Gear Ratios

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What are the gear ratios and speeds at 8,000 RPM (redline)?

Gear ratios are computed by simply dividing the number of teeth on your spur gear ( larger gear) by the number of teeth on your pinion gear (smaller gear).

Gear

US '91-'94
Ratio - MPH

US '95-'96
Ratio - MPH
US '97+
Ratio - MPH
Japan '91-'94
Ratio - MPH
-R '91-'94 Japanese
'91-'96

R&P

4.062

4.062 4.062 4.062 4.235 4.55*

1

3.071 - 45

3.071 - 45 3.066 - 47 3.071 - 45

3.071

3.071 - 41

2

1.727 - 81

1.800 1.956 - 74 1.952 - 73

1.952

1.952 - 65

3

1.230 - 114

1.230 - 116

1.428 - 102 1.400 - 101

1.400

1.400 - 90

4

0.967 - 144

0.967 - 144

1.125 - 130 1.033 - 139

1.033

1.033 - 124

5

0.771 - 186

0.771 - 186

0.914 - 160 0.771 - 186

0.771

0.771 - 166
6 <none> <none> 0.717 - 202 <none>

<none>

<none>

R 3.186 3.186 3.186 3.186 3.186 3.186

R&P stands for Ring and Pinion.  It's the final drive gear for the transaxle -- what is in the differential ("rear end" or "third member") on a conventional front-engine/rear-drive car.

European gears are the same as US and Canada for all model years.

* The 4.55 R&P is the only non-OEM one listed here. It was made by Comptech (now called CT Engineering) but is no longer available.

RPM Drop During Upshifts

Shift '91-'94 US
5-speed
'97-'98 US
6-speed
'91-'96 Japanese
5-speed
1 -> 2 4499 5106 5085
2 -> 3 5698 5837 5738
3 -> 4 6289 6266 5903
4 -> 5 6378 6500 5971
5 -> 6 n/a 6330 n/a

[KS] You can see from the figures above why the stock '91-94 5-speed has reduced acceleration right after the 1-2 upshift; it's because the revs drop down to 4499, so the gearing is taller, resulting in slower acceleration. The  6-speed and the Japanese ("short") gears both get around this by having a lower second gear (i.e. the ratio is numerically higher). Thus the ratio of second gear is closer to first, and the revs only drop to around 5100.

Both the 5-speed and the 6-speed do a great job of keeping the revs high once you get above 100 mph (above third gear), by not letting them drop below the high 6200's, so you have the acceleration advantage of the shorter gearing, whereas the Japanese gears force the revs to drop to around 5900 with both of the subsequent upshifts, reflecting taller gearing after the upshift. The numbers show significantly worse acceleration over 100 mph for the Japanese "short" gears than either the stock 5-speed or the stock 6-speed. The 6-speed would seem to provide the best all-around combination, because it doesn't drop revs too badly at any of the upshifts, so it's using nicely short gearing all the time. It combines the  faster acceleration under 100 mph of the Japanese gears with the faster acceleration over 100 mph of the stock 5-speed gears.

[BJ] Simply put, gearing is torque multiplication. While RPM is important (higher the RPM = higher HP levels in the NSX), the flat torque curve of the NSX combined with the mechanical advantage of the JDM gear ratio being shorter (numerically higher), the JDM ratio should accelerate quicker throughout the speed range. It's NOT all about the RPM drop but rather about torque multiplication. If you look at the ratios, the JDM ratio is always shorter than the US until 5th gear, where if anything, that will be the only point where the lower RPM might hurt acceleration due to the same gearing, but it might be more than overshadowed by the acceleration gained in the first four gears.

Gear Ratios for Automatic Transmission (all years)

Gear Ratio
1 2.611
2 1.466
3 1.025
4 0.684
R 1.909
Final Drive 4.428
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