here is how to do the math...

i worked out the math in a thread...

I did this for the AT guys....


Ok here are my calculations on the gears:


1st - 3.540
2nd - 2.264
3rd - 1.471
4th - 1.000
5th - 0.834


Stock Tire Size 245/45/18 = Revs Per Mile = 756

FD = 3.3
FD = 3.538
FD = 3.700
FD = 3.917


Formula:

RPM / FD Gear Size / Tire RPM x 60 = Speed in MPH


RPM:

3000 RPM in 4th Gear:

3.3 @ 3000 RPM = 72.15 MPH
3.538 @ 3000 RPM = 67.29 MPH
3.700 @ 3000 RPM = 64.35 MPH
3.917 @ 3000 RPM = 60.78 MPH

3.3 @ 6000 RPM = 144.30 MPH
3.538 @ 6000 RPM = 134.59 MPH
3.700 @ 6000 RPM = 128.70 MPH
3.917 @ 6000 RPM = 121.57 MPH

Forumla for other gears:

RPM / (FD Gear Size x Tranny Gear Size) / Tire RPM x 60 = Speed in MPH


3000 RPM in 5th Gear:

3.3 @ 3000 RPM = 86.51 MPH
3.538 @ 3000 RPM = 80.71 MPH
3.700 @ 3000 RPM = 77.17 MPH
3.917 @ 3000 RPM = 72.90 MPH

3.3 @ 6000 RPM = 173.02 MPH
3.538 @ 6000 RPM = 161.42 MPH
3.700 @ 6000 RPM = 154.35 MPH
3.917 @ 6000 RPM = 144.21 MPH


6200 RPM in 1st Gear:

3.3 @ 6200 RPM = 42.12 MPH
3.538 @ 6200 RPM = 39.30 MPH
3.700 @ 6200 RPM = 37.56 MPH
3.917 @ 6200 RPM = 35.48 MPH




The 3.7 gear set works with any rear end that will work with the 3.5 or 3.9 gear set...

So, basicly all you need is a 3.5 6MT pumpkin w/ VLSD or can be used with any Aftermarket LSD that works with the 3.5 gear set...

THe 3.70 gear set is: $480 for the gear set alone... You will also need the same pinion nut, pinion seal, spacer housing, bearing, etc etc just like with the 3.5 gear set...

to date ive done half a dozen of the 3.7 gear sets into auto's...

 

could just go here and plug numbers in

http://www.f-body.org/gears/

 

Thanks for all the numbers and stuff above; I'm quite familiar with what the gears do and RPM/speed differences from stock, though. This is just a discussion comparing the benefits of the gears to that of a heavy duty clutch, lightened flywheel and which mod is the beat bang for the buck/should I do fist, given what I want.


Ok, well here's what I'm planning:
I've got a plenum mod and other breathers that help top end power and I'm planning to do TS reflash to tune and raise rev limiter.

I WANT the car to accelerate faster. I like the feel of the stock clutch and I'm not hard on it. The RPMs could drop a little faster for my taste, though; I know this is the flywheel issue. I rarely drive my car above 5k RPMs, so I doubt that having the 3.9 gears would be a boon to me on my 187 engine; daily driving I upshift around 3-4k, and I doubt doing it 10% higher with gears will be an issue.

I'd LIKE to eventually do both mods; just wondering which I should do first.

As for cost, JWT combo is $769 and Central 20 3.9 gears run what, $500? Looking at what, around $400 to install either?

Looks like the UR flywheel is 1lb lighter than the JWT and a couple hundred bucks more... What kind of noise are we talking with the JWT?

I need the car to be very streetable, though; ability to start off easy in stop and go traffic is a must, so Tilton sounds like it's deff. out.

Can you try and explain this a little differently? I'm not sure I follow what you're trying to describe here. Is this in reference to starting from a stop and by disengage, do you mean push the clutch in or let it out? With stock, I just apply a very little throttle and slowly let out the clutch. In stop and go traffic, I can do this, then completely let off the throttle and the car will idle forward in 1st gear like an AT; will I still be able to do this with the JWT package?

 

I say UTEC & tune. You are most likely running dangerously lean and a UTEC will help richen you up and free up some extra power.

 

i can give you a ride in a tilton car. if you ever in the torrance area let me know. i love the tilton. sad thing is they dont make it anymore. so i feel im gonna hate the jwt after this clutch wears out. the rev charactaristics are unmatched.

Hammad

 

The stock clutch lets out up top, once I got my car back with the JWT combo it let out at the floor and has better response. I am pretty sure that is what he meant. It also is not as stiff as the stock clutch set up.

I also have popcharger and AAM spacer and love the combination of all parts. You can't go wrong with JWT clutch/flywheel.

Hope that helps.

 

Hmm, see weird thing is, I've heard that before, read all about adjusting the clutch, high engagement point and driven another member's car who's stock clutch was that way, etc... Well, mine isn't. It engages practically right off the floor, just the way I like it (not so low that is might not be fully disengaging, but it's right there in the perfect spot). So what's up with my clutch that it's good from the factory? I have an '03 Track. I also like the stiffness of the '03 clutch; I drove an '06 and hated the new softer clutch.

I'd like the benefits of the lightened flywheel, but am almost afraid of changing the clutch and losing the perfect feel mine has...

 

Dangerously lean with a plenum, Popcharger and Nismo exhaust? I doubt that very much. With test pipes, headers and a TD, maybe. I still get a fair amount of soot on the tailpipes indicating a rich mixture; not as much as stock, but stock tune is overly rich.

At any rate, UTEC & tune is more than I want to spend on that; I'm moving to San Diego in a few months and plan on having my ECU reflashed by Technosquare on-site. That's completely asside from deciding between these two mods (3.9 vs. clutch/flywheel)

 

You be surprized. Maybe cause I'm at 6000' altitude but with my mods in sig I was dangerously lean. The UTEC helped richen me up.

 

Ah, well that explains it. Test pipes will lean you out alot and altitude has a BIG impact. I'm at sea level, though.

 

I know the feeling I was worried too but in the end very satisfied. You'll figure it out. I searched and searched before I did mine and the more I searched the more I got scared of so called flywheel or gear chatter. Finally I said fark it since my car needed the clutch anyway. Good luck with your decision.

 

Yeah, I guess I'll be the same. I've read around enough to really know most of what is being discussed here. I guess I was really looking for some epiphany to come with some new info. I hadn't considered.

The diff. in clutch feel kinda worries me... I guess I could always just swap out the flywheel and keep the stock clutch, but that'd prob be a bad call in the long run with 28k on the clutch.

Anyone have firsthand experience with the UR vs. JWT flywheel in terms of drivability, noise, etc.? What about the Nismo flywheel?

 

Stillen Test Pipes
Injen Exhaust (Angled)
Non-Foulers
K&N drop in filter (Freebie)
350Evo 3.9FD & Viscous LSD
Z-Extreme Grounding Kit (Freebie)

(I have spent very little on my current setup of performance parts)

ie. Under $1000 including install,
Keep searching you will find great deals on used parts, thats are in great condition. As a whole I didnt want to spend alot of $$ on NA mods because I am holding off for FI. With my current modifications my dealership has had no problem fixing any of my warranty requests. With the addition of a JWT Clutch and Flywheel & possibly a plenum spacer it would temporarily keep me happy not to mention give me the leeway to add the FI as long as I stayed under 500tq, If I decided to go over that it would be a mistake to purchase that part due to the high cost of install/ and the initial cost of the part new.

On the other hand I have spent a ridiculous amount of $$ on my suspension setup due to the fact I wanted long lasting quality parts that I knew were new since i never wanted to remove them...

My only recommendation would be to do a Cusco RS LSD with the 3.9FD. I wish thats what I'd have done.



Ive drive an 03 in comparison to my 05 and i love the daily driven softness of my clutch however I was used to a Stage 3+ Spec clutch in my MR2 turbo, and the engagement and the chatter were kinda harsh but it pays off when the car hooks up and is fast as hell. Clutch feel it all about getting the feeling out of the clutch you have... I guarantee after 1000 miles on your JWT youll be totally fine.

Stock I ran a 13.9 at 102 I have yet to run this new setup but a similarly modded 06 ran a 13.6 @ 106 with JWT clutch and flywheel.
If you like to race at all, any kind of racing both setups will increase trap speeds and reduce lap times or ETs.

 

Err... ok; this has absolutely nothing to do with what I'm asking about in this thread, but... ok.




Nah, I'm not into drag racing; I live for the twisties. I've got a decent suspension setup. Really, I'm happy with what I've got; I'm just looking for my next mod and trying to decide between gears or flywheel/clutch. I suppose flyweel/clutch would be the smartest choice, since at some point down the road, I may go FI, in which case the 3.9 gears wouldn't be an option, but then again, I may not.

Haven't thought about upgrading the vLSD; guess that would be about the last handling mod I could do, but looking at better get up and go right now...

 

i have the jwt combo and after i got it installed i felt the difference in the clutch pedal but i didnt feel any difference in power.

 

It has alot but I must have deleted a portion of my post!



there was a section in there that talked about just getting both. looking through our market place and going from there.

Also you should not pay attention to everyone else if you want something for a specific reason get it!!! DONT ASK other people to decide for you, make a decision that you can afford or the one that makes you happiest. Both mods make the car better in any aspect. If you plan on doing both DO THEM! If not then whatever.

 

Oh, lol; that would have made more sense.. Yeah, I know about the rest; just looking for info. and opinions that maybe I hadn't considered yet.

Looks like most people are recommending what they are familiar with or have themselves, which makes sense; I'd like to hear more from people with the 3.9 gears. Accelerating 10% quicker in every gear accross the RPM band sounds pretty enticing...

 

I was interested in different gearing myself but after getting bombarded with misinformation I got scared away. I read about expensive labor, conflicts with VDC, you name it. I had trouble getting solid info. I still want it but am going to do way more research.

 

never had it affect VDC, never had a problem since the labor was free... never had any conflict with my 3.9FD

But on a better note I have decided on my clutch, I will end up with an ATS twin disc!

 

not true. a clutch and flywheel will not increase your trap. i have tested this scientifically. if you are buying a light weight clutch and flywheel for gains in the ET your doing it for the wrong reason. i went from a slipping stock clutch to the tilton with similar 60 ft times on similar nights within the same week at the same track and gained 0 in my trap speed. yes 0 mph gain. if you buy a clutch you buy it for its tq holding capabilities and longevity under stress, rev charectaristics (without load), engagement and weight reduction. do not expect to gain anything in the trap or lower your ET. if the most extreme setup out there for the Z gained me 0 the less extreme ones will do the same.




Hammad