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Gears & R&P stock or Comptech

Joined
10 February 2001
Messages
90
Location
Troy MI
Help? What is R&P (I thought it was the 5th gear). I was looking at options to get in VTEC range for city driving and like the Short Gears. I was thinking of leaving 5th stock which I know makes a gap between 4th and 5th large but leaves me with a high-way cruise gear for long trips. In option 3 below Comptech R&P makes 2nd and 3rd gear shifts redline at lower speeds which is what I want compaired to option #2 which has the same short gears but with stock R&P. So what is comptech R&P ? And how is it different from 5th gear. ( I know the 5th comes in 4.0 stock, 4.2 Z, and 4.5 basicly)

1.Stock R&P and stock gears - 2nd redlines at 85 mph or so, 3rd redlines around 118 or so
2.Stock R&P and Short Gears - 2nd redlines at 72 mph or so, 3rd redlines around 105 or so
3.Comptech R&P and Short Gears 2nd relines at 62 mph or so, 3rd redlines at 90 mph or so.
 
R&P makes your RPM go higher/mph in every gear. The transmission drives the R&P then the wheels. So with R&P is like having gears on every gear which still doesn't solve the 1-2 shift unless you get short gears as second gear is just too long.
 
Is there anyway to change only first, second, and third gear to the short gears and leave 4th and 5th stock?
 
Is there anyway to change only first, second, and third gear to the short gears and leave 4th and 5th stock?

The short gears are only 2nd, 3rd, and 4th. 1st and 5th only come in the stock gearset. Although (as pointed out above) you wind up achieving shorter gearing in ALL gears if you put in a higher-numerical-ratio (shorter) ring and pinion gear.

There's a lot of info on this in the FAQ section on "Gears" in the "Performance" heading.
 
Ok I understand but is it possible to change only second gear to the shortie set and leave 1,3,4,5 stock? I am saying this because second is the only gear that actually helps you cause 1st is the same as stock, 3rd is almost identical, and 4th and 5th are shorter in the stock gear set than in the shortie gear set.
 
I just had my tranny work done by Mark Basch and had him install the 2nd,3rd & 4th short gears along with the stock 1st & 5th. He also recommended going with the 4.55 ring & pinion. As long as you have the tranny apart you might as well install the new R&P along with a performance clutch and light weight flywheel. This combination is a vast improvement over stock. I think that you would waste your money just going with the short gears and the stock ring & pinion.
 
Brad what is the basic cost of getting the short gears and R&P ? Do they sell you the parts or rebuild the tranny and swap it out?
Labor hours? I hear the only down-side is a whine? Or have they fixed the nosie in the gears by refining them, since early models I read about at the nsxprime FAQ section.
 
Brad:

If you have short gears AND R&P, what does your car feel like above 100mph? I mean, the numbers seem to show that your car will be much slower at triple digit speeds.
 
Originally posted by NSXocto:
Brad what is the basic cost of getting the short gears and R&P ? Do they sell you the parts or rebuild the tranny and swap it out?
Labor hours? I hear the only down-side is a whine? Or have they fixed the nosie in the gears by refining them, since early models I read about at the nsxprime FAQ section.

Check with Dali Racing about the trannies. Mark offers many combinations. www.daliracing.com
I have a slight whine at idle with the 4.55 but it's hardly noticable. The labor will take approximately 10 hrs.
 
Originally posted by JChoice:
Brad:

If you have short gears AND R&P, what does your car feel like above 100mph? I mean, the numbers seem to show that your car will be much slower at triple digit speeds.

The car feels much lighter on it's feet and will reach 150 mph about 2 seconds quicker that a stock geared NSX. Top speed is around 165 mph.
 
Brad: (popular guy tonight)
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Any downside? to R&P of 4.5 instead of half-step at 4.2 Z ? Does the car feel too wound-up for tooling around town?

I agree the 4.0 stock R&P would be a waste if your going to have the short gears installed anyway.

Are the extra steps of a LightWeight Flywheel and special clutch a "must do" in your opion?
 
Ok I understand but is it possible to change only second gear to the shortie set and leave 1,3,4,5 stock?

It's possible, but not desirable. The stock gears contain a bigger gap between 1st and 2nd than with the other upshifts, dropping you to a lower power point in the rev band. The idea behind the short gears is to even out the spacing between the gears. If you only swapped the second gear, you would just be moving that big gap to the upshift from 2nd to 3rd.

I am saying this because second is the only gear that actually helps you cause 1st is the same as stock, 3rd is almost identical, and 4th and 5th are shorter in the stock gear set than in the shortie gear set.

Wow, lots of misinformation on this topic tonight. Go to: http://www.nsxprime.com/FAQ/Technical/gearratios.htm and compare the column that says "U.S. 91-94 5-speed" (these are the stock gears) with the column that says "Japanese 91-94 5-speed" (these are the short gears) and you'll see that the short 3rd is shorter (higher number ratio shown) than the stock 3rd, the short 4th is shorter than the stock 4th, and there is no such thing as a short 5th gear.
 
Originally posted by NSXocto:
Brad: (popular guy tonight)
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Any downside? to R&P of 4.5 instead of half-step at 4.2 Z ? Does the car feel too wound-up for tooling around town?

I agree the 4.0 stock R&P would be a waste if your going to have the short gears installed anyway.

Are the extra steps of a LightWeight Flywheel and special clutch a "must do" in your opion?

The car feels great around town with the 4.55 and not too wound up. It winds up fast in to the VTEC for instant response. Much quicker than the stock gearing and r&p and heavy stock flywheel.
 
Much quicker than the stock gearing and r&p and heavy stock flywheel.

Yes, the shorter r&p and gearing will feel quicker. It gives you the perception of speed because you reach redline sooner. However, you reach redline at a lower road speed, and as soon as you upshift, you are then accelerating slower than you are with the stock gears, because you are in a higher gear. One gear setup accelerates faster at certain road speeds, and the other accelerates faster at other road speeds. That's why when you look at the "What are the numbers" chart in the "Gears" section of the FAQ, you don't see huge differences from one gearing setup to another. Overall acceleration really isn't improved with the shorter gearing, and as you can see, the shorter gearing is actually two seconds slower from 0 to 140.

So the question becomes: Do you want to (a) go faster, or (b) feel like you're going faster? If you actually want to GO faster, you'd be better off spending money on power mods, like the traditional I/H/E or a supercharger. On the same chart in the "Gears" section, you can see how adding 20 hp will outperform any gearing change you make.
 
NSXtasy might be right.

I bang around town as a daily driver and want to spend as much time in VTEC as I can, and use 1st, 2nd, and 3rd gear. If I get a ticket from 0-90mph I'll pay it.

I don't know what to do with a car at 85-150mph (to get to VTEC in play with the gears) execpt go to jail
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I will also drive up and down the strip at 20mph with the top off and try to meet some gals
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I wish I lived in a state like Texas or Germany. Where I could go fast! But I don't
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Sure I'll do a few track events a year but that will be very little percent of my seat time.

How do the rest of you use the car?
 
How do the rest of you use the car?

My usage is something like this:

1/3 - On the track
1/3 - Driving to and from the track
1/3 - Driving to and from NSX Club events

I have another car that I use as a daily driver (and occasionally on the track also).
 
NSXTACY, I have a question I think you can answer. I'm a bit confused on why an NSX would not gain more in a quick 0-60 sprint with the gears and R&P. I still don't know much about NSXs, but the numbers on the FAQ support what you are saying. I am wondering why it doesn't make MORE of a difference.
Back when I still had a vette, I upgraded from a stock 3.42 differential to a 4.02 (or something around that number, I forget). Although I'm sure I lost top speed, that kind of an upgrade cut 4 to 5 tenths of a second off my 0-60 time on a Gtech, consistently. That's a huge difference. I know that it's not 100 percent accurate, but the difference was obvious and consistent. I know others who added a torque converter to that setup and gained an even bigger performance increase.
Are the gears and R&P for the NSX somehow fundamentally different than changing out the differential in a vette.
I was actually considering doing gears someday for performance reasons only, but in light of this new info I may not. I already have intake and exhaust, and will be doing headers shortly.
I'm just interested to see why.
Thanks
 
you know, one of these days I'm going to get your handle right. It's just that I used to have a plate XTC so it's kind of a habit. sorry.
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Here's a good way to visualize it.

Think of a graph in front of you with 'speed' on the horizontal axis, and 'rpm' on the vertical axis.

Now, put your right hand in front of you. That symbolizes the stock US 5 speed. See the gap between your thumb and pointer?

Now, stretch all three middle fingers torward your thumb, leaving your pinky spread apart.

That symbolizes the oem short gears.

Now, remembering that 'graph', shift your hand to the left to symbolize placing a higher R&P (4.23, 4.55). Notice how you are faster to a given RPM than the 'stock' R&P? But your top speed is lowered?

Hope that makes sense.

-- Chris

------------------
Chris Willson
www.ScienceofSpeed.com
www.NSXClassifieds.com

[This message has been edited by ScienceofSpeed (edited 22 March 2001).]
 
After quite a few strange looks from co-workers walking by my office, I think I have visualized your graph. While I understand what you are getting at here, the question I'm waiting to hear answered is... Is the car quicker to the lower top speed with the "shortie" gearing and R/P set or does it just feel quicker (mentioned above) when it is actually slower? I try not to go 180MPH around here, but I would love to be able to get up to 100MPH quicker than I do now.

I have been considering one of the Dali tranny kits, or looking at a 6-speed conversion.

------------------
Brian
Austin,TX
95 NSX-T Black/Black
 
If the changed made is the R&P only, the car will be faster to reach any given speed.

To give an example, it's almost the same principle as accelerating from 15 mph to 45 mph using first gear or second gear. The first gear will be faster in reaching the 45 mph than the 2nd gear. Even though the rpm at given speed in 1st gear is higher than in 2nd gear
 
I am wondering why it doesn't make MORE of a difference.

Now, THAT’S an interesting question. Here’s my guess as to why the NSX might be different from your Vette in this respect.

There are a couple of general design principles that differentiate the NSX from other sports cars, and result from its use of the VTEC system to have that extra lobe kick in above the VTEC crossover point. One is that the torque curve is relatively flat from idle to just short of redline (as you can see from the diagram http://www.nsxprime.com/FAQ/Technical/images/97/97NSXPowerCurve.gif ). The other is that the NSX redline is much higher than non-VTEC cars.

Next thing to note is a concept that applies to all cars: what makes the car accelerate is TORQUE AT THE WHEELS. This is equal to torque at the crank, multiplied by gearing. For maximum acceleration, you want to maximize torque at the wheels. For example, when you’re determining your shift points when accelerating, with some other cars you need to pick the point when the torque curve falls off enough that torque at the wheels in the lower gear is equal to that at the higher gear (IOW, even after multiplying torque at the crank for the gearing effect). Not so with the NSX. With our cars, you can keep them in gear almost up to redline, so that the optimal shift points are in the 7500-8000 rpm range in every gear. IOW as a general rule, your NSX acceleration is maximized by keeping the transmission in the lowest gear you can. And within a given gear, your torque at the wheels doesn’t vary all that much. All of this explains why the NSX is as quick as it is, despite relatively low torque numbers: because its torque is maintained up to higher rev points than other cars, so that the NSX can stay in a lower gear while other cars would need to upshift, lowering their torque to the wheels. This also explains why horsepower (torque times revs) is a more accurate reflection of the NSX’s capabilities than torque: because it reflects the NSX’s ability to maintain torque as the revs rise higher and higher, so that it can be used as a measure of power and as a proxy for torque at the wheels.

I think that the THEORY behind the short gears is slightly different from the ACTUAL TRUTH. What do I mean by that? The theory is that the short gears provide greater acceleration because the stock gears have too wide a gap between first and second, dropping you out of the VTEC range (because after the upshift, your revs are 4433 rpm, whereas the short gears have revs at 5013 rpm after upshifting). However, as you can see from the torque curve graph, the torque at these revs isn’t drastically different from the torque at higher revs. As for the actual truth, I suspect that there is a bit better acceleration in the short second gear than the stock second gear, but that this is primarily due to the gearing multiplier (the conversion from torque at the crank to torque at the wheels) rather than the size of the gap between the gears - IOW the same thing that makes a higher-numerical-ratio ring and pinion gear accelerate quicker in a given gear. Furthermore, with the shorter gears, the PERCEPTION of the additional acceleration is exaggerated, because your revs are higher (therefore louder) and you are reaching redline quicker (although at a lower road speed). Regardless of the additional impact of your perceptions, your acceleration will indeed actually be better in the short second than in the stock second...

...UNTIL YOU UPSHIFT. With the short gears (or R&P), you have to upshift at a lower road speed. And immediately after the upshift, you start losing the benefits, because your acceleration will be faster with the stock second gear than with the short third gear. Again, for the exact same reason - at those road speeds, you have "shorter gearing" (the conversion of the relatively constant torque at the crank into torque at the wheels) with the stock gears.

Let’s look again at the chart, "What are the numbers" (in http://www.nsxprime.com/FAQ/Performance/gears.htm ) and see how this comes into play. Compare the numbers between the stock five-speed ("baseline") and the short gears with stock R&P (Japanese 5-speed). You can see that acceleration from 0-40 is the same (2.92 seconds) with both gearsets - no surprise, since first gear is identical between the two, and the first upshift is around 40 mph. Accelerating from 40 to 70 mph, the short gears are significantly quicker (3.68 vs 4.07 seconds, after you subtract the 0-40 time from the numbers in the table). But accelerating from 70 to 80 mph, the stock gears are significantly quicker (1.47 vs 1.92 seconds) even after accounting for the .3 seconds that it takes to complete the shift. The reason for this is that the stock gears are in second gear while the short gears shift up to third. Bottom line is that there ARE advantages of one set of gears, but only at certain road speeds, and those advantages are negated at other road speeds. Overall it winds up being close to a wash.

I am not familiar with the Vette, so I really can’t speculate on the improvements due to gearing in that car. It could be that the torque curve drops off and the gearing helps keep the car within the power band. It could be that the gearing improvements are only at certain road speeds, just like with the NSX. It could be that the differences are exaggerated by perceptions rather than what would be reflected in actual measurements. I just don’t know.

Hope this makes sense and is helpful. Sorry for the long-winded reply.
 
That was an excellent reply and very informative. Thanks for the info. I understand better exactly what the gears do for the NSX and where the advantages and disadvantages are. In fact, I think your explanation may be a good candidate for being added to the FAQ to help the explanation. Lud???
 
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