Short Gear Review

[Honcho]

Not yet - but the short gears are driving me nuts - they are so good. :tongue:

The Type R diff parts consists of these two and a third part. Anyone know it's number?

The part on the left is actually a US part. You just use two of them in the NSX-R diff instead of one. The part on the right is the NSX-R stopper plate. It is a Japan part and is slightly thinner than the US plate. As Larry indicated, this is what is required to properly shim the diff to the correct ~110 lb/ft of torque. To address some of the concerns raised earlier, the car is not any more difficult to turn or park with the NSX-R diff. The manual steering and 275 series rear tires contribute much more to that than the diff.

As for the short gears, who knew I would stir up such a dust storm by saying I like the short gears? For a street driven NSX, they are far and away the best option. You feel like you have a 6-speed, I'm not kidding. For the track, it is debatable as to which gear stack is "better," and that debate is largely track dependent. However, I can say that the differences and the 2-3-4 shift don't seem that much wider or "worse" than the US gears. So for my personal view, I gained a large benefit on the street and a minimal loss, if any, on the track. For me, that made the upgrade worth the $. At an extra $1000 (even more money than the short gears!), I did not think that the 4.23 final drive was a good value add. I am extremely happy with my short gear/4.06 setup. Are me and Billy the only ones with this combo?

 

[goldNSX]

The part on the left is actually a US part. You just use two of them in the NSX-R diff instead of one. The part on the right is the NSX-R stopper plate. It is a Japan part and is slightly thinner than the US plate. As Larry indicated, this is what is required to properly shim the diff to the correct ~110 lb/ft of torque.

Thanks for the info. I didn't know about that. We only had one of each then and couldn't figure it out.

 

[sparky]

The part on the left is actually a US part. You just use two of them in the NSX-R diff instead of one. The part on the right is the NSX-R stopper plate. It is a Japan part and is slightly thinner than the US plate.

Where do you find NSX-R part details like this, is there a part list somewhere?

Assuming the part on right is in same location as P/N 41581-PR8-000 (item 11 in attached, from Acura diff parts lists) then the only difference in NSX-R P/N is the "J" in 41581-PR8-J00. Wondering if this is typical indication of NSX-R part numbers?

BTW part 41696-PR8-000 is item 15 in the diagram. So if I fit two stock parts per item 15 and one special item 11, this would be exactly NSX-R spec, or an approximation?

 

[nsxtasy]

Please list a couple of the "endless tacky insults" that you referred to, and at least one of the "juvenile phallic references" and a couple of the "similarly puerile (good use of your vocabulary, by the way) quips" in these topics -- I must have missed them!

Sure, here you go:

Okay. okay... I give up. Your dick IS bigger than mine!

Don't try reason, logic, math, experience or any other approach -- won't get you anywhere (see earlier posts).

SNORE!!!

Sorry, I dozed off there for a second.

Perhaps it's why you don't need a stopwatch to time your laps... that hourglass you always use is sufficient.

As well as the ones in this topic, the one I'm posting to now:

Lots of folks just hit the internet and copy what they find -- doesn't have to be the actual facts.

If you're one of those folks that think the JDM gears are better, it must just be a figment of your (our) imagination.

Now I understand that keN has "driven" on more tracks than Ayrton, and simply driving around a track is somewhat different than DRIVING around a track. With the OEM USA tranny you can drive around every track in the country. Hell, if you wanted to you could do them all in just 3rd gear (as keN suggested to a student in Phoenix).

(good use of your vocabulary, by the way)

 

[socalx]

can we please keep this on topic

 

[sparky]

can we please keep this on topic

I second that... the guts of this thread is a source of great NSX information in the NSX prime tradition, and there's more to come I'm sure, so let's not loose focus please

 

[docjohn]

I think those two have been bickering since before prime on what was a list serve of owners....just static to us old timers:wink:

 

[Larry Bastanza]

Where do you find NSX-R part details like this, is there a part list somewhere?

Assuming the part on right is in same location as P/N 41581-PR8-000 (item 11 in attached, from Acura diff parts lists) then the only difference in NSX-R P/N is the "J" in 41581-PR8-J00. Wondering if this is typical indication of NSX-R part numbers?

BTW part 41696-PR8-000 is item 15 in the diagram. So if I fit two stock parts per item 15 and one special item 11, this would be exactly NSX-R spec, or an approximation?

The "J00" indicates the part was FIRST used on the Japanese models, "00" indicates the part has not been revised. If it were "J02" it would have been revised twice, and originally used in a Japanese model.

There are a few J00 parts here in the US since they are updated parts.

Interesting thing is that the short gears are NOT J00 parts.

The 4.23 is all J00.

Regards,
LarryB

 

[Track Addict]

This thread made me lol at the hijacking that occurred.

Here is my take on short gears vs long gears

It is all very dependent on your setting, an extremely technical track (sears point) will MOST LIKELY benefit from the short gears and a higher R&P, whereas a high speed course (Willow springs "big track") you will be likely to find a few tenths with the stock USDM gearing.

In the end I think that it is up to each individuals needs/wants as far as their NSX is concerned. I drive Sears Point (Infineon...though I will never get used to calling it that) on average about four times or more a year. It is my favorite track (so far) and I will likely acquire the short gears and a higher ratio R&P to make MY track experience a more enjoyable (faster lap times) one. I also know that, after installing the short gears, my gearing for T-Hill won't be as suited for the NSX as T-Hill is more of a high speed track. (sacrifices sacrifices )

Do the homework yourself and spend YOUR money on what you have determined to be the best course of action. Have fun everyone!

 

[stuntman]

Wrong. Either horsepower or weight loss will give better acceleration than gearing changes.

It probably also depends on the gear change. I would probably agree with you if you are solely comparing the US to JDM gear ratio.

But if you are referring to changing final drives:

And it is my experience that MOST of the tracks I've experienced would best be served by the USIM stock gears with the USIM stock 4.062 R&P.

4.06 - 4.23 isn't nearly as big as a 4.06 - 4.55 gear change. Having your car geared to 180+mph (4.06) while never exceeding 150mph leaves a lot on the table in terms of efficiency and keeping the motor in the optimum powerband (from gearing) than having the final drive dictated by the top speed you intend on going. Ideally on a track you want to be at redline in the highest gear at the end of the longest straight. Here's a great quote/explanation:

"Changing the gear ratio in the final drive does two things. It changes engine speed relative to ground speed, and it changes the available torque at the drive wheels relative to engine torque. For achieving maximum accelleration you need the highest torque a the drive wheels, to which end you would want to increase the final drive ratio. But the magic red line on the tachometer (wherever you chose to paint it) dictates the highest speed allowable for the engine. The trick then is to use the highest gear ratio possible while not allowing the engine to run past red line at the fastest point on the race track. So on a short track where the car will not be moving so fast, it is advantageous to use a higher ratio final drive for improved accelleration. But for a longer track, especially with longer straightaways, the final drive ratio must be lowered enough to prevent over reving of the engine. To wit, it is common to swap out the final drive gearing between race dates."

Because of this, I don't think the 4.06 final drive is beneficial in most (especially NA) cases. In Grand-Am, the sanctioning body changes the competitiveness of cars (their outright SPEED) by changing their final drive ratios. The Mustang for instance was slowed down greatly by lowering their final drive ratio and making 5th gear almost useless and making 6th gear completely useless (since the car is now geared to over 200mph).

Not true. I use my car on racetracks where roughly 65-80 mph is the "sweet spot", the speeds that are often used through the corners and long stretches of the track (such as Mid-Ohio all the way from the end of the back straight to the chute). An NSX with stock gears can use second gear in those sections and is simply faster than an NSX with short gears which is stuck using third.

So you've tracked NSXs with both US and JDM gear sets. Other than Mid-Ohio (which you have repeated alot) which tracks have you been on that the US ratio is better at? While the US gear set can be better for certain tracks, i'm not convinced that the final drive is the best/fastest for almost any track in the US.

After a quick look:


Miller Motorsports Park (Outer loop): 4 turns <55mph

Mid Ohio (standard course): 4 turns <55mph

-after the back straight, you never get above 73mph (redline in 2nd gear for JDM gears) except for over the crest in Turn 10 and approaching Turn 11 which leads to Thunder Valley. Even here, upshifting won't slow the car down too much since you're not in the gear very long anyway before you're braking for T11. The apex of T-11 is <60mph and uphill. The higher rpm of the JDM 2nd gear would probably see an advantage over the US 2nd gear ratio coming out of this corner with better acceleration, and would probably see closer to redline in 3rd before Turn 12 compared to the US 3rd gear which will have ~10mph of unused potential and RPM that is not taken fully advantage of.

NJ Motorsports Park: 3 turns <50mph

VIR: 3 turns <50mph


Due to the frequency of lowspeed corners on various tracks, there is a pretty good argument for the shorter JDM 2nd gear when compared to the US gear ratio (both with 4.06 final drives).


***For most people, you should look at a few different things to help you decide what to do.

-Does cruising RPM matter to you? 4.55 will have a much higher RPM than a 4.06 for freeway use.
-Does a high top speed matter to you? 4.06 is geared to 180+mph. If you will never see that then it should be a irrelevant factor to you.
-Does outright speed on a track important to you?
-Is improved acceleration important to you?

For me:

1) Cruising RPM is important since I do a lot of freeway driving. I did not want the RPM to be very high. 2) Top speed does matter since I might drive the car in events or on tracks where I can reach these speeds. 3)Outright speed on track is important but a HUGE factor for me is that my car will be turbocharged with over 500hp and the longer 4.06 final drive will be advantageous with this much power. 4) Improved acceleration is important but again, due to the turbo, it is not directly comparable anymore.

Because of this, I decided to go with the JDM gear ratio and 4.06 Final drive for my turbocharged setup and MY intended application. If this was going to be an all-motor NA car and just for track use, I would probably go with the JDM ratio and a 4.55 final drive because the car would never see over 165mph.

 

[docjohn]

Billy I had the shorties and 4.55 for some years NA and the real speed limit was redline in 4th because shifting into 5th with 300 hp was useless....you just hit the aerodynamic wall....this was only a problem on one track pocono the long course....my speedo read 138,upshifting to 5th got me to about 145-148 but it took forever :frown:

 

[tbromley]

Thank you Billy! I can't wait to see Ken's response to this! Stay tuned - it just keeps getting better. Lots to learn here!

 

[latzke]

To address some of the concerns raised earlier, the car is not any more difficult to turn or park with the NSX-R diff. The manual steering and 275 series rear tires contribute much more to that than the diff.

Empirically speaking it does make the car harder to turn and I'm not talking about effort to turn the steering wheel. It makes it harder for the rear wheels to spin at different rates...necessary for turning (or rear differentials would be completely locked). To put it another way when turning the same diameter circle the lateral force exerted by the front tires to overcome the desire of the rear tires to stay the same speed (function of differential) is different.

I'm not sure how this effects at-the-limit handling (more under-steer or more over-steer under which dynamics) or how much. I'm sure it does have an impact, but I'm not a good enough driver for it to matter or to be able to weigh the pros/cons. Obviously Honda thought higher preset torque was better for the more-track-oriented Type-R...but maybe at a cost (less able to be handled by mere mortals?).

 

[stuntman]

Billy I had the shorties and 4.55 for some years NA and the real speed limit was redline in 4th because shifting into 5th with 300 hp was useless....you just hit the aerodynamic wall....this was only a problem on one track pocono the long course....my speedo read 138,upshifting to 5th got me to about 145-148 but it took forever :frown:

You will probably run into that problem to one extent or another regardless of gearing. With the JDM gearset, when you shift to 5th, you'll be at ~6,000rpm where the US gears would have you at ~6,350rpm. With your short gears, the only time "lost" is the time that it takes you to go from 6,000rpm to the drop point of the US gears (6,350). From that point on, the final drive and everything else is constant so your problem of rate of acceleration is due to aerodynamic drag and power/weight ratio. If you had a 4.06 with either transmission, it would take a lot longer to get up to that speed.

 

[W]

...And it is my experience that MOST of the tracks I've experienced would best be served by the USIM stock gears with the USIM stock 4.062 R&P.
...
I strongly recommend the stock USIM gears with their closer spacing for gears 2-5, rather than the short gears with the closer spacing of gears 1-2. It's the same reason the six-speed is superior to the five-speed; the stock five-speed gives you four closely-spaced gears to use on the track, rather than the three wider-spaced gears you're limited to with the short gears. More gears, with closer spacing, means that you can take better advantage of gearing in maximizing your rate of acceleration...

Wouldn't the stock US 5 speed with a higher ratio ring and pinion result in closer spacing of 2-5 at speed? This would seem to be a superior setup compared to the stock 5 speed with stock ring and pinion based on your line of reasoning in the second paragraph.

A little back on topic: I'd prefer the 6 speed gearing as it better matches how I use my car.

 

[sparky]

Interesting thing is that the short gears are NOT J00 parts. The 4.23 is all J00.

now that's good info!

still hoping for an answer to my other question ... about the exact NSX-R shim configuration?

also, how do I select from the different thickness shims that are available as spare parts? Or to ask this a different way: what is the number and thickness of all the shims in the diff when it left the factory (for NSX-R and stock NSX) ?

 

[Larry Bastanza]

now that's good info!

still hoping for an answer to my other question ... about the exact NSX-R shim configuration?

also, how do I select from the different thickness shims that are available as spare parts? Or to ask this a different way: what is the number and thickness of all the shims in the diff when it left the factory (for NSX-R and stock NSX) ?

There is no "thickness" to choose. You use the 41581-PR8-J00 stopper plate and two spring plates 41696-PR8-000, instead of the original 41581-PR8-000 stopper plate and one spring plate 41696-PR8-000.

Stopper Plate is a Japanese original Part
Spring Plate is a US original Part (probably ROW part), it is used in all markets 1991-94


HTH,
LarryB

 

[Honcho]

Thank you, Billy. You captured my thought process exactly and put it more clearly than I could have. I kept the 4.06 because I also do a lot of freeway driving and I want my 5th gear to stay overdrive.

It probably also depends on the gear change. I would probably agree with you if you are solely comparing the US to JDM gear ratio.

But if you are referring to changing final drives:


4.06 - 4.23 isn't nearly as big as a 4.06 - 4.55 gear change. Having your car geared to 180+mph (4.06) while never exceeding 150mph leaves a lot on the table in terms of efficiency and keeping the motor in the optimum powerband (from gearing) than having the final drive dictated by the top speed you intend on going. Ideally on a track you want to be at redline in the highest gear at the end of the longest straight. Here's a great quote/explanation:

"Changing the gear ratio in the final drive does two things. It changes engine speed relative to ground speed, and it changes the available torque at the drive wheels relative to engine torque. For achieving maximum accelleration you need the highest torque a the drive wheels, to which end you would want to increase the final drive ratio. But the magic red line on the tachometer (wherever you chose to paint it) dictates the highest speed allowable for the engine. The trick then is to use the highest gear ratio possible while not allowing the engine to run past red line at the fastest point on the race track. So on a short track where the car will not be moving so fast, it is advantageous to use a higher ratio final drive for improved accelleration. But for a longer track, especially with longer straightaways, the final drive ratio must be lowered enough to prevent over reving of the engine. To wit, it is common to swap out the final drive gearing between race dates."

Because of this, I don't think the 4.06 final drive is beneficial in most (especially NA) cases. In Grand-Am, the sanctioning body changes the competitiveness of cars (their outright SPEED) by changing their final drive ratios. The Mustang for instance was slowed down greatly by lowering their final drive ratio and making 5th gear almost useless and making 6th gear completely useless (since the car is now geared to over 200mph).

So you've tracked NSXs with both US and JDM gear sets. Other than Mid-Ohio (which you have repeated alot) which tracks have you been on that the US ratio is better at? While the US gear set can be better for certain tracks, i'm not convinced that the final drive is the best/fastest for almost any track in the US.

After a quick look:


Miller Motorsports Park (Outer loop): 4 turns <55mph

Mid Ohio (standard course): 4 turns <55mph

-after the back straight, you never get above 73mph (redline in 2nd gear for JDM gears) except for over the crest in Turn 10 and approaching Turn 11 which leads to Thunder Valley. Even here, upshifting won't slow the car down too much since you're not in the gear very long anyway before you're braking for T11. The apex of T-11 is <60mph and uphill. The higher rpm of the JDM 2nd gear would probably see an advantage over the US 2nd gear ratio coming out of this corner with better acceleration, and would probably see closer to redline in 3rd before Turn 12 compared to the US 3rd gear which will have ~10mph of unused potential and RPM that is not taken fully advantage of.

NJ Motorsports Park: 3 turns <50mph

VIR: 3 turns <50mph


Due to the frequency of lowspeed corners on various tracks, there is a pretty good argument for the shorter JDM 2nd gear when compared to the US gear ratio (both with 4.06 final drives).


***For most people, you should look at a few different things to help you decide what to do.

-Does cruising RPM matter to you? 4.55 will have a much higher RPM than a 4.06 for freeway use.
-Does a high top speed matter to you? 4.06 is geared to 180+mph. If you will never see that then it should be a irrelevant factor to you.
-Does outright speed on a track important to you?
-Is improved acceleration important to you?

For me:

1) Cruising RPM is important since I do a lot of freeway driving. I did not want the RPM to be very high. 2) Top speed does matter since I might drive the car in events or on tracks where I can reach these speeds. 3)Outright speed on track is important but a HUGE factor for me is that my car will be turbocharged with over 500hp and the longer 4.06 final drive will be advantageous with this much power. 4) Improved acceleration is important but again, due to the turbo, it is not directly comparable anymore.

Because of this, I decided to go with the JDM gear ratio and 4.06 Final drive for my turbocharged setup and MY intended application. If this was going to be an all-motor NA car and just for track use, I would probably go with the JDM ratio and a 4.55 final drive because the car would never see over 165mph.

 

[flaminio]

I love the passion in the threads like these. Moreso than anything else, it proves to me that the NSX is still alive despite Honda's best efforts otherwise.

 

[LJSB]

I kept the 4.06 because I also do a lot of freeway driving and I want my 5th gear to stay overdrive.

4.23 It's just matter of time Honcho. Just a clutch away I'd say.:biggrin: You won't be sorry.

The dark side is calling.

 

[Ty B]

700rpm delta at 70mph... pheeww, lotta overdrive there, heh heh. :tongue:

 

[nsxtasy]

So you've tracked NSXs with both US and JDM gear sets. Other than Mid-Ohio (which you have repeated alot) which tracks have you been on that the US ratio is better at?

Road America
Road Atlanta
Grattan
GingerMan
Putnam Park
Watkins Glen
Gateway International
Bridgehampton
Michigan International Speedway
Motorsport Ranch
Sebring
Autobahn Country Club
BeaveRun
Pacific Raceways
Texas Motor Speedway
Indianapolis Raceway Park

Of course, it depends on what you mean by "better". At all of these, the stock gears will be faster. They may not be easier to drive. For example, at GingerMan (before they added the extra turn last year), with its 10 turns and 1.8-mile layout, for fastest times with the stock gears, you'll be upshifting and downshifting between second and third 4-5 times per lap. With shorter gearing, you will be doing less upshifting and downshifting, because you won't be able to use second gear for much of the track, and you may find this easier to drive, but you'll be slower because you'll be using taller gearing on those stretches.

The "faster" tracks, like the "rovals", are generally faster because those high speeds are where the stock gears are spaced closer together than the short gears.

The only tracks where the short gears will be really advantageous are slow tracks (e.g. Waterford Hills) where you spend a significant amount of time under 60 mph and you don't have much in the way of long straights with their higher speeds.

Wouldn't the stock US 5 speed with a higher ratio ring and pinion result in closer spacing of 2-5 at speed?

No. The R&P gear does not change the ratios of the individual gears and thus does not change their spacing.

 

[Honcho]

Ha! The dark side will have to wait, as the $1000 I saved by keeping my 4.06 is going to pay to ship my NSX to Denver.

4.23 It's just matter of time Honcho. Just a clutch away I'd say.:biggrin: You won't be sorry.

The dark side is calling.

 

[stuntman]

At all of these, the stock gears will be faster. They may not be easier to drive.

I would have to respectfully disagree due to the (IMO) greater benefit in the lower sections of the track. While I don't think neither gear stack will be faster than the other at every or even most tracks, you will find that certain tracks favor one over the other. I don't believe there will be a clear winner. Regardless, this argument is heresay until someone back to backs both gear ratios in the same configuration car on the same day with data. Kind of pointless to argue further.

I will however say that a 4.23 or 4.40 will probably be better than the stock 4.06 at almost every track.




0.02

 

[Cap'n Carl]

I've no idea which ratio might be better at a given track, but higher ratios always FEEL faster, to everyone. As humans, it's hard to get past that natural bias.