JDM 5-spd NSX and 4.23 NSX-R gearsets

[bazza]

Following on from your threads about gearsets I thought I best offer you lot the option of changing to JDM short gear sets.

23210-PR8-020 - mainshaft
23441-PR8-020 - 3rd mainshaft
23451-PR8-010 - 4th mainshaft
23431-PR8-010 - 2nd countershaft
23471-PR8-000 - 3rd countershaft
23481-PR8-000 - 4th countershaft

Kit price is £480 delivered.

..or 5-spd NSX-R final drive kits

41581-PR8-J00 - STOPPER PLATE
21173-PR8-J00 - OIL PUMP GEAR
23220-PR8-J00 - PINION GEAR
41233-PR8-J00 - RING GEAR

Kit price is £562 delivered.

[Senninha]

Hi Barry,

what about the NA2-R final drive? can you get this?

What advise would you give ref a clutch replacement (not needed yet but doing homework)
- Fast road usage
- like OEM pedal weight

I understand that a lighter flywhel can assist the speed at which the engine revs? is there a lightened version for OEM clutch?

As I say, theres no rush, so when you get a spare 5 mins ;)

regards, Paul

[AR]

Any leads who can install those?

[Senninha]

Any leads who can install those?
Hi Ary,

PLans motorsport have a gearbox specialist that does work for them on road and track 'boxes. When I asked about the final drive change they said that they would check the full 'box while it was out, ie bearings etc.

If I did this it would be when the clutch becomes due.

What would be useful to kow is the impact on performance, ie acceleration, cruising etc with the different gearing ... anyone?

regards Paul

[AR]

Paul,

I can comment from driving a short ratio box NSX-R and the difference for the 5 speed is awesome. On your car I am not sure what it would do, but it will knock dow top speed.


Good article here:

http://www.nsxfiles.com/nsx_shortgears.htm

Hope it helps,

AR

[markc]

As discussed on the thread as to whether MY'96 cars had the JDM gears or not, the 6spd cars have very similar gearing in 1st/2nd/3rd then lower gearing for 4th and 5th then of course 6th with a theoretical top speed of 200mph!

Of course there's no way the the standard engine will pull the standard 6th gear ratio to 200mph so fitting the lower NSX-R diff ratio will actually increase top speed, in 6th gear anyway. It should also help acceleration in each gear a touch, the flipside being that you have to change more often.

Here's that other thread... http://nsxcb.co.uk/testvb/showthread.php?t=3495&highlight=short+gears&page=4

A lighter flywheel will help the engine gain and lose revs more quickly particularly when de-clutched. You won't notice much if anything climbing through a gear but it should help with faster gearchanges. You could have problems with the engine stalling when you de-clutch to stop, at junctions etc, as the faster rev decay catches out the standard ingnition/fueling.

Mark

[Senninha]

A lighter flywheel will help the engine gain and lose revs more quickly particularly when de-clutched. You won't notice much if anything climbing through a gear but it should help with faster gearchanges. You could have problems with the engine stalling when you de-clutch to stop, at junctions etc, as the faster rev decay catches out the standard ingnition/fueling.

Mark
Hi Mark,
Is there a lightened fly for the OEM clutch? My understanding that there is not. I've read several threads about aftermarket clutch, the consesus appearing to point to OEM clutch for NA cars, based on pedal force, judder, noise etc.

So fitting the 4.235 final from the 02 NSX-R to our 6spd will improve accel, poss top speed where permitted etc. Q: what does it do to revs for 80mph m'way work please?

Whilst I dont need a clutch at present, the $$ rate would make it a sensible time to put one on the shelf, together with the new gearing which would be a one time job.

regards, Paul

[markc]

I think you're right, there no obvious aftermarket lightweight flywheel available. I replaced the clutch in my car last year and also weighed up (no pun...) the pros and cons of aftermarket vs oem at the time. I went oem and retained the original flywheel.

I see no reason why you couldn't have the factory flywheel lightened though? Provided you knew what weight you wanted to end up at and the engineering w'shop that did the work were used to this sort of thing you should get the best of both oem pedal pressure/take-up smoothness and faster engine response worlds.

Regarding the effect on cruising, the new diff is approx 4% "shorter" than the stock one so my logic says it should make the engine 4% higher revving? I could be wrong, it happens very regularly :)

Working back, I make it that the standard top gear ratio gives you 25.25mph/1000 revs... so 80mph is 3,168rpm... and with the NSX-R diff 80mph will be 3,300rpm ie just 132 revs differant.

There's probably lots of rounding errors in those calculations but I think it shows the differance isn't huge, either in stronger acceleration or less relaxed cruising.

Cheers

Mark

[AR]

Mark how will the R ratio increase top speed?

[markc]

By allowing the engine to "pull" 6th gear better.

Peak power is attained at 7,100revs. Standard gearing of 25.25mph/1000rpm gives 179.275mph

Despite claims elsewhere, I think that (180mph) is on the high side for a sub 300hp car even allowing for the reasonable drag coefficient (0.32) and low frontal area.

Factory spec says top speed is 170mph which means it doesn't pull peak power in top gear.

With the NSX-R diff, peak power would give 172.1mph which is closer to the claimed top speed.
The power curve of the 3.2 Ltr engine is quite flat between 6,500 and 7,500 giving it a fighting chance of running to peak power and even beyond it eg 180mph is at 7,425rpm

With the standard diff, 180mph is 7,128rpm which is VERY close to peak power BUT would it actually get there?
It's very unlikely to run beyond peak power and using the same example as above 7,425rpm would equate to 187.5mph!!!

The NSX-R diff ratio looks to me to hit a sweeter spot for attaining a higher top speed and my suspicion is that on a flat and level road a 3.2Ltr 6spd car will go faster with the R diff ratio than the standard one.

As I said before tho'... I've been wrong plenty of times before :)

Mark

[AR]

Mark but haw do we explain how several people on Prime and our own Kowalski have attained GPS verified 180 mph with 5 speed ones ?

BTW the NSX-R with the 5 speed Mugen tuned box and LSD will top out way before 168 mph!

Cheers,

AR

[TheSebringOne]

Paul, this might be of interest to you as I have kept it in my Fleabay! Think its the one Paul NSX2000 or WhyOne posted earlier this year? HTH

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&ih=012&sspagename=STRK%3AMEWA%3AIT&viewitem=&item=220114660275&rd=1

[Senninha]

Thank You James :thumbsup:

[markc]

Re the 180+mph claims, many of these are achieved by slightly modded cars and often on slight downhill runs, but anyway there may be another explanation...

Gearing for all non NSX-R 5spd cars is 23.25mph/1000rpm ie lower than either standard or NSX-R ratio 6spd'ers.

This gearing will provide 165mph at the 7,100rpm peak power. 180mph wouldn't be hit until 7,742rpm by which time power has tailed off significantly!

Despite the slightly narrower peak power band of the 3.0Ltr engine, peak power is supposed to be identical and therefore this combo is perhaps more likely to achieve 7,100rpm and a little beyond in top (5th)?

Using the previous example revs of 7,425rpm this would equate to 172.6mph

In terms of getting to these sort of speeds quickly ie before the road runs out, the 6spd cars have a big advantage with their significantly lower 4th and 5th gearing.

Back to the 5spd with NSX-R diff for a moment, it would carry 22.25mph/1000rpm. 7,100rpm would equate to 158mph, 7,425rpm gives 165mph and 180mph would need 8,090rpm. Perhaps a touch undergeared for top speed but that's not what the NSX-R is all about.

Personnally I still think 180mph is on the high side for a stock NSX engine whatever the gearing but I'm certainly not going to argue with GPS.

Cheers

Mark

[simonprelude]

Me either, must remember to have camera ready next time mine has a fit and tells me I am doing over 350mph :)



Personnally I still think 180mph is on the high side for a stock NSX engine whatever the gearing but I'm certainly not going to argue with GPS.

Cheers

Mark

[bazza]

Mark but haw do we explain how several people on Prime and our own Kowalski have attained GPS verified 180 mph with 5 speed ones ?

BTW the NSX-R with the 5 speed Mugen tuned box and LSD will top out way before 168 mph!

Cheers,

AR

Yep.. 172mph indicated, real speed 161mph..
Mugen LSD with 4.4 final drive.. :)

[NoelWatson]

By allowing the engine to "pull" 6th gear better.

Peak power is attained at 7,100revs. Standard gearing of 25.25mph/1000rpm gives 179.275mph

Despite claims elsewhere, I think that (180mph) is on the high side for a sub 300hp car even allowing for the reasonable drag coefficient (0.32) and low frontal area.

Factory spec says top speed is 170mph which means it doesn't pull peak power in top gear.

With the NSX-R diff, peak power would give 172.1mph which is closer to the claimed top speed.
The power curve of the 3.2 Ltr engine is quite flat between 6,500 and 7,500 giving it a fighting chance of running to peak power and even beyond it eg 180mph is at 7,425rpm

With the standard diff, 180mph is 7,128rpm which is VERY close to peak power BUT would it actually get there?
It's very unlikely to run beyond peak power and using the same example as above 7,425rpm would equate to 187.5mph!!!

The NSX-R diff ratio looks to me to hit a sweeter spot for attaining a higher top speed and my suspicion is that on a flat and level road a 3.2Ltr 6spd car will go faster with the R diff ratio than the standard one.

As I said before tho'... I've been wrong plenty of times before :)

Mark

Mark,

From what I've read, the 02 standard has a claimed 175 top end (I find that hard to believe) whereas the 02 Type R is only 168/170

http://www.autozine.org/Graveyard/html/Honda/NSX.html
http://www.supercars.net/cars/2456.html

[Rob_Fenn]

I'd be interested to know how the NSX-R (NA2) uprated diff compares to the aftermarket ones? Is there a consensus on what is best?

[markc]

Rob, I'm guessing you mean the lock-up spec/characteristics of the NSX-R LSD rather than the gearing? That's a whole other story :)

W.R.T the stock '02 car running to a higher vmax than the '02 NSX-R, it may be because the new aero parts on the NSX-R raise the drag but I personally doubt that would overcome it's "sweeter" gearing.
If you accept those numbers (175mph and 170mph) the '02 still doesn't pull peak power in top whereas the R gets very close to it.
IF the R really does have more power it should run to peak power, always assuming that peak power is made at the same revs that is!

I suspect there's a little influence from the marketing department on these figures as well ;)

Mark

[AR]

Is all theoretical:

http://www.nsxprime.com/forums/showthread.php?t=94772

Cheers,

AR