Short Gear Review

[Honcho]

Tim, Ken's main point in all of his short gear critiques is that there are certain speed ranges where the short gears do not accelerate as fast as the USDM gears. Most of these ranges are near or above 100 mph. Here they are (using my current rear tire diameter of 24.9 inches):

75-85 mph --> If you step on the gas anywhere in this range, you will be in 3rd gear with the short gears and 2nd with the USDM. 2nd accelerates faster than 3rd.

104-119 mph --> If you step on the gas anywhere in this range, you will be in 4th gear with the short gears and 3rd with the USDM. 3rd accelerates faster than 4th.

141-151 mph --> If you step on the gas anywhere in this range, you will be in 5th gear with the short gears and 4th with the USDM. 4th accelerates faster than 5th.

I find this is a small price to pay for VASTLY improved "street", i.e. day-to-day, driving. Having just spent an entire day within the first of the above-listed ranges, I find the statistical "disadvantage" to be nearly imperceptible. My NSX is now fun to drive on the street AND the track.

I'm sorry if I"ve read you wrongly Ken but it seems to me that you have never given any examples of "street" use where you didn't mention "street light to street light" type examples. You'll have to show me where I'm wrong on that. You usually are very specific about any reference to short gears advantages.

Now - I don't know where you live - but where there are twistie type roads - which is what our cars are designed for - then that's also "street use". That's the kind of street use that most folks long to find - that's the kind of roads that Atlanta has in many parts - CA too - as in canyon carving. If your in Florida - or many cities in the USA have a grid system - that's more like the "street light to street light" benefit I blieve you describe. I've never heard you be a proponent of using the short gears on twisty type roads. It seems as has been discussed by many here in this thread that below 100 on twisty roads you get a definite advantage over the long gears.

Are you now saying that's the case or not? Sorry to be putting you on the spot but I'd love to hear your answer to this one. Maybe I have you all wrong?

 

[nsxtasy]

Tim, Ken's main point in all of his short gear critiques is that there are certain speed ranges where the short gears do not accelerate as fast as the USDM gears.

Also that, overall, the stock gears accelerate faster above 70 mph, and that most track driving takes place above 70 mph, and that the stock gears are better suited (i.e. are faster) on most racetracks for that reason.

 

[tbromley]

Wow, did I hit a nerve Ken? - I mean those are mighty strong words here - "attacking" - I find it very difficult to understand the use of that term in my rather benign post or reply to your post? I'm sorry if I've offended you - but you are now reading me all wrong.

You know you bomb SFNSXguy all the time and you two seem to have an endless discourse on this topic and always you tend to be very specific on what you're discussing. You post all the specifics on different R&Ps and short gears vs. long and all this track stuff which I'm sure you are waaaay more qualified to talk about than I am. But to call my post an attack on you is pretty silly. I mean you obviously can dish it out....it's the small questions like mine that get you all flustered - I'm not sure I understand. I guess you just didn't want to repeat yourself or something. I believe I asked a very pointed question a simple reply would have been sufficient.

You see I regard you as somewhat of an expert on many of the topics that are discussed here. I didn't think that by merely asking a simple question that would be interpretted so far away from what I meant.

You are saying in this post no matter what kind of driving one is doing that the short gears are better below 70 mph. I can accept that. No problem. Glad you clarified that - which means in the twisties below 70 mph which is what one is most likely doing on any mountain roads, similar in many ways to the tight turns on tracks that the short gears are better. I'm glad to hear that from you. Thank you.

Sorry to get you all excited - I surely didn't mean to do that - and I'm sorry if you thought my point was to "attack you"; very sorry indeed - I surely did NOT mean it like that. I was merely trying to make sure I understood you.

You certainly have. You continually pick apart my posts, trying to claim I never said stuff I've said, claiming I said stuff I never said, etc. And it's not just me; you seem to do this a lot here, with other people's posts, too. NSXprime should be a place where we share expertise and opinions, but it should be focused on knowledge, not on what words we use to communicate that knowledge, and especially not on spending all your focus on picking apart other people's posts, or on arguing on and on and on and on, endlessly.


So now you're attacking me because I use one example and not another example. This is exactly the kind of hostile attack that I'm talking about. You like to argue and attack others for not saying exactly what YOU want others to say. Why don't you just concentrate on saying what YOU want to say, and let others use their own words to say things, without you continually and endlessly attacking them for doing so? Why do you have to turn every topic you post in into an endless, petty debate over semantics?

I've stated very clearly that the short gears are faster between 40 and 70 mph. I don't need to add every possible situation in which someone might be driving below 70 mph. People can figure that part out for themselves.

 

[tbromley]

Thanks for your reply Honcho - I understand what you are saying. It's all about torque developed in the lower gears- I get that.

Glad you like your short gears - they surely sound like something many of us that don't track or do very little of would like to do. I've heard this endless times from other Primers that have done this. Obviously for most there is surely a good reason to consider it. That and to consider keeping the OEM R&P. Thanks again...

 

[nsxtasy]

You know you bomb SFNSXguy all the time

I don't "bomb" him, meaning I don't post personal insults about him (even though he's frequently done that to me). I simply stated my opinion, which is different from his.

But to call my post an attack on you is pretty silly.

Okay, fair enough. It just seems like you're picking apart my WORDS (rather than the concepts, facts, or opinions underlying them) by claiming I never said things I did say, and trying to get me to say certain things.

You are saying in this post no matter what kind of driving one is doing that the short gears are better below 70 mph.

Well, there are all kinds of "better", and not all follow. For example, if you're looking for maximum acceleration, the short gears don't make any difference below 45 mph. (Shorter R&P is a different matter.) So for "around town" driving below 45 mph, you'll have the same acceleration available to you with the stock gears or the short gears. But around town, you're probably not looking for maximum acceleration anyway. (How many of us stay in first gear all the way up to 45?)

If you're talking strictly in terms of maximum acceleration, the short gears don't make any difference below 45 mph, and have an advantage from 45 to 73, then are at a disadvantage above that.

 

[tbromley]

Thanks Ken, no dis intended...I appreciate your perspective.

I don't "bomb" him, meaning I don't post personal insults about him (even though he's frequently done that to me). I simply stated my opinion, which is different from his.


Okay, fair enough. It just seems like you're picking apart my WORDS (rather than the concepts, facts, or opinions underlying them) by claiming I never said things I did say, and trying to get me to say certain things.


Well, there are all kinds of "better", and not all follow. For example, if you're looking for maximum acceleration, the short gears don't make any difference below 45 mph. (Shorter R&P is a different matter.) So for "around town" driving below 45 mph, you'll have the same acceleration available to you with the stock gears or the short gears. But around town, you're probably not looking for maximum acceleration anyway. (How many of us stay in first gear all the way up to 45?)

If you're talking strictly in terms of maximum acceleration, the short gears don't make any difference below 45 mph, and have an advantage from 45 to 73, then are at a disadvantage above that.

 

[Cap'n Carl]

On another subject, I'm surprised so many owners of supercharged NSX's like the short gearing. I would think the huge increase in available torque would make the short gears unneccesary, and only lead to spinning tires (or maybe spinning the tires is part of the goal? ).

I know it's a very different car, but my Solara was geared about perfect with the stock 200hp 3L v6, but now I wish it had taller gears with the supercharger. Traction is poor in fwd cars anyway, and with 270hp on tap, it's very hard to hook up in first. Also, first gear is over so quick that I feel I've missed out on some acceleration before the shift to 2nd.

I'm interested to hear what owners of sc'd cars think, especially if they've tried different ratios.

 

[LJSB]

Ken, I'm curious. Have you driven a NSX with short gears on track for 3 or 4 laps or otherwise?


NEVERMIND. In post#11 you said you had driven short gears on the track.

 

[SFNSXguy]

Ken, I'm curious. Have you driven a NSX with short gears on track for 3 or 4 laps or otherwise?

Yes, mine with 4.55 R&P (at Sears Point and perhaps at Laguna Seca, I can't remember)... which make some of his comments even more curious.

 

[TANTO]

If anyone is still looking for opinions, I did short gears and R R&P about half way thru my 18 year ownership. Having grown up with more powerfull cars, I needed the extra 3 tenths of a second in accelleration. The car pulls MUCH better out of slow second gear corners. This is perfect for those like me who do most of their driving arround town. First and second gear run out fast though so drivers that hit the road and drive the highway a lot will not like the gears. Also the short gears/R&P really messed up the car for Mid-Ohio track time. There are now two places where I have to shift to 4th for about 1/2 second. Before the gears the shift points would very nice for this track. If you track a lot, i would not go short. Running larger tires of course takes care of this situation somewhat. I personally though am quite happy with the shorties on the street.

 

[SFNSXguy]

If anyone is still looking for opinions, I did short gears and R R&P about half way thru my 18 year ownership. Having grown up with more powerfull cars, I needed the extra 3 tenths of a second in accelleration. The car pulls MUCH better out of slow second gear corners. This is perfect for those like me who do most of their driving arround town. First and second gear run out fast though so drivers that hit the road and drive the highway a lot will not like the gears. Also the short gears/R&P really messed up the car for Mid-Ohio track time. There are now two places where I have to shift to 4th for about 1/2 second. Before the gears the shift points would very nice for this track. If you track a lot, i would not go short. Running larger tires of course takes care of this situation somewhat. I personally though am quite happy with the shorties on the street.

If you had the 4.55 R&P you would be in 4th for quite a bit longer. The JDM/4.55 combo is just about perfect for a NA NSX at Mid-Ohio.

 

[latzke]

On another subject, I'm surprised so many owners of supercharged NSX's like the short gearing. I would think the huge increase in available torque would make the short gears unneccesary, and only lead to spinning tires (or maybe spinning the tires is part of the goal? ).

I have high boost CTSC and short gears with 4.55 R&P. Love it even when I'm at lower altitudes and thus getting full power. Tall gears still feel tall with sc, as I had that combo for a while. NSX weight transfer means wheelspin/putting down power not a concern at that power level even with narrower 1991 stock wheel/tire sizes.

 

[nsxtasy]

I've driven Mid-Ohio in approximately 40-50 track events over the years. The stock gears with the stock R&P is absolutely perfect for Mid-Ohio and most tracks, much much MUCH better than the short gears or short R&P. As noted above, on most of the track you can use second gear with the stock setup, which is shorter and gives much better acceleration than the third gear you are forced into using with the short/4.55 setup. There are a few tracks where the short setup is quicker, but Mid-Ohio is not one of them.

 

[stuntman]

It's all about torque multiplication!

The torque at the flywheel of the engine will go through the transmission (which will be multiplied by the gear's ratio) and then the differential (which also has an associated gear ratio that further multiplies torque).


So, for an example, not taking into account efficiencies:

Assume 210 lb-ft of torque at the crank/flywheel.

1st gear's ratio is 3.071:1, so after the transmission, the torque is multiplied to 614 lb-ft of torque.

The differential's gear ratio is 4.062:1, so the differential multiplies the total torque to 2,495 lb-ft of torque at the tires.


Now viewing the torque at the tire (expressed in lb-ft):

a) US (91-94)/4.06
b) US (95-96)/4.06
c) JDM/4.06
d) JDM/4.235

a) 2,495 - 1,403 - 999 - 786 - 626 = 6,309 total
b) 2,495 - 1,462 - 999 - 786 - 626 = 6,368 total
c) 2,495 - 1,586 - 1,137 - 839 - 626 = 6,683 total
d) 2,601 - 1,653 - 1,185 - 875 - 653 = 6,967 total

Now a JDM gear set with a 4.40 final drive:

f) 2,702 - 1,718 - 1,232 - 909 - 678 = 7,239 total


Now while these numbers aren't exact and will vary with RPM (as torque varies), the NSX has a fairly flat torque curve from 3-8K rpm at 175lb-ft of torque at the tire so the above numbers are somewhat in the ballpark.

As the final drive increases (4.06 to 4.44) and as each individual gear ratio increases (JDM gear ratio), the mechanical torque advantage increases and thus the car should be faster due to the torque at the tire increasing across the board.

EDITED with US 91-94 & 95-96

According to my gear chart (using a 245/40-17 tire)

a) US (91-94)/4.06
b) US (95-96)/4.06
c) JDM/4.06
d) JDM/4.235



MPH @ 8,000RPM:

a) 47 - 84 - 118 - 150 - 188
b) 47 - 80 - 118 - 150 - 188
c) 47 - 74 - 103 - 140 - 188
d) 45 - 71 - 99 - 134 - 180


MPH @ 6,100RPM (V-tec crossover):

a) 36 - 64 - 90 - 114 - 143
b) 36 - 61 - 90 - 114 - 143
c) 36 - 57 - 79 - 107 - 143
d) 34 - 54 - 76 - 103 - 137


MPH @ 3,200RPM:

a) 19 - 34 - 47 -60 -75
b) 19 - 32 - 47 - 60 -75
c) 19 - 30 - 41 - 56 - 75
d) 18 - 28 - 40 - 54 - 72


RPM after Redline Up-shift:

a) - 4,499 - 5,698 - 6,289 - 6,378
b) - 4,689 - 5,467 - 6,289 - 6,378
c) - 5,085 - 5,738 - 5,903 - 5,971
d) - 5,085 - 5,738 - 5,903 - 5,971


RPM Drop

a) - 3,501 - 2,302 - 1,711 - 1,622
a) - 3,311 - 2,533 - 1,711 - 1,622
b) - 2,915 - 2,262 - 2,097 - 2,029
c) - 2,915 - 2,262 - 2,097 - 2,029



The RPM drop and gear spread of the JDM gear set is more even than the US gear set which has a much larger RPM drop from 1-2, similar 2-3, then shorter 3-4 and 4-5 shifts (keep in mind for most tracks the 4-5 shift is probably irrelevant since there aren't a ton of tracks where a stock NSX would get up over 150mph). Because of this, the JDM gear set should be faster in the first 3 gears (up to 118mph) and then start to lose ground above 118 slightly. I like the JDM gear ratio.


Billy

 

[LJSB]

Stuntman,

So if I understand correctly, calculating the mph at the end of a gear (redline) does not adequately express the actual rate of acceleration.
It shows how fast the car is going when it reaches the end of the gear but not how long it took to get there?

 

[stuntman]

Stuntman,

So if I understand correctly, calculating the mph at the end of a gear (redline) does not adequately express the actual rate of acceleration.
It shows how fast the car is going when it reaches the end of the gear but not how long it took to get there?

Exactly. Increasing the torque multiplication from increasing the gear ratios WILL make the car accelerate faster. If the acceleration rate of the car was the same regardless of gearing (which is not true), and you just have to shift earlier due to shorter gearing - then shorter gearing would be slower.

But it's interesting to know where the shift points will be - especially for synchro transmission cars where shifting can result in a substantial time loss which can be almost insignificant (for a pro) or extremely damaging (for a less experienced/slower shifting driver). Depending on the track, if an extra shift is required and that shift takes longer than the rate of acceleration increase from the shorter gears, then it will be slower. But in many cases in racing, if an upshift would only be for a couple seconds, keeping the car at redline for a second or two to prevent a quick up-then-down shift, will only loose a couple thousandths of a second and still result in a net gain in the tenths. There will always be exceptions but for the most part, shorter gearing = faster.

 

[LJSB]

Thank you for this very well articulated explanation.
It always seemed odd that people were just looking at the mph at the end of the gear when I knew it was leaving out a important part of the formula.
Very nicely explained. I'm impressed.

 

[goldNSX]

Thank you for this very well articulated explanation.
It always seemed odd that people were just looking at the mph at the end of the gear when I knew it was leaving out a important part of the formula.

The math is pretty simple for guessing the advantage UNTIL you run out of rpm in a specific gear. I always loved to see different points of view being throwed in esp. as this mod is not easy to undo and every mod has pros and cons.

 

[stuntman]

The math is pretty simple for guessing the advantage UNTIL you run out of rpm in a specific gear.

Not necessarily. If you look at the time spent at full throttle around the entire track (where the shorter gearing will have a gain) will almost always outweigh the relatively small scenarios where you would would lose time from an additional shift. Even if a handful of shifts are created due to shorter gears or final drive ratios, it will rarely result in a slower net lap and most often result in a (possibly substantial) lap time improvment.

As I said in my last post, in a scenario where an additional upshift would be required at the end of a straight or between corners - just holding the car at redline for a second or two would result in less than a tenth of a second loss while the upshift might lose a couple tenths. But the benefit of the shorter gearing and faster acceleration across the board would be worth far more than this loss.

So the benefit of the shorter gearing will be much greater due to the torque improvement down all of the straights and all accelerating points on the track. Every second you are on the gas is a gain.


Billy

 

[SFNSXguy]

+1 what stuntman said.

 

[LJSB]

The math is pretty simple for guessing the advantage UNTIL you run out of rpm in a specific gear. I always loved to see different points of view being throwed in esp. as this mod is not easy to undo and every mod has pros and cons.

How is the finite math in this dissolved into a point of view?

 

[nsxtasy]

Yup, same thing hgunnerz and I were saying way back on page 2 of this discussion:

As H notes, the transmission gears act as a multiplier, but the torque doesn't vary much. With the NSX, the torque curve (torque at the crankshaft) is very flat, with less than 10 percent variation in torque between something like 4000 and 7500 RPM. So what matters is gearing, rather than engine torque. At any given speed (above 25 mph), whichever NSX has shorter gearing is faster.

However, no single gearing setup is shorter at ALL speeds; one gearing setup will be shorter at some speeds, while another setup will be shorter at other speeds. If much of a track is driven in a narrow range of speeds (such as the example of Mid-Ohio above, which favors the stock gears), it's easy to see which setup will be shorter at those speeds. But when a lap around a track has a wider range of speeds, it's less clear cut because one setup will have the advantage at some speeds while another setup will have the advantage at other speeds.

 

[stuntman]

Yup, same thing hgunnerz and I were saying way back on page 2 of this discussion:


However, no single gearing setup is shorter at ALL speeds; one gearing setup will be shorter at some speeds, while another setup will be shorter at other speeds. If much of a track is driven in a narrow range of speeds (such as the example of Mid-Ohio above, which favors the stock gears), it's easy to see which setup will be shorter at those speeds. But when a lap around a track has a wider range of speeds, it's less clear cut because one setup will have the advantage at some speeds while another setup will have the advantage at other speeds.

I believe you are still viewing the problem from an RPM standpoint (and HP relative to RPM) and not a torque at the tire from gearing standpoint.

Torque and torque from gearing dictates rate of acceleration. Just looking at RPM or shift points dosn't tell the whole story.

 

[goldNSX]

How is the finite math in this dissolved into a point of view?

new gear ratio/old gear ratio multiplied with new FD ratio/old FD ratio = more torque at the wheels.
For 2nd: 1.952/1.727*4.235/4.06 = 1.13*1.043 = 1.179 or 17.9 percent more torque at the wheels from 4-8k rpm and until you run out of rpm. You can see the same increase in Billy's calculation which is 1653/1403.
Thinking about it there's a second important effect. The longer gears esp. 2nd forces the engine at lower rpm where less torque is available (below 4k rpm) in some circumstances esp. hills. A shorter gear adds more than these 17.9 percent of torque just because the engine is faster in the max torque range.

I don't think Ken's point was on shifting points only, he stresses the acceleration times which are more important but surely dependant on shifting points.

 

[tbromley]

One thought here - Honda thought enough about the racing aspects of gear ratio and torque etc. to put the shorter gears in the NSX-R. I mean really guys if Honda thinks it makes a car faster and enough to put it in the more serious version of the car - why wouldn't anyone think that a tracker especially would benefit from the shorter gears.

I mean most of the time we all beg off to what Honda engineers thought and did. Why not now? What is this strange idea about track to track stuff - if you are a serious racer then I can surely understand changing stuff out for each individual track as a racer is on a circuit and it's definitely an advantage to have your car set up properly for each event but some one correct me if I'm wrong her - is there any race on any track where the NSX would run (that in itself may mean going to the history books) without a modded gear set or final drive????

I mean I hate to say it but there are two things going on in this thread which I believe are opposed to one another - street use vs. track use. I think that by the seat of the pants it is an overwhelming majority of guys that have made this switch that like it on the street. As far as the track is concerned I think it depends on how serious a track guy you are and how hard you run. Every video I've seen of guys running the NSX at Nurburgring or other Japanese comparo videos all the cars are running the short gears with perhaps different final drive ratios but I've never heard of anyone over in Japan or the ROW going back to the long gears. It's always the other way around.

I have nothing to compare this too as I have not driven a car with short gears but it just seems that from what I've read - everyone is pretty much in agreement that the shorties are definitely faster and torqueier on the street and it is a big difference. So it sounds like everyone is trying to convince Ken of this.....:biggrin: I haven't seen any decenting opinions other than his and that goes for track and street. The "I's" have it....:wink: