Honda JDM Short Gearset

[SINCITY_NSX]

I’m looking in to buying the 4.23 short gear set for my 91 . I’m looking for some input on the upgrade any input helpful. I wont be racing the car vary often it will be more of a every day driver.

 

[Viper Driver]

In my opinion, it's the way the U.S. NSX transmission should have come from the factory. Don't forget about doing either a 4.23 or 4.55 ring & pinion at the same time, and you'll have a car that is MUCH more enjoyable to drive!

 

[NoClgDeg]

I think you should look into getting the six speed trans.

 

[ChopsJazz]

I have done this to my '91 (short gears and 4.23 R&P) and I'm very happy with the results. The car just feels as if it has more pep.

 

[nsxtasy]

I’m looking in to buying the 4.23 short gear set for my 91

There are a lot of previous topics about this.

You may want to describe them differently, because these are two different gearing modifications, and you're making it sound like it's all one thing. The short gear set, for the '91-96 five-speed, is a different (shorter) set of gears - second, third, and fourth gear - that reduces the space between first and second, and increases the space between third and fourth, and fourth and fifth. It has no effect on the relationship between engine speed and road speed in first gear or fifth gear, although it changes the relationship between those and the adjacent gears.

The ring and pinion (R&P) gear is a gear that all drive gears use. 4.23 (actually, 4.235) is the numeric ratio of this gear, as compared with the stock ring and pinion gear and its 4.062 ratio. Using the shorter (the higher the number, the shorter) ring and pinion gear affects the relationship between engine speed and road speed in all gears.

These are the calculated 0-60 and 1/4 mile times, in seconds:

5.31 13.67 Stock
5.09 13.56 Short gears
5.18 13.57 4.23 R&P
4.96 13.48 Short gears and 4.23 R&P

If your car is in the snap ring range and hasn't had this addressed, then I would recommend replacing the snap ring and upper transmission cover at the same time as you replace the gears, so the snap ring problem is no longer an issue for you. Also, have your hub selectors and synchros examined for wear, and replaced if needed. As long as you're going to pay for two days of labor to open up the transmission, you may as well take advantage of it if any other tranny work is needed. And if you're close to your next 30K/60K/90K service, remember that your transmission fluid is changed as part of this process, so you won't need to do so again as part of that service.

 

[CRX B16B VTEC]

I donno if this is what you are looking for, but it is on sale on Yahoo auctions Japan at the mo... (almost finished without a bid)

Currently at 258000 Yen

NSX-R gearbox 5 Speed (I guess it is the old Type R) with ATS 1.5 way LSD.

http://page2.auctions.yahoo.co.jp/jp/auction/b40581192

 

[kenjiMR]

I donno if this is what you are looking for, but it is on sale on Yahoo auctions Japan at the mo... (almost finished without a bid)

Currently at 258000 Yen

NSX-R gearbox 5 Speed (I guess it is the old Type R) with ATS 1.5 way LSD.

http://page2.auctions.yahoo.co.jp/jp/auction/b40581192

Maomaonsx on this board is selling this brand new for pretty cheap. You should contact him.

 

[sjs]

I would second the idea of considering a jump to the six speed if within your budget. In terms of pure performance I don't think either are good bang for the buck, but in terms of pure enjoyment both seem to be a popular mod. As already noted, this is a much discussed topic. Searching the forum will return more opinions than you’ll want to read.

I believe that Dali and/or Basch Acura offer various options ready to bolt in, which saves you time and probably reduces your risk unless you have an experienced tech.

 

[nsxtasy]

I would second the idea of considering a jump to the six speed if within your budget.

Changing to a six-speed (IOW, with the same weight and power as a '91-94 NSX Coupe) means that 0-60 and 1/4 mile times are 5.09 and 13.56 seconds, respectively.

You can also install the 4.235 or 4.55 R&P with the six-speed. (The 4.235 is a recent Science of Speed introduction.)

Like sjs, I think there are other mods that give you more bang for the buck, such as header/exhaust and/or supercharger. Especially if you're not already having other transmission work done anyway.

 

[brickdds]

I have driven my 94 with the stock setup for a little over 2 years and with the 4.23/short/lite-flywheel/centerforce clutch setup for about 6 weeks now. What's the difference? Well the numbers don't do justice to the overall impact made here. Breaking it down in my own experience, I will describe it in subjective terms:
4.23: This is simply a must have once you open the tranny case; it simply zips through the gears and down the road with more zeal giving the car a 'lighter' feel overall. BTW it is a Honda part as opposed to the 4.55 comptech which has a history of problems (based on reports by owners of this R&P)
"short gears" basically this serves one benefit: that being the elimination of the sizable drop in rpms on shifting into second; the short gears puts you higher in the rpms and consequently gives you access to more horsepower and thus more acceleration down in 2nd gear. There really are no significant advantages beyond that (IMO)
What you did not mention and should consider is the lightened flywheel and believe me, every little bit helps!
BTW, shortly after buying the car I got the RM intake and exhaust and can say unequivocally the tranny upgrades aforementioned made a night/day difference in PERFORMANCE, while the intake/exhaust upgrade was negligible in this regard. That said, I would agree that bang for buck return is pretty high here given the fact that with the intake you can actually HEAR the engine and with the exhaust it adds both an agressive note and appearance to the car. Well worth it for both I&E. The header offers neither. Maybe I am missing something here but I don't believe the figures speak too well for them in terms of bang for the buck either. But if you go the FI route then it seems like a no brainer.
Hope this helps.

 

[SINCITY_NSX]

Thanks for all the input on this. I already have RM intake, Exhaust and Taitec GT headers. I might buy the 6spd don’t know just yet but if I don’t I was checking to see what the input was on this setup.

 

[whiteNSXs]

I think you should look into getting the six speed trans.

NO WAY! When the tranny in my 1992 broke due to snap-ring, I did extensive inquiries about the 6 speed tranny conversion. The total was so expensive that one might just buy the 1997+ car, if one is so inclined to have the 6 speed, which is what I did. The actual 6 speed tranny gives your the short gears and that's it.
Steve

 

[TigerNSX]

I did read a lot of posts on this topic. However, I am a bit confused again. Is okay to get just the 4.23:1 R&P on stock 91-96 5 speed gears without changing them to short gears?

 

[Ponyboy]

However, I am a bit confused again. Is okay to get just the 4.23:1 R&P on stock 91-96 5 speed gears without changing them to short gears?

Sure, it's ok. Check the the FAQ or the SoS web site. They'll show you a comparision of the numbers with and w/o.

On another note, I hear that CompTech isn't offering the 4.55 anymore b/c of lack of interest/low or no sales. If you have a 4.55 you may have a hot commodity.

 

[brickdds]

. Is okay to get just the 4.23:1 R&P on stock 91-96 5 speed gears without changing them to short gears?

Why on earth would you KEEP the stock gearset once you have the tranny case cracked open and the labor paid for?

 

[nsxtasy]

"short gears" basically this serves one benefit: that being the elimination of the sizable drop in rpms on shifting into second; the short gears puts you higher in the rpms and consequently gives you access to more horsepower and thus more acceleration down in 2nd gear.

This is not an accurate description of how the short gears help you.

Remember, acceleration is a function of torque at the wheels, which is torque at the crank times gearing (less drivetrain losses). As you can see from this graph:

torque at the crank is virtually constant from 4000 RPM to 7000 RPM, and this range includes the lowest RPM where either gearset places you after the upshift. The rate of acceleration is constant from 4000 RPM to 7000 RPM and beyond (although it does get louder as revs rise). Being higher in the RPMs after the upshift does not give you more acceleration.

The reason that the shorter gears give you better acceleration is because of gearing, not because of the point in the RPM band where you wind up after upshifting (although that point is a reflection of the difference in gearing). Go back to the statement above, "Remember, acceleration is a function of torque at the wheels, which is torque at the crank times gearing (less drivetrain losses)." This statement should make it clear exactly why acceleration is better with the shorter gears - because the gears are shorter, and this gives you a gearing advantage - not because of any greater torque coming from the engine at one point in the revband over another.

If you would like a more lengthy explanation, including how horsepower numbers reflect this, read this excellent article about the difference between torque and horsepower, and how gearing comes into play.

Why on earth would you KEEP the stock gearset once you have the tranny case cracked open and the labor paid for?

I just had his tranny case opened last month, and I did not replace my stock gears with short gears. Looked at on an overall basis, the short gears basically help acceleration at road speeds between the upshift to second and the upshift from second to third - roughly 40 to 70 mph - and hurt acceleration at higher speeds. Because I spend most of my time on a racetrack at speeds over 70 mph, I did not want this mod. On many tracks, the stock five-speed gearing has an advantage over cars with shorter gearing, because of the ability to keep the car in second gear powering out of turns.

 

[ak]

OS giken has 4.4 final as well if you want something between NSXR and 4.55 final, though Dali is the only one who carrys them in US(I think) and Mark told me he only has 2.

I also remember Chris at SOS mentioning something about their own 4.4 final, if he can comment on it.

 

[MiamieNeSeX]

I dont know about graphs and actual times, but as far as the feel of the car after the following mods it is incredible, almost like driving a different car. I just finished doing the clutch, lightweight flyweel, headers and high flow cats along with short gears and the 4.23 ring and pinion. It feels much much faster and pulls hard all the way thru all the gears. Another thing that moves faster is the fuel gauge but such is the price we pay to live in the fast lane............... good luck with your decesion, and if you can drive one with the short gears and ring and pinion, I beleive you wouldnt hesitate to get it.

 

[brickdds]

I just had his tranny case opened last month, and I did not replace my stock gears with short gears. Looked at on an overall basis, the short gears basically help acceleration at road speeds between the upshift to second and the upshift from second to third - roughly 40 to 70 mph - and hurt acceleration at higher speeds. Because I spend most of my time on a racetrack at speeds over 70 mph, I did not want this mod. On many tracks, the stock five-speed gearing has an advantage over cars with shorter gearing, because of the ability to keep the car in second gear powering out of turns.

TigerNSX are you channeling thru NSXTASY?
If so that's pretty remarkable, but maybe you can answer using your own moniker since this is confusing me.

MiamieNSX I think you are right on the mark.

 

[TigerNSX]

TigerNSX are you channeling thru NSXTASY?
If so that's pretty remarkable, but maybe you can answer using your own moniker since this is confusing me.

I am sorry.. what do you mean???

 

[brickdds]

First this:

[KS] The point of close-ratio gears is to keep the engine at the highest possible RPM and therefore HP. The stock gears are not optimal because there's a gap between 1 and 2 that makes the revs drop from 8000 to 4499, which is lower in power than the "short" gears, which make revs drop from 8000 to 5085. So far, so good (and this is why there's greater acceleration in that 40-60 mph band with the short gears).


Now this:

The reason that the shorter gears give you better acceleration is because of gearing, not because of the point in the RPM band where you wind up after upshifting

Hmmm.....
Maybe you would like to elaborate on the inconsistencies in your posts or modify the entry in the FAQ. I am just a little confused.

 

[TigerNSX]

uh... I never wrote those... I really don't understand what you are talking about...

All I said in this post is "I did read a lot of posts on this topic. However, I am a bit confused again. Is okay to get just the 4.23:1 R&P on stock 91-96 5 speed gears without changing them to short gears?"

 

[nsxtasy]

The FAQ is, basically, wrong.

Does that help?

 

[nsxtasy]

I dont know about graphs and actual times, but as far as the feel of the car after the following mods it is incredible, almost like driving a different car.

Here's why.

With the stock gears, it takes 6.59 seconds to go from 0 to 70 mph and 7.98 seconds to go from 0 to 80 mph.

With the short gears and the 4.235 R&P, it takes 6.12 seconds to go from 0 to 70 mph and 7.98 seconds to go from 0 to 80 mph. Yes, acceleration from 0 to 80 mph is exactly the same with the short gears and the 4.235 R&P as it is with the stock gears and R&P.

However, the shift points are lowered with the short/4.235 combination; the upshift to third gear takes place at 70 mph instead of 80 mph. If you look at the numbers above, compare the time it takes to go from a stop, until you start upshifting to third gear. With the stock gears, this takes 7.98 seconds. With the short/4.235 combo, this takes 6.12 seconds. That is a difference of almost two full seconds in the time it takes you to reach redline in second gear (even though it takes you exactly the same amount of time to reach 80 mph). THIS is what you are feeling - the shorter time it takes you until you upshift, which is much much shorter than the difference in the time it takes you to reach a given road speed. In other words, most of what you are perceiving is due to the lowering of the shift points, rather than the difference in the actual rate of acceleration.

Hope that makes sense.

 

[brickdds]

TigerNSX: although explanations of jokes eliminate any humor in it, I will explain anyway.
The question was asked to you, but NSXTASY took the liberty of answering it; although it was not posed to him. Channelling is the paranormal term referring to the claimed ability to assume another persons existence in essence allowing one person to live through another.

The FAQ is, basically, wrong.

Just curious then; who is "KS" as referenced by the entry in the FAQ.

And why is erroneous information being allowed to stand as gospel without being corrected/eliminated?