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Short gear transmission

M

McLage

Registered Member
Joined
16 June 2010
Messages
18
Hello,
I have an european (France) 1992 NSX, 5 speed gearbox.
I find on a website the Honda JDM Short Gearset.
Japanese and US NSX's have not the same gear ratio and fitting this kit on US NSX allows better acceleration.
But I don't know if French gear ratio is the same that US gear ratio or Japanese gear ratio.
If I fit the short gear on my NSX, does that change anything ? will I have better acceleration or that doesn't chage nothing ?

Thanks
 
Last edited:
McLage said:
If I fit the short gear on my NSX, does that change anything ?
Click to expand...
If your 92 is still stock then you have the long gears like the US have. So their discussion is valid for 91-93 EU cars. Somewhere in 94, the EU cars had the JDM gears.
 
goldNSX said:
If your 92 is still stock then you have the long gears like the US have. So their discussion is valid for 91-93 EU cars. Somewhere in 94, the EU cars had the JDM gears.
Click to expand...
Ummm... I don't think this is true. My understanding is that the EUIM cars have the same gears as the USIM cars for all model years.

However, the gear ratios on the USIM and EUIM were shortened somewhat beginning with the '95 model year. For example, the ratio for second gear in the '95-96 is about one-third of the way from the '91-94 USIM/EUIM second gear to the '91-94 JDM second gear.

Also, the JDM "short" gears don't give better acceleration overall than the USIM/EUIM stock gears. Briefly, the JDM give better acceleration below 70 mph (where their ratios are spaced closer together), and the USIM/EUIM stock gears give better acceleration above 70 mph (where their ratios are spaced closer together).

For a stock '91 NSX:
0-70 mph (stock gears): 6.59 seconds
0-70 mph (short gears): 6.27 seconds
70-150 mph (stock gears): 31.19 seconds
70-150 mph (short gears): 34.79 seconds
 
Last edited:
nsxtasy said:
Ummm... I don't think this is true. My understanding is that the EUIM cars have the same gears as the USIM cars for all model years.

However, the gear ratios on the USIM and EUIM were shortened somewhat beginning with the '95 model year. For example, the ratio for second gear in the '95-96 is about one-third of the way from the '91-94 USIM/EUIM second gear to the '91-94 JDM second gear.
Click to expand...
Mmmh, I'm not sure about that. I'm getting confused now. :wink: There was a change in EU cars in 94 or 95 in the 5-speed. Do you say that the JDM gears are even shorter for 95/96? I don't have the EU 95/96 at hand.
The 2nd gear (3rd, 4th also) has been noticably shorter than in the previous models. I don't know to the rest of Europe but it was certainly in Switzerland.
The 91-93 stock EU gears are great on the German Autobahn but in a mountainous area the short gears add much more flexibility.
 
goldNSX said:
Mmmh, I'm not sure about that. I'm getting confused now. :wink: There was a change in EU cars in 94 or 95 in the 5-speed. Do you say that the JDM gears are even shorter for 95/96? I don't have the EU 95/96 at hand.
The 2nd gear (3rd, 4th also) has been noticably shorter than in the previous models. I don't know to the rest of Europe but it was certainly in Switzerland.
The 91-93 stock EU gears are great on the German Autobahn but in a mountainous area the short gears add much more flexibility.
Click to expand...

AFAIK the gears where the same for all 5 speeds, but the diff got changed to a torsen type, instead of the clutch type diff.
 
goldNSX said:
There was a change in EU cars in 94 or 95 in the 5-speed. Do you say that the JDM gears are even shorter for 95/96? I don't have the EU 95/96 at hand.
Click to expand...
Yes, the European gears are the same as the North American gears for all years. Beginning in 1995, the gear ratio for second gear only was shortened to 1.800 (from 1.727) in both markets. The ratios for gears 1 and 3-5 remained the same.

I believe the gears in the Japanese market stayed the same for all years '91-96, excluding the NSX-R model. The Japanese are shorter in second (1.952), third, and fourth.

You can look up all the ratios in the FAQ/Wiki here.

However, the '95-96 is the slowest of the NSX years, despite the (relatively insignificant) gearing change, because almost all cars of those years were the heavier NSX-T, without the increase in horsepower that accompanied the '97 and later models with the 3.2-liter engine.
 
Ken, I'm still not sure about the Wiki info stating that US and EU cars have the same gearing from 91 to 96. We've only a few 95/96 here and one guy was saying that he had the shorter gears like JDM from day one. So, I'm still a little bit confused.
 
I have a 96 UK car and can confirm that it has a full JDM gearbox. This has been checked against the car's VIN and the gearbox serial number too.. It may be for sale in the future as I am going to fit a 6-speed/4.23 unit in the next few months.

GoldNSX, do you have the pictures of your gearbox swap as I can't view them in your old postings?
 
Thanks for the confirmation. 95/96 EU cars have the JDM gears too. The Wiki is wrong on that. :tongue: Anyone wants to edit it? :)

I've a lot of pictures but the older I get...
I can send them by email.
 
goldNSX said:
Thanks for the confirmation. 95/96 EU cars have the JDM gears too. The Wiki is wrong on that. :tongue: Anyone wants to edit it? :)

I've a lot of pictures but the older I get...
I can send them by email.
Click to expand...

Thanks for the offer of the pics, just want to try and piece together your thread with pics. Can you see your old pics on your gearbox thread or is it just my computer?

I've PM'd an email address for pictures
 
From Honda EPC valid up to 2003
Select all for 5MT
Area 'KG' (in this case Germany)

1991: 23431-PR8-A00 GEAR COUNTERSHAFT SECOND
1992: 23431-PR8-A00 GEAR COUNTERSHAFT SECOND

1993: 23431-PR8-010 GEAR COUNTERSHAFT SECOND
1994: 23431-PR8-010 GEAR COUNTERSHAFT SECOND
1995: 23431-PR8-010 GEAR COUNTERSHAFT SECOND
1996: 23431-PR8-010 GEAR COUNTERSHAFT SECOND

1997: 23431-PR8-F00 GEAR COUNTERSHAFT SECOND (6spd)


1992: 23210-PR8-A02 MAINSHAFT COMP.
1993: 23210-PR8-020 MAINSHAFT COMP.
1996: 23210-PR8-020 MAINSHAFT COMP.
1997: 23210-PR8-F00 MAINSHAFT COMP.

Just to pass on this info.
Since the Honda EPC is a bastard to get info out off, i have no idea how valid this is, but i do know the dealers use(d) this for their inventory/ordering.
 
Last edited:
So it seems then that German-market NSXs had the US gear stack for 91-92 and then the JDM gear stack for 93-96.

DutchBlackNsx said:
From Honda EPC valid up to 2003
Select all for 5MT
Area 'KG' (in this case Germany)

1991: 23431-PR8-A00 GEAR COUNTERSHAFT SECOND
1992: 23431-PR8-A00 GEAR COUNTERSHAFT SECOND

1993: 23431-PR8-010 GEAR COUNTERSHAFT SECOND
1994: 23431-PR8-010 GEAR COUNTERSHAFT SECOND
1995: 23431-PR8-010 GEAR COUNTERSHAFT SECOND
1996: 23431-PR8-010 GEAR COUNTERSHAFT SECOND

1997: 23431-PR8-F00 GEAR COUNTERSHAFT SECOND (6spd)


1992: 23210-PR8-A02 MAINSHAFT COMP.
1993: 23210-PR8-020 MAINSHAFT COMP.
1996: 23210-PR8-020 MAINSHAFT COMP.
1997: 23210-PR8-F00 MAINSHAFT COMP.

Just to pass on this info.
Since the Honda EPC is a bastard to get info out off, i have no idea how valid this is, but i do know the dealers use(d) this for their inventory/ordering.
Click to expand...
 
Honcho said:
So it seems then that German-market NSXs had the US gear stack for 91-92 and then the JDM gear stack for 93-96.
Click to expand...
Yes, it seems. I was not sure what year it was. There are not many 93 here in Europe compared to 91/92 to confirm. Thanks to DutchBlackNSX for the part list. :)
 
If the 1993 partnumber is for a 2nd short-gear then yes. A different partnumber doesn't mean its a different part though. Might be from a different manufacturer. Or different tolerances, since there where problems with the 1992 gearbox (snapring), and they did a whole gearbox update (maybe?).

The reason i digged into it is cause its a lot of hear-say, and i rather see some facts.
 
Last edited:
I just installed short gears this weekend and I have the Honda part bags on my kitchen table. :D

23431-PR8-010 is the short 2nd gear.
23210-PR8-020 is the short mainshaft.

So, it's confirmed. 91-92 Euro cars have the US gears and 93-96 have the JDM gears.
 
Honcho said:
I just installed short gears this weekend and I have the Honda part bags on my kitchen table. :D

23431-PR8-010 is the short 2nd gear.
23210-PR8-020 is the short mainshaft.

So, it's confirmed. 91-92 Euro cars have the US gears and 93-96 have the JDM gears.
Click to expand...

Good info. When i get home i'll run the numbers for the other gears to see what happened with those in these years.
 
Gold,

Its a 1992 by VIN, but you know how it goes here in Europe. First registration in 1993, so its a 1993.
It does have shortgears though, after i was finished with it ;)
 
Mitch-

Here are the other short gear numbers from my parts bags:

Mainshaft Third Gear #23441-PR8-020
Mainshaft Fourth Gear #23451-PR8-010
Countershaft Third Gear #23471-PR8-000
Countershaft Fourth Gear #23481-PR8-000
 
I did a check on the other gears for 1993-1996 and they are identical. Together with the info from Honco, i'd say that in Europe in 1993 the shortgears where introduced up to 1996.

I had no idea. I realy thought we all had long gears.
To be honest, the short gears are not that good anyway. A light flywheel is a much better upgrade.
 
The reason why I ask if 1992 NSX have the short gear or not is because my gear box have the famous problem of the broken clip.
For december I will open gear box to repair. I ordered the JDM short gear and I will let you know if the gears are the same or not and I will make a report for the reparation of the gear box.
Does anyone know if there is anything to do for the clip don't broke ?
 
Looks like a lot of snap-ring NSX's have been delivered to Europe but with no goodwill.

If you don't want a broken snap-ring in the future you'll have to replace
- the gearbox housing
- the snap-ring of course
- the countershaft bearing

Get the service manual here online and have a closer look into it. It involves presetting the torque of the differential. Don't ask me how as I never did it before. :D Good luck!

If you gearbox is stock, no need to report back, it'll be definitly shorter. :D
 

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