Background: As some of the SoCal folk know, my 04 coupe clutch felt exceptionally worse than most stock clutches. It engaged higher than normal and had a very “spongy” feeling when you steep on it. After talking to Dru (meechin) and taking his sexy ride for a spin, I decided I needed a new clutch for sure. Dru is rocking the JWT clutch and UR flywheel. I loved it; however the chatter at low RPMs bothered me, so I decided to go with just a new clutch with stock flywheel.

Install: As stated above, I took my car to Street Image for just a clutch install. However, after dropping my tranny, they concluded that I would need a new flywheel to pair with the new clutch since my stock fly had a lot of wear on it. I blame Ed (G35lin) for abusing my poor car (just kidding ed haha). Anyways, since the UR flywheel is quite rare and takes a while to come in, I went with the JWT flywheel since Street Image could get it that day.

Impressions: As expected the car is a dream to drive now. It feels like the front of the car shed off 150 pounds. Gears 1 through 3 pass a lot faster. As expected, it is more of a “weight reduction” feeling than a “more horsepower” feeling. Engine breaking is less severe and it’s smoother now. The clutch engagement point is extremely low, but I am told it will rise a bit as the clutch gets broken in. As the clutch pedal is released, it feels very linear and is way lighter than before, but still not as light as Dru’s clutch pedal (no clue why). Rev matching is much easier with the lighter flywheel, and mismatches are much less violent. On the bad side, I get chatter when in gear and giving it gas under 2200 RPM. With some music on at a reasonable level, you can’t even hear it from within the cabin. Very little chatter at idle. So little that idle chatter is a non issue. No chatter in reverse.

Stuff you should know:
I am VERY picky about squeaks and rattles in my car. The flywheel doesn’t really bother me since I expected it to be a little noisy, and I accept it as the price to pay to play. A light weight flywheel is NOT for people who are very picky about noise.

For those who do want a new combo, but want to minimize chatter, go with a JWT clutch and UR flywheel. The UR rattles under the same conditions as my JWT flywheel, however the chatter ends much sooner at around 1600 RPM. The UR piece is more expensive, however it is better made, and rattles a bit less. Most of the guys with the JWT flywheel complain about noise at idle, and don’t really mention chatter under acceleration under 2200 rpm.

Overall: GREAT mod, and definitely one of my favorites. The chatter sucks, but that is the ONLY downside. Somebody REALLY needs to build something to keep the throw out bearing from rattling against the flywheel!!!!

A big thanks to ed, Street Image Eric and Mondo for their flawless work, Dru for letting me try out his setup and for dealing with my flip flopping, and everybody else who gave me their input on their setups. If you have any questions regarding any of my mods, feel free to PM me or catch me on AIM.

 

Nice review. So does the car actually accelerate faster or is it just as "feeling". How much did the whole setup run you?

 

Thanks for the review. What's the mass reduction with the UR flywheel? We can calculate really quickly how much "faster" the car is. What do you mean by the flywheel "rattles"?? It rattles all the time, or only under engagement?

 

what's the cost breakdown for thoses who might be interested?

 

The car accelerates much faster. By the feeling I meant it felt faster in terms of weight reduction as opposed to more power. ehh does that make sense?! haha

I am not sure how much lighter the UR flywheel is. It’s a smidgen lighter than the jwt fly which is 14.3 lbs vs the stock 23lbs. I don’t think that this mod will show up on a dyno, but I believe it does yield results on the road.

The rattle sound is just a louder version of that ugly noise that some of us get when we shut off the engine in neutral without the clutch engaged. It is the sound of the throw out bearing rattling against the flywheel. I actually will be in the bay area next weekend so if you are really interested in hearing it we can meet up. It rattles when the clutch is engaged under 2200 rpm.

The cost will vary depending on where you go, but both the clutch and flywheel should be around mid to low 400s each. I believe the UR flywheel is around 5-600 bucks. Install depends on where you go also, but expect to pay another 3-400 if not more depending on the shop.

 

It'll show up in a reduced state on any transient dyno (Dynojet, Mustang, etc), but gains on the street will be most noticeable in 1st and 2nd gears. Any idea what the flywheel diameter is offhand?

 

well according to i-m-racing the nismo fly is for 7.25 inch clutches, so i am assuming this is the same for the jwt. i could be totaly off though.

 

Alan, is there any start-up noise??? I had the JWT combo(1200kg clutch) in my other VQ and it sounded awful at start up. JWT Tech guy told me "it's normal" but it sounded like it was missing the flywheel (grinding kind of) but it worked fine. I just didn't like the start up noise. Is it present for this set up?? I hope not, because that combo was great, but sucked for the tires!!!! LOL

 

Alan, How many miles did you have on your car when you switched out the clutch? I too have a clutch pedal that engages at the high end of travel, but the car only has 19,000 miles .....and still grabs strong

 

I would imagine that there would be little to no gains on a HP vs. RPM plot, but RPM vs. Time would likely show some improvements, as the lower mass allows the motor to rev more freely (faster). This would result in a faster vehicle.
Same idea w/ lightweight pulleys.

 

A great write-up, Alan. Thank you for the future reference.

 

OEM Flywheel (dual mass) is actually 28lbs.
NISMO FW = 23lbs
JWT/UR/STILLEN=14.3lbs (around that area)

OEM Clutch weighs in at 19lbs
JWT Clutch = 19lbs
NISMO = 16lbs

As for diameter, they should all be very close to one another.
The only one that noteworthy of being much smaller is the Tilton setup.

You'll learn to deal with the chatter.
IMO, definitely worth the trade off for the added PUNCH.

POB
DRU

 

i dont experience any startup noise. in fact the flywheel makes almost no noise when the engine is fairly cold.

i had 30k miles when i got the clutch and fly. keep in mind i switched it because i did not like the feel of the clutch, not because it was worn out.

Dru, thanks for the additional info.

 

On any dyno where the car is accelerating (that is, the engine is not being held at a steady-state RPM and the power measured at discrete points), such as Dynojet or Mustang dynos, any reduction in parasitic inertia will show up as "gains" on the dyno. When the engine is accelerating, it has to accelerate the flywheel as well, and if it now has less inertia, less power is spent accelerating it, and more will appear at the wheels. The gains are highest when engine acceleration is highest. The gains are proportional to the gear ratio squared, so highest gains are in 1st, then 2nd, and diminish heavily in the higher gears. If you're intersted in this you can check out a write-up I wrote here: http://www.stanford.edu/~mpg/lighten...omponents.html .

Anyway, 7.25 inches sounds WAY small for a clutch! Anybody know the outer diameter of the flywheel offhand? I was just going to run some quick numbers on percentage gains in 1st / 2nd / 3rd / etc for the lightened flywheel.

 

well i have the stock flywheel sititng in my car. ill let you know what the diameter is once i get my hands on a ruler.