rebuilt transmission stock or short gears? Advice Please

[nsxtasy]

Wrong!

I guess thats why Honda put the 4.23rp and kept the short gears on the NSX-R..

No, they put the short gears on the NSX-R in the Japanese market to keep it the same as the non-R versions there.

 

[Alan C.]

Re: Wrong!

The information in this post was from flawed data. See nsxtasy's response below:

 

[nsxtasy]

The interesting thing on the stock 5 speed vs. the 2-3-4 short gears is the hp drop on the 2-3 shift. Assume no deceleration between shifts, there will be some loss of speed in reality. You get a drop of 8000 to 5700 for the stock box and a drop of 8000 to 5300 for the short box.

Re-check your math.

Stock gear ratios:
2nd 1.727
3rd 1.230

Short gear ratios:
2nd 1.952
3rd 1.400

RPM after upshifting from second (at redline) to third:
Stock gears 5698
Short gears 5738

In any case, you can optimize a gearbox for any particular turn, but most tracks, including Mid-Ohio and Putnam Park and VIR, have a variety of turns taken at a variety of speeds, such that any changes that are better for some turns are worse at others...

 

[Alan C.]

Re-check your math.

Stock gear ratios:
2nd 1.727
3rd 1.230

Short gear ratios:
2nd 1.952
3rd 1.400

RPM after upshifting from second (at redline) to third:
Stock gears 5698
Short gears 5738

In any case, you can optimize a gearbox for any particular turn, but most tracks, including Mid-Ohio and Putnam Park and VIR, have a variety of turns taken at a variety of speeds, such that any changes that are better for some turns are worse at others...

So my guess is that with a stock box you would only use 2-3-4 and never 5th. Maybe if you ran Road America CCW you might get there on the downhill pit straight.

After looking at the numbers I agree with nsxtasy that there appears to be no good reason on most tracks I frequent to go with the available short gears or R&P combo. The flat torque curve of the NSX is a different beast than I am used to. Looks like more would be gained from suspension and maybe a header/muffler combo on an early car. A large part of which would be offset by the cost of pulling the trans and installing gears.

 

[MikeC_587]

My answer is... if your NSX is completely stock and you have no plans to modify or perform upgrades, then just stick with the stock tranny.

or

if you plan on doing some modifications or have already begun, then I suggest you go with the 6 speed. I have and its one of my favorite upgrades and it might be the most expensive next to the Comptech Supercharger. BTW, when I did the 6 speed upgrade, I went with the Type R input shaft so I can retain the 5 speed clutch. I also went with a Jun lighten flywheel.

Good Luck,

Mike

 

[goldNSX]

@taf: what did you decide to go with?