Short Gears and R&P 4.23

[goldNSX]

Hi

I'm thinking about the shorties and maybe the final drive 4.23. I've read the FAQ up and down and still haven't decided yet. Does the final drive 4.23 raise the gearbox noise? I have an original 91 gearbox with 60'000 miles on it and can hear the final drive a little bit. I've calculated with a spreadsheet and canceled the CT 4.55 as it would not be overkill for me. I will go for the shorties for sure but I'm still not sure about the 4.23. Is it really worth $1'000 compared to the shorties alone? I don't race my car. Actually I'm a weekend driver. But I want more acceleration between 30 and 80 mph. Can anyone help me decide.

Thanks in advance,
Thomas

 

[MiamieNeSeX]

Depending on your exhaust , I think it will cancel out any gearbox noise.


Armando

 

[NetViper]

Most people rave about it. Ponyboy got it done and was not really impressed.

The reality is the car is only a very little bit faster.

I have been wanting it for a while, but after track driving a few weeks ago, I found the OEM gears to be great. Of course, I was never below 2nd gear and 65mph.

 

[Andrie Hartanto]

I have been wanting it for a while, but after track driving a few weeks ago, I found the OEM gears to be great. Of course, I was never below 2nd gear and 65mph.

Wow,

what track is this? In everyt track I ran with the NSX I had to use 2nd gear. Including a 6 speed with 4.55

 

[ChopsJazz]

I had the short gears and the 4.23 installed a few years back. I like the change a lot. There is no discernable noise in the final drive and the power comes on a little sooner and feels a little torquier (sp?) at cruising speeds. My engine runs at 3500 rpm at 80 mph in fifth ('91 w/ 5 speed) and 3000 rpm at 70 mph.

One thing you will love about the gearbox is the way the engine stays in vtec on the first gear/second gear upshift at redline. :biggrin:

 

[Larry Bastanza]

Thomas,

Based on your requirements you may want to consider only the 4.23. Since you want better acceleration all the way around, and you are on the street. Overall, in the speed range you mention, the short gears will move shift points around and change acceleration, but in the long run, not a huge change, and in fact, the results of shorties alone may just be more shifts.

But the best advice is to drive a car with the setup you are targetting, before you spend a penny. If you drive a car with shorties and a 4.23 you will have a way better feel if you want both or not.


JMO,
Larry

 

[goldNSX]

But the best advice is to drive a car with the setup you are targetting, before you spend a penny. If you drive a car with shorties and a 4.23 you will have a way better feel if you want both or not.


JMO,
Larry

Hi Larry,

There are no shorties with 4.23 final drive in Switzerland as far as I know. Some people are getting the shorties alone. I think I can manage to drive one but I think I can't drive it long enough. My main reason for a change is the big jump from 1st to 2nd. In a traffic jam, it's quite hard to drive slowly (10 mph) as soon as I left the 1st for the 2nd. The other reason is overtaking. Most of the time we have a speed limit of 50 mph. When I start in 2nd reving at 44 mph it takes a long time to reach V-TEC and at 7000 rpm (71 mph) I'm much too fast. The same reason is for accelerating up a hill it's and endless time period until V-TEC kicks in. So I think I won't be happy with the final drive alone. The shorties are definitivly set but I'm still not sure if the final drive helps me a little bit more. I have a traction problem in slow corners with the Eibachs. The inner wheel's losing grip. This wasn't with the OEM setup. But I don't like to change the Eibach since the ride height is perfekt and the Type R is far too hard for a sunday racer like me. And the Type S is too high either.

Thanks for your opinion.

Greetings,
Thomas

 

[ScienceofSpeed]

It is hard for me to recommend only doing one gear set. The JDM short gears gets rid of the lag that the non-Japan market NSX experiences. The 4.23 gives the car the extra pep and pull in cornering and uphills. Since there is a large fixed cost with removing and disassembling the transmission, it seems like a waste to only do one gearset.

There have been many reviews online for these gears that you can likely find.

Personally, I think it is one of the best improvements for the early cars.

best regards,
-- Chris

Hi

I'm thinking about the shorties and maybe the final drive 4.23. I've read the FAQ up and down and still haven't decided yet. Does the final drive 4.23 raise the gearbox noise? I have an original 91 gearbox with 60'000 miles on it and can hear the final drive a little bit. I've calculated with a spreadsheet and canceled the CT 4.55 as it would not be overkill for me. I will go for the shorties for sure but I'm still not sure about the 4.23. Is it really worth $1'000 compared to the shorties alone? I don't race my car. Actually I'm a weekend driver. But I want more acceleration between 30 and 80 mph. Can anyone help me decide.

Thanks in advance,
Thomas

 

[Larry Bastanza]

Hi Thomas,

I mis-interpreted your requirement. I will say, for myself, I agree with Chris, I like the combo. Also Chris's point about the labor is correct and a consideration I was not taking into account.

Regards,
LarryB

Hi Larry,

There are no shorties with 4.23 final drive in Switzerland as far as I know. Some people are getting the shorties alone. I think I can manage to drive one but I think I can't drive it long enough. My main reason for a change is the big jump from 1st to 2nd. In a traffic jam, it's quite hard to drive slowly (10 mph) as soon as I left the 1st for the 2nd. The other reason is overtaking. Most of the time we have a speed limit of 50 mph. When I start in 2nd reving at 44 mph it takes a long time to reach V-TEC and at 7000 rpm (71 mph) I'm much too fast. The same reason is for accelerating up a hill it's and endless time period until V-TEC kicks in. So I think I won't be happy with the final drive alone. The shorties are definitivly set but I'm still not sure if the final drive helps me a little bit more. I have a traction problem in slow corners with the Eibachs. The inner wheel's losing grip. This wasn't with the OEM setup. But I don't like to change the Eibach since the ride height is perfekt and the Type R is far too hard for a sunday racer like me. And the Type S is too high either.

Thanks for your opinion.

Greetings,
Thomas

 

[nsxtasy]

I want more acceleration between 30 and 80 mph. Can anyone help me decide.

The numbers (thanks to Bob Butler) should help:

30-80 mph acceleration on all stock '91: 5.82 seconds
30-80 mph acceleration on otherwise stock '91 with 4.235 R&P: 6.06 seconds
30-80 mph acceleration on otherwise stock '91 with 4.235 R&P and short gears: 5.92 seconds

after track driving a few weeks ago, I found the OEM gears to be great. Of course, I was never below 2nd gear and 65mph.

what track is this? In everyt track I ran with the NSX I had to use 2nd gear. Including a 6 speed with 4.55

NetViper said he was never below 2nd gear - meaning, he was never in first gear.

One thing you will love about the gearbox is the way the engine stays in vtec on the first gear/second gear upshift at redline. :biggrin:

The engine isn't in VTEC after the 1-->2 upshift. Revs drop to 5085 RPM with the short gears, so you still have a ways to go before you hit the VTEC crossover point at 5800 RPM. However...

When I start in 2nd reving at 44 mph it takes a long time to reach V-TEC and at 7000 rpm (71 mph) I'm much too fast. The same reason is for accelerating up a hill it's and endless time period until V-TEC kicks in.

...this is not correct, and is a very common misconception (one which I myself made when I wrote some text that is included in the FAQ). The rate of acceleration does not increase above the VTEC crossover point (although the louder drivetrain noise sometimes make it seem that way). The advantage of VTEC is that it keeps acceleration from decreasing as revs rise. Acceleration within any gear is a function of torque at the wheels, which is engine torque less drivetrain losses. You can see from the graph below that there is no significant increase in engine torque above 5800 RPM.

On the other hand, the large gap between first and second gears does indeed cause a significant reduction in the rate of acceleration. However, this is because of the relatively large difference between the gear ratios, not because of where you are in the RPM band. (And the short gears do help with this, although, as with most gearing changes, what you gain there, you lose elsewhere, namely in the speed bands where the shorter gears force you into a higher gear, and in the wider gaps of the 3-->4 and 4-->5 upshifts).

The biggest difference in gearing changes will come in the feel of the car, rather than actual acceleration improvements. You will reach redline faster, but at a lower road speed. This is perceived as faster acceleration, to a much greater extent than it actually is. You may like it; you may not. Larry's advice to try the setup you're considering is great advice...

 

[Andrie Hartanto]

NetViper said he was never below 2nd gear - meaning, he was never in first gear.

Thanks for the clarification, I misread it.

I was having goose bump for a second thinking there might be a track that fast in the east coast. Would have made some plan to go

Just out of curiosity, are all the circuits in the east coast, fairly high speed? Like Watkins Glen for instance?

 

[docjohn]

Just out of curiosity, are all the circuits in the east coast, fairly high speed? Like Watkins Glen for instance?[/QUOTE]
I'm not sure what your frame of reference is for a slow-fast track.What tracks out your way would you consider slow and fast.Is your criterior max speed atainable or an average speed for the whole circuit?Compared to the glen lime rock imo is percieved to be slower,becuse it is shorter,with a single shorter straight,and you are always transitioning to turn everywhere else.There is a configuration at Pocono called the east course which is technical due to many turns so it is "slower".Sorry to hijack this thread.Andrie you want to start another thread in racing forum about tracks?Might be my only hpde fun over the winter :frown:

 

[nsxtasy]

Just out of curiosity, are all the circuits in the east coast, fairly high speed? Like Watkins Glen for instance?

No, not at all. The West Coast has some tracks where you spend a fair amount of time on long straights that make them relatively high speed, such as Laguna Seca, and there are others where there are tighter turns with less space in between them, such as Spring Mountain in Pahrump. The same is true of the East Coast, with Watkins Glen as a faster track and the late, lamented Bridgehampton as a slower track. The Midwest, too, has fast tracks (Road America) and slower tracks (GingerMan, Putnam Park).

While this sounds like a tangent, it's not, necessarily. Any particular track may tend to be better or worse for a particular gearset. For example, take a track like GingerMan. You spend a lot of time there between 65 and 90 mph. With a stock '91 NSX, you upshift and downshift five times around the 1.8-mile track, between second and third gear, to take advantage of second gear where it's available. With an NSX with 4.55 R&P and short gears, you wouldn't use second gear at all.

 

[goldNSX]

The numbers (thanks to Bob Butler) should help:

30-80 mph acceleration on all stock '91: 5.82 seconds
30-80 mph acceleration on otherwise stock '91 with 4.235 R&P: 6.06 seconds
30-80 mph acceleration on otherwise stock '91 with 4.235 R&P and short gears: 5.92 seconds

The stock gearing doesn't have to shift up to 3th in this range, that's true. I hardly ever accelerate from 30 to 80, most of the time it's 31 to 56 (or 63) or 50 to 87 mph. I was never on the German Autobahn (shame on me, I know )

The engine isn't in VTEC after the 1-->2 upshift. Revs drop to 5085 RPM with the short gears, so you still have a ways to go before you hit the VTEC crossover point at 5800 RPM. However...

Yes, thats' true.

...this is not correct, and is a very common misconception (one which I myself made when I wrote some text that is included in the FAQ). The rate of acceleration does not increase above the VTEC crossover point (although the louder drivetrain noise sometimes make it seem that way). The advantage of VTEC is that it keeps acceleration from decreasing as revs rise. Acceleration within any gear is a function of torque at the wheels, which is engine torque less drivetrain losses. You can see from the graph below that there is no significant increase in engine torque above 5800 RPM.

I always believed that you need power to accelerate which means torque AND rpm. You can't have one without the other if you like to accelerate. High rpms doesn't help you very much if there is no torque that's true. The superiority of the NSX engine is that I can find torque everywhere. Even if the torque of the engine was linear flat all over the rpm-band, the short-gears will give me higher rpms and therefore more power. Correct me I've I wrong. If I take the 4.23 into account I think that it doesn't help me at low speed (below 35 mph) as the rpm-difference is very small. The 4.23 will help me at 5000 rpm and more I think.
I clearly see a difference between the graphs and my driving perception. I can hear AND feel the V-TEC kicking in. It's not very hard (as my former Integra Type-R) but still recognizable. At 6000 rpm the power is one (small) step higher and seems to be very linear to me without any peaks.

The biggest difference in gearing changes will come in the feel of the car, rather than actual acceleration improvements. You will reach redline faster, but at a lower road speed. This is perceived as faster acceleration, to a much greater extent than it actually is. You may like it; you may not. Larry's advice to try the setup you're considering is great advice...

It would be interesting to drive a short gear setup with and without the 4.23 R&P. And I think I have to through all of them in so we have at last one NSX in Switzerland people can compare between.

Thank you very much for your thoughts, nsxtasy.

Greetings,
Thomas

 

[LJSB]

I have the short gears and 4.23 in my 1996.
There is no gear box noise from the 4.23 and I believe it is because it is a OEM part.
I really notice the difference now when I drive a stock 5 speed and seemingly the stock gears are so tall and long compared to mine.
The car just feels like it has more snap and pep with the shorties and 4.23 and to me should have come this way from the factory.
Is it worth the extra money? Yes, just like the car itself it is worth the extra money for what it delivers.
The change just makes the car more enjoyable and fun because it brings out the best of the car, the VTEC engine band.
I would do it again and now don't think I would want to own a 5-speed without it.
The change is like a woman in a tight dress and heels. The outfit doesn't really change the girl it just gives a accent, a perception that makes her seem hotter and more exciting. Really she's still the same great girl or in this case, car, just higher revving. :wink:

 

[docjohn]

Joe,,,,,you need a vacation

 

[LJSB]

OK. Sounds good to me. :smile:
If all these folks can call the car their "baby", can't I liken it to a beautiful woman? :wink:

I'm coming up on 1,000 posts!

 

[nsxtasy]

Even if the torque of the engine was linear flat all over the rpm-band, the short-gears will give me higher rpms and therefore more power. Correct me I've I wrong.

You're right... and you're wrong.

Power (horsepower) is proportional to torque times revs. The higher the revs, with torque relatively constant (as it is for most of the NSX revband), the higher the horsepower.

However, ACCELERATION is a function of torque. If the torque stays the same, then the rate of acceleration stays the same.

So you're correct that the number of horsepower increases as revs rise, but you're incorrect if you think that makes the car accelerate at a faster rate.

You can read more about torque vs horsepower and how they (and gearing) affect acceleration in this article.

If I take the 4.23 into account I think that it doesn't help me at low speed (below 35 mph) as the rpm-difference is very small. The 4.23 will help me at 5000 rpm and more I think.

The 4.235 R&P will make the car accelerate faster at any engine speed. (That's basically just saying that the car will accelerate faster in a lower gear than in a higher one. The lower the gearing with the same engine speed and thus the same engine torque, the faster the acceleration.)

However, that does not mean that the 4.235 R&P will make the car accelerate faster at any road speed. It may, or it may not. (Basically, the car accelerates faster with the 4.235 at those speeds for which it is in the same gear with either R&P, and slower with the 4.235 at those speeds for which it must upshift to a higher gear so as not to exceed redline.)

I clearly see a difference between the graphs and my driving perception. I can hear AND feel the V-TEC kicking in. It's not very hard (as my former Integra Type-R) but still recognizable. At 6000 rpm the power is one (small) step higher and seems to be very linear to me without any peaks.

It just doesn't happen that way - not on a stock NSX. If there were a significant increase in the rate of acceleration, there would have to be a huge jump in torque on the dyno chart. There isn't. If you aren't convinced, have your car dynoed and see if the engine jumps 25 horsepower when you hit the VTEC crossover point. It won't.

 

[goldNSX]

The change is like a woman in a tight dress and heels. The outfit doesn't really change the girl it just gives a accent, a perception that makes her seem hotter and more exciting. Really she's still the same great girl or in this case, car, just higher revving. :wink:

Hi pbassjo!

Very good comparison! I think we have to put it up in the FAQ. That's what I always thought of my NSX. The long gears seem to me like the missing heels. :wink:
To be serious: I have a final question about traction: In FAQ is stated that with shorties and 4.55, you can loose track on the rear wheels while upshifting from 1st to 2nd. What about the shorties and 4.23? Other scenario: When I floor the throttle in 2nd at 2000 rpms in slow corners, TCS is lighting (?sp). I think the Eibach/Bilstein are too soft for good traction with the shorties. The OEM setup was better concerning traction only. Does anyone have similar experience?

Thank you very much for your help!

Greetings,
Thomas

 

[goldNSX]

If all these folks can call the car their "baby", can't I liken it to a beautiful woman? :wink:

Well said! My grilfriends left me because they thought I treat my NSX better than them mostly due to waxing them (my cars! ) with my bare hands. The combination of girls and cars is certainly much better.

 

[burbel]

I've had the shorties and 4.235 in m NSX now for about a year, and have been very happy with them. My mom's NSX has the stock gearbox, and while I was replacing my supercharger belt, I got the drive that NSX for a week, and remember what it was like, back to back.

If you are like me and the fastest you accelerate to is 60-65mph tops, then the short gears are for you. If you're like my friend that likes to go up to 85mph+ on the same stretch of road, then stick with stock, IMO. You want the gearing that fits the way you drive.

As for breaking the traction loose, I have never broken the tires loose with the 1-2 shift with my gearing setup and the Comptech supercharger; I don't think this would be something to worry about. Perhaps the person that mentioned looss of traction was power-shifting?

 

[LJSB]

The OEM setup was better concerning traction only. Does anyone have similar experience?

Nope.
I think this mod should be good for your exit speed when you come out of a corner but I'm not a track guy. Docjohn is and though I think he's running short/4:55, he would have a better sense of how this type of mod performs on the track and street.
doc?

 

[nsxtasy]

Traction depends a lot more on driver technique and the model of the tires (and, for TCS, the size of the tires). For example, if you're using inexpensive, high-mileage tires that are not particularly sticky, it's easy to lose traction and activate the TCS.

 

[goldNSX]

Traction depends a lot more on driver technique and the model of the tires (and, for TCS, the size of the tires). For example, if you're using inexpensive, high-mileage tires that are not particularly sticky, it's easy to lose traction and activate the TCS.

Normally I'm driving the S-03 and had the effect described above with losing track in slow corners. I tried a Michelin Sport in the rear with all equal the same and didn't have so much problems. The michelins have a softer sidewall but harder rubber which seems to last much longer. My tire size is 265/35/18 and 215/40/17 in the front. The relation from rear to front is 1.064 which is not far away from stock. Can I do better with 275/35/18 or is my question just theory. :wink:

Greetings,
Thomas

 

[nsxtasy]

S-03
.
.
.
My tire size is 265/35/18 and 215/40/17

Those tires should work fine with the TCS.

Maybe you're just a little bit too... enthusiastic, going around those corners?