4.08 gears and Lightened Flywheel
 

I don't really see alot of talk on this mod. I found a few older threads 2009-2011.... Whats the verdict on this one?

Any long term issue's? Ample performance gains? I'd like to get as much feedback as possible on this.

Also the lightened flywheel I hear is a big improvement if you are already in there to do a clutch (Do we have a poor clutch life?).

The clutch is fine if you don't drive like a dumbass or throw a lot of power at it. The flywheel is a great upgrade, but a light flywheel usually makes a lot of noise and makes the car a little tougher to drive.

You'll spend more on labor to swap the flywheel than it would cost to upgrade the clutch too. Go ahead and do it while you're in there just don't go overboard with setup if you never intend to go FI. You buy the biggest clutch you can find you are going to hate yourself driving it around.

I upgraded my clutch a month prior to turbo build and I can definitely tell you there is no way I would volunteer to drive this clutch if it wasn't necessary.

If you're in there, get rid of the OEM CSC as well.

:iagree: Good catch. Of course than that leads to go ahead and replace the OEM CMC too since they appear to be one use items.

And this is the definition of slippery slope. Well since I'm in there...

Which clutch?

Went with the Z1 full face lightweight combo. It's reasonable except it sucks in traffic. I've driven worse but I would probably have to say it is at least 3-4x stiffer than stock with the help spring removed.

I'm ok with it considering I have to run it to hold power but I wouldn't if I was NA.

Interesting. I'm going with the same to go with my F.I. twin install. I have the helper spring which made a huge difference on the stock setup. Think I should remove it after the new clutch and fly?

soooo my clutch was slipping a bit at 70k miles and my csc blew so i decided to do it all in one shabang. I went with Comp Clutch clutch and light weight flywheel combo. I got it dynoed afterwards and there was no noticeable performance gain. You hear alot of talk from peoples butt dynos but those are the must unreliable and uncalibrated pieces of equipment. Flywheels have a little weight on them for a reason I was more or less just curious enough to do the swap. If i ever unbolt the tranny again I will be going back to the OEM flywheel. I ran at the strip with a buddy of mine too after the swap and we were both right around the same numbers in the 1/8 mile no big differences. Save your self the money IMO.

The flywheel isn't anything that will show up on the dyno or at the strip. It'll be a throttle response mod. Mine made a huge difference on throttle response at the cost of much noise. The weight is for noise control and to make it easier to drive.

Why does weight affect noise? That's unexpected.

Single piece flywheels rattle more than dual mass. The weight acts as a damper.

So back to the OP. I wouldn't have replaced my clutch, CSC, and flywheel if I wasn't going FI. I would have waited for the CSC to go out and spent the money on other things.

Can someone answer his question about the gears?

If you are used to driving with the spring in, then leave it in. I assume it'll help a little with peddle stiffnes.

I highly recommend the clutch. You definitely feel the differences with the ligthen flywheel. Revs much faster and throttle response is awesome. Like Chuck says, it's really noisy but you get used to it. When you drive off and your Z suddently sounds like a F250 diesel, don't be alarmed.:rofl2:

As for engagement. The Z1 clutch is slightly lower than the stock engagement point but it has a good window. I've driven some aftermarket clutches that were on/off switches, this one is nothing like that.

True but half The idea behind reducing the weight of the flywheel is that more torque will reach the wheels due to less rotating mass on the crank. Its just that most of the losses from crank power to wheel power occur in the gearing of the transmission itself. And your right the throttle response increase is due to the same reason because there is less weight on the crank. I notice it if the clutch is pressed the engine spools up quicker but again if im driving the time it takes to go from 2000 rpm to 7000 rpm probably hasnt changed. Idk for sure bc i havnt clocked it. All i really noticed is its sometimes annoying to start moving from a stop.

^ quoted your wrong post oops lol

I would assume the amount of power difference you'd see from a lighter flywheel would get swallowed up by dyno variation and air temp/density.

Yeah thats very true. Are you still glad you swapped? Since there was no track performance difference at the drag i can find no real way to validate the purchase. If my clutch is in i can rev faster but i dont notice a difference while racing so i ask myself is it worth it all the time. Eapecially at rush hour lol.

I like mine. The throttle response is markedly better now vs stock. I'd do it again. I'd probably go lighter since it's loud as hell now and I can't see it being too much worse. Is it worth doing if you've got a healthy stock clutch and the CSC hasn't failed yet? Probably not. If you're opening the transmission anyway? Sure.

Thanks for the replies, any word on the gears?

I agree with chuck on that if I take my tranny off again I'm going light as possible. Even with my steel south bend clutch flywheel it's really loud so if the noise is there might as well take full advantage.

I'm in for info on gears as well

I am looking at doing 4.08 gears when I do my LSD install soon. There seems to be some concern on it affecting syncro rev and I have been trying to get a straight answer about it before I pull the trigger and buy them.
But in theory and based on my tracking experience, I rarely see above 130 MPH on the tracks I do. Most of the time is spent between 3-4th gear, which would mean two things for me going to 4.08 gears:

1. I will have to shift a lot more.
2. I should gain a lot of my usable power band and should see a lot of benefit in terms of creating a "quick car" vs a "fast car"(high top speed).

For road racing, a quick car is always preferred to a car with high top end, unless you are doing circle track or topping out a lot in 5th(which I am not).

For drag racing NA, I would think the 4.08 gearing would be a huge improvement, but I don't drag race so I am just speculating.

So once I can get some solid feedback on the syncro rev problem, I am going to decide to buy them or not myself.

Good point on the Sync Rev. Hadnt thought about that.

I just ordered os giken lsd and only reason why I have not gone with shorter FD is the synchro rev too.. hopefully uprev can figure this out?

You will lose syncro rev functionality. When you go to down shift the rev match will be off by a couple hundred rpm. There is no way to get around this currently. In order for the rev match to work properly a constant hard programmed value for each gear is coded somewhere in the ecu. Since your final drive changes with a 4.08 swap your overal gear reduction changes and the constant coded value in the ecu is then wrong. Is it physically possible to change? It is if someone knew how to access the info in the computer. To my knowledge no one has been able to even find it much less modify it and this is the only thing that held me back from a 4.08 swap. I was so close to pulling the trigger but theres just something about knowing that a feature on my car doesnt work correctly whether i need it or not.

EcuTek is working on making synchro match work on 4.08 gears. I don't know if they finished it yet though

Yeah but theyve been working on it for years. I hope they make some progress soon.

Visconti claimed it was already possible with Ecutek, but there's been so much BS about ecutek it's damn near impossible to separate fact from fiction. SRM would overshoot the target rpm on the throttle blip, right? Hardly the end of the world if that's the case.

Srm would slightly undershoot target if final drive is changed so there is still a slight jerk after clutch is let out...but your right hardly that big of a deal for especially for purists who dont use srm. I like mine tho lol

Good discussion on the Gears. I want the extra jam, but I do not want to lose syn rev so I'm interested to see if there will be a solution.

If I were a vendor I could see this as being a good combo pack, gears and a Syn rev tune sold together.

Yes on this chuck , but I have also heard that although the overshoot is not bad, and that by raising the rev limiter by about 300 rpm it will essentially eliminate the issue. I have also heard that unfortunately the ECU starts to figure out that it is "missing the mark" so to say and can actually cause some other problems. It gets pretty vague at this point, and is all hearsay as far as I am concerned.

The ECUtek solution, yeah don't hold your breath.

Yeah I am looking at a decent set of pedals as a "real" solution. I completely hate our pedal configuration, the throttle is too far back and too narrow imo.

I want to go lighter flywheel myself for throttle response, but also because I feel like when I shift, I have to shift slowly so the RPM's will drop enough for a smooth engagement. Will a lighter flywheel drop RPM's faster too?

The light weight fly wheel will drop RPM quickly due to less rotational mass.

Just got my Nismo back from Zspeed with the Z1 clutch and lightened flywheel, plus the Zspeed CSC. All I can say is WOW. The Z just feels more alive and shifting is so much better IMHO. Also the feel of the clutch is so much closer to what I think it should have been from the factory.

Sub'd

I noticed quite a bite of improvement with a lightened flywheel. Both in the lack of surge in first, and muuuccchhh better throttle response. It's a bit chattier than the oem, but honestly not much. I had the southbend 12lb flywheel and the endurance disk/pp.

As got the gears...if you're staying n/a it's great, but you will likely lose s-mode functionality. If you plan in boosting the car, for gods sake don't go with 4.08 gears. Go taller if anything.

And go ahead and get the RJM clutch pedal. The helper spring is good, but nowhere near the RJM setup.

Just throwing it out there ill switch any boosted member my AT Pumpkin (3.3) for your MT Pumpking witb 3.69s:bowdown: