Thanks for addressing my question, though I disagree principally with your suggestion of comparing TQ to RPM. While it would show a 15% (if going the 4.08 route) gain in torque at every point, it wouldn't really show how that translates into actual performance on the road or in a straight line race. (Not that straight line racing is all I'm concerned with - I just wanted to completely understand the pros and cons of this mod over what I currently have) And illustrating it in terms of TQ/Force v. Vehicle Speed is one of the best ways of doing that. 4.08 gear v. OEM gear doesn't take into account that that the gear itself is 15% shorter and you'll be shifting earlier into a gear with substantially less torque.

But I think we're on the same page. As it is, I've already increased the rev limiter via an Uprev tune (I'm sitting at 7250 right now, so another increase isn't going to happen). Still, though, the fact that there is so much usable torque in daily driving situations... I'm really leaning toward getting it. Thanks again for answering my questions.

 

You're conclusions are pretty spot on in your previous post. At any speed above about 40mph, theres a kind of a switch being played by both cars, where one is at an advantage, then the other. 1 car needs 2 gears to cover the speed window, while the other only needs 1. Below ~40mph, the shorter gear wins, why?, because the other car doesn't have anything lower.

Selecting the gear for the drag strip, or a race track is different than selecting one for your discussion. If you want better acceleration than the stock gear, under ALL circumstances, you want to match your rev limit and powerband to the shortest gear possible, that allows you to retain IDENTICAL top speeds per individual gear.

TK

 

With the 4.08s that is practically impossible without a built motor that is capable of making good power at higher than OEM RPMs.

 

Right. It was directed at the various OEM engine configurations with different rev limits, i.e. 6600 nonrevup, 7000 revup, 7500 HR.

Raising the RPM on an engine whose volumetric efficiency is rapidly declining, for the sake of using a shorter gear would be a bit moot, except under specific circumstances.

 

I know topic has been beaten to death and I've read this post 3 times, but i had to ask.

I've regeared all my motorcycles and couldn't be happier. But on my 08 HR i could the somewhat tall 'overdrive' 6th gear. I want to regear to 4.083 for better acceleration, but wonder if that wouldn't be the same as staying in a lower gear all the time..with the exception of 1st gear of course. thoughts?

 

Well, as I unfortunately discovered, despite the 15% increase in torque to every gear, the length of every gear is shortened by 15%, and that happens to negate the gains you get from the gears beyond 1st. So I have to be honest and go against the grain on this by saying that unless you'll maintain traction in 1st gear, it's a lot of money for something that *feels* quicker but really isn't.

Each gear is going to be much more powerful, but much shorter. And so the math dictates and the simulations show that beyond 1st gear, it's not going to yield any gains in comparisons that include acceleration through more than one gear.

[Also, if you ever want to test it out and have the means, you can always pop in Forza Motorsport or Gran Turismo and make the modifications there.]

 

If you take the time to understand the gears and their purpose in totality (the first post giving you the bulk of this info), you'll see that especially for the DE's (2003-2006), increasing the rev limiter is the other half to the equation to making the gearswap shine. No mod is zero sum - they are, instead, complimentary. If you aren't willing to do the basics to let one mod maximimze it's utility, you're best route is simply leaving the car stock

 

I'll take this opportunity to once again state that the first page does not provide the real world practical implications in terms of straight line, multiple-gear, acceleration. It is far from obvious that there are no actual gains over stock beyond 1st gear, and it requires a more extensive understanding of what is going on. The synergy of the information is what yields this understanding, and that is absent in the first page.

On the increasing the rev-limit point, I'd love to see a comparison of the gains over stock in gears 2-6 between a Z with new gears and Z without them. I have a feeling that the performance gains yielded over the previous configuration in both cases will be virtually the same.

 

onagao, thank you for being so analytical. I know alot of folks just throw 'mods' on just because it's available.

I understand your concern about loosing the 'synergy' affect when 'all gears' are combined to equal 'total' acceleration.

I myself was pretty happy with the current factory gearing. Acceleration is pretty good, 6th acceleration is adequate while providing somewhat good MPG and low rpm/noise, etc...Until someone tried to pull on me on the freeway. Normally, I just ignore them, being a motorcyclist if I wanted to go FAST, I just hope on my bike. But I figure this would be a good opportunity to play with the gears.

While the stock gearing provides good acceleration, under 'spirited' driving...it takes 'too long' in any gear for it to go through the powerband. Under these circumstances, I believe a shorter gearing (4.083?) would let the engine reach its sweet spot much faster and accelerate that much faster.

 

is this confirmed? id hate to buy a diff from one of these trucks and come to find out they wont fit. as far as what others are saying, yes, they will fit off of a frontier. im just close to buying a new set but if i could save some money by buying a used pumpkin, that would be cherry!

 

Here's a screen capture from the 05 Frontier FSM, RFD-35

QR25DE M/T has the 4.083 gear ratio

 

sweet thanks! but i bought ring and pinion from mynismo already

 

just my quick review on these:

over this side of the pond most of the tracks dont have long enough straights to warrant the gearing in the standard zed, so after speaking with adam@z1 for a while i decided to go down the 4.08 route,

car pulls out of corners much better than it did and ive found i can short shift in a couple of places on a few tracks and still pull out of the apex and be on the power as it were, there is obviously a bit more grunt there but for me its made the car a bit more flexible in terms of being able to put the power down when needed, i can see why this would be good for drag racing but i guess more shifts would reduce time a little?

 

been reading up on this and just skimmed through all 33 pages. looking for some reviews from 5at de owners with some miles under their belt using 4.083 gears. anyone care to chime in? I've seen multiple folks suggest that 5at owners stick with a 3.7, and that the 4.083 might strain 5th gear too much, but really no concrete info :|

 

I would highly doubt many auto owners have these, or any other gears in the car, because it also necessitates changing the differential

 

ah. I have a local pal driving an mt with these gears already in and he wants my 3.3. just trying to figure it all out and if I'd be happy with this change as a daily driver, don't want to incur too much cost on the swap.

 

you would just need to totally swap pumpkins, then it would work fine

I forget who on the boards had an auto with the 4.08 - it was someone in maybe AZ, I just can't remember the screen name

 

cool deal. thanks Adam, helpful as always.

 

anytime

 

how would a 4.083 swap do on a g37s 6mt? im going to be buying one soon and i think this is the first mod i would want to do, afterwards i/h/hf cats and a tune.

i dont care about top speed i rarely go over 120mph. and i can buy the same gears for sale as the 350/g35 correct?