I realized how wrong I was. There is a drastic improvement in acceleration once you hit around 4K RPMs. From the torque peak at 4800 RPMs all the way to redline is an absolute blast. I would swear the car was turbocharged the way the tach needle sprints through the last 2-3K RPMs (then again I've never been in a turbo'ed Z, but I'm just making a point
). The JWT combo knocked about .5-.6 off my 0-60 mph time. It's amazing.So yes, I was wrong initially about the acceleration; this mod is well worth the money IMO; the point I was making with the intake/exhaust earlier is that for about the same money, I got a much, much better performing modification with the clutch/flywheel. Wish I would have known, I would have skipped the intake/exhaust and done the JWT combo first
. All in all, my Z is quicker, sportier, and most of all, more fun to drive. For the price, probably one of the best mods you can get. A no-brainer in my book. I hope this review was helpful. Thanks for reading the ridiculously long post guys!-Dino
Last edited by the rainman; 04-10-2007 at 07:03 AM.
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04-10-2007, 10:41 AM
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04-10-2007, 12:26 PM
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thatd be purdy nifty. somebody with a stock 06' needs to go run a 1/4 mile with the JWT clutch/14 lb flywheel and see how much quicker theyre runnin.
04-10-2007, 11:38 PM
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Great review!! I'm definitely thinking of getting the JWT combo.. Any idea how this compares with an ACT combo? is it the difference between daily and track? I want performance and durability, but my 350z is a daily driver so I don't want it to be a b1tch to drive all day..
04-11-2007, 10:18 AM
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thats def alot faster than stock. stock theres lag from 750 rpm to about 3k stock, and even from 3k to redline its still kinda laggy. with yours tho no lag, just rev.
Last edited by ke0ki2k; 04-11-2007 at 12:44 PM.
04-11-2007, 11:11 AM
#20
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I stopped reading at "The Borla didn't change the exhaust note very much...". Nonsense...or you need a hearing aid. 
j/k. Thanks for the writeup. Always nice to hear diferent experiences.
j/k. Thanks for the writeup. Always nice to hear diferent experiences.