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How to tell??

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I am trying to buy a tranny for my car that has short gears and the NSX-R final dive installed in it. My question is how do you tell if they are actually in there if the tranny is out of the car? If the tranny is in the car would I be able to notice a difference seeing as I have not driven my car in over 8 months and the my car has no tranny now so I have nothing to compare it to.
 

MJK

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Mph / Rpm
 
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White94 said:
Mph / Rpm
Yes, exactly. If you go to the FAQ section on Gear Ratios (in the Technical Info area), it shows the top speed in each gear at redline (8000 RPM). The last three columns show the ratios for the Japanese short gears with each of the three R&P options. The speeds aren't shown for the 4.235 R&P but they would be 43, 70, 97, 133, and 178.
 

MJK

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Keep in mind Japanese 'short gears' only change 2nd, 3rd and 4th. 1st and 5th are universal across markets. The R&P changes the final drive for all gears.
 

goldNSX

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earz0 said:
...My question is how do you tell if they are actually in there if the tranny is out of the car? ...
If the tranny you buy is out of the car you can't tell if the shorties and final drive are installed. When you have a chance to drive the tranny before installation it's most noticable in 2nd and 5th. If the final drive is installed the 5th should have 2250 instead of 2000 rpm driving 50 mph (reading the gauge). If the shorties are installed you have redline in 2nd at 70 mph instead of 81.
Check the tire dimension first as it influences the rpm reading.
 
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Why can't you tell? If you turn the input shaft some number of turns, then see how many turns the dif makes, do a little math and you can figure it out. You may need to turn the input shaft 50-60 turns, but you can figure it out.

It would be best if you just trusted the seller though:). Checking after it is in the car is only good if it IS shorties w/4.23. I would not want to be there if it was installed and you found it was not:(.

Here's some math to think about:

4th gear for shorties is 1.033 x R&P 4.062 = total ratio 4.196 to 1
4th gear for shorties is 1.033 x R&P 4.235 = total ratio 4.375 to 1

short 4th gear w/ 4.062 would be 50 turns input shaft to 11.916 turns dif
short 4th gear w/ 4.235 would be 50 turns input shaft to 11.429 turns dif

This shows nearly a 1/2 turn difference, definately enough to see with your eye. You just have to take your time and count accurately. I would prefer if someone could check my math,(and my logic:)) but you get the idea, you can figure it out.


HTH,
LarryB
 
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