Short Gears and R&P 4.23

[mackash]

Goldnsx-
Any updated on your car with the gear swap?

 

[goldNSX]

Goldnsx-
Any updated on your car with the gear swap?

My mechanic is working on the shorties and final drive these days. I'll get my car on Friday or Saturday and will be able to give you a short feedback. I'll keep you informed with a detailed analysis a few weeks later...
Greetings,
Thomas

 

[mystican]

Good thread on the short gears and R/P.

I was wondering how much it costs to convert over to short gears and R/P 4.23...I have a 1991

 

[goldNSX]

Hi

The shorties and final drive 4.23 are installed since yesterday. As some of you like to get a feedback here it is. Since I didn't have the opportunity to do a flying lap on the Schwägalp (reference) please have in mind that these infos here are still uncomplete. Further analysis will be done the next 2 weeks.
I took her home (2 hours) and had the opportunity to drive at different speeds hill up and down plus a short highway.
I got into the car after 2 weeks not driving her so it was a little bit unconsious who she behaved before. The first meters I didn't felt any difference. The alignment was done too so I first had to get to her new driving behaviour (lighter steering). After some 100 meters I felt that I don't have to wait an extra second while shifting from 1st to 2nd. After some kilometers I still had to learn the new shifting points. But after I while I recognized what I have done. It's very nicely if not perfectly spaced. No headbanging while shifting from 1st to 2nd, no extra second to wait for the power. She definitly feels lighter on her feet. Doing a 0-60 mph brought a smile on my face the first time. Overtaking someone starting at 40 mph is really some kind of a different world. No bogging, no waiting for torque or VTEC. I can overtake someone in situations now where my passenger started to pray before. Just get on the throttle and it *zings*, very impressive. I can't tell for sure if the final drive was worth it. The shorties do a lot here. But my mind tells me that the final drive is the dot on the i.

I can give you some more infos in about 2 weeks.
Thanks for all who helped me and the excellent infos provided!

Greetings,
Thomas

 

[ATERPAK]

Your last sentence about dotting the i was a perfect analogy for this setup. I think you'll like it even better as you get use to it and learn where to use your new found flexibility. Enjoy!

:biggrin:

 

[gheba_nsx]

Finally it is doine! Compliments Thomas! I'll see the car soon!

 

[NetViper]

Let me give you my initial impressions of the shorties and 4.55. I think they are almost too short. I think the 4.23 might be a nicer way to go. The lag between 1-2 is certainly gone though! I personally think the 6-speed is the way to go.

 

[goldNSX]

...I personally think the 6-speed is the way to go.

but the most expensive one too. I canceled the 6-speed due to the very high costs compared to the small gains. IMO for a 91 with a (new) clutch with 15'000 miles on it you can't gain with a 6-speed in the speed-range of 0-100 mph where I drive 99.9 %. Within that speed-range I don't feel any gap between 3rd, 4th and 5th even if I shift to 4th or 5th far below the rev-limiter. Remember that you have to install the R&P 4.23 in the 6-speed too and to change the clutch to gain the same results which nearly doubles the costs overall.
On a race track or the German Autobahn things may looks different but for a weekend-driver and sometimes fun-racer like me it's the best setup for the money I think.

I'll tell you soon after my flying lap over the Schwägalp this weekend.

Greetings,
Thomas

 

[goldNSX]

or maybe the GIKEN 4.44 is another way to go than the 4.55, see http://www.scienceofspeed.com/products/drivetrain_performance_products/NSX/OS-Giken/
Question to Chris of SOS: Is the GIKEN Final Drive without the LSD available? What would be the price?

Greetings,
Thomas

 

[nsxtasy]

I was wondering how much it costs to convert over to short gears and R/P 4.23...I have a 1991

You can check the parts cost on the Science of Speed website. It takes 8-12 hours of labor to open up the transmission, so it makes sense to try to combine it with any other transmission work you're contemplating (clutch replacement, hub selector/synchro replacement, snap ring fix, etc).

Keep in mind that for track use, the stock gears on the five-speed may be better than the short gears, since the stock gears are quicker at the 70-110 mph speeds most common at the track. The R&P change tends to make little difference on the track (it may help slightly on some tracks, and hurt slightly on others).

 

[goldNSX]

Sorry, I wasn't able to do my flying lap over the Schwägalp since the install.
But I have some other comments and questions so far.
The flexibility and power of the shorties and final drive 4.23 are absolutly great. It's really wonderful for street pleasure.
But now I come to a point which I was worring about before: I have a serious traction problem even driving a staight line. In 2nd and 3rd starting slowly to full throttle at 1500 rpm (that's what I call low end torquing ) TCS light comes up even in 3rd gear! She has the OEM Yokos on her feet with Eibach/Bilstein. Reving to the limiter in 2nd results often in a TCS-light until traction is better assuming that traction is bad. The roads are clear and dry.
So MY QUESTION: I think I'm getting those soft Eibach springs/Bilsteins out and move to the real Zanardi setup. Is this a good way to get more traction in the rear? I suspect that the initial Eibach spring rate is too soft and must wait until the weight is transferred to the rear. What else can I do to improve it?
Unfortunately the alignment was done but doesn't match my needs. In short: only toe was changed the rest was ok: Front from +(!) 3 mm to -1mm, rear from +12 (!) mm to +6 mm. The car now feels a little bit nervous driving a straight line and definitly feels unstable in turns with a great tendency of oversteering in corners under middle acceleration. Turning response is much better but stability exiting a corner is more worth/safe to me.
What can I do to get more traction under accelleration?

Greetings,
Thomas

 

[The Kid]

mine should be done soon as well...

 

[goldNSX]

The car now feels a little bit nervous driving a straight line and definitly feels unstable in turns with a great tendency of oversteering in corners under middle acceleration.

Sorry there's a mistake: I have UNDERsteering in turns (not oversteering) under middle accelleration.

 

[MJK]

Wow, that sounds like quite a difference in power delivery! The twitchiness/corning sounds like your alignment was messed up with the removal of the tranny to me. I think I would get that checked.

 

[goldNSX]

I have my new gearbox for about 4 weeks and can tell now a little bit more to those how have the swap in mind. I drove on the Schwägalp (hill up and down with a punch of 180 degrees curves) on friday.
IMO the shorties plus final drive 4.23 are perfect and transfer the NSX to a really different car, a real supercar.

That's why I love it (in this order):
- no gap between 1st and 2nd
- no bogging in 2nd in slow corners
- higher acceleration in all gears, especially 2nd and 3rd
- less (!) gearbox noises (compared to my old one with 50k)
- better behaviour in traffic jam as 2nd is much better usable as soon as you left 1st

(very small) negative points:
- As the revs are a little bit higher the engine 'breaks' a little bit more in 5th downhill, 6 gears with final drive 4.23 would be perfect but IMO too expensive to cancel out this point
- a small (noticable but negligable) gap between 4th and 5th
- 0.6 liters/ 100 km more fuel consumption (9.5 instead of 8.9), maybe I was a little bit more enthusiastic
- it's not a pure sunday driver car anymore

Resumé: I can't understand why Honda ever built the long gears. On a race track or the German Autobahn it might be reasonable.
The final drive is like the dot on the i. Not a breakthrough but very nice. But I would never do the final drive alone on a 91-94. It's quite expensive but I now have a fully rebuilt gearbox in my NSX.
It's like my NSX's rebirth. I would suggest this the best upgrade for a 91-94.

Thanks to all who supplied me with plenty of materials, graphs, data and their opinion. That's why I call this community the best in the world.

Greetings,
Thomas

 

[The Kid]

driving mine home tommorow night! shorties and 4.23 :biggrin:

 

[MvM]

It seems everyone seems to like the short gears.
But what are the differences for higher speeds, say, above 90 mph and further.

 

[nsxtasy]

It seems everyone seems to like the short gears.

Not everyone. I like the stock gears and stock R&P. I think they are better suited for track use. Most of the advantage of the short gears is in the 40-70 mph range, and they are a slight disadvantage at speeds above 70 mph, which is where most of the time on the racetrack is spent. Similarly, the R&P doesn't really change overall rates of acceleration at track speeds (when you are shifting gears), even though it changes the shift points (speeds at which you shift).

I think both mods are worthwhile if you take your car to the dragstrip (or if you are concerned about the "stoplight grand prix"), since they benefit acceleration at lower speeds.

what are the differences for higher speeds, say, above 90 mph and further.

90-150 mph acceleration:
Stock '91: 27.62 seconds
Stock '91 with short gears and 4.235 R&P: 30.14 seconds

Figures courtesy of Bob Butler.

 

[MvM]

Nsxtasy,

Thanks for the info. I must have the data from Bob Butler somewhere but don't have it at hand. I just checked the numbers in the FAQ though. They list the 0-140 mph for the stock 5-speed as 28.9 seconds versus 30.04 for short gears & 4.235 final. So the advantage really is only part below 100 mph.
And since I do tend to travel quite often at those speeds (if even only for a short while), I think this is not something for me.

 

[NetViper]

Personally, I liked the OEM gears for a track where you don't have a lot of slow (ish) turns.

The biggest advantage is that the 1-2 shift lag is gone. I probably would not spend the money for shorties and 4.23 if it was my car, but it does make it more fun to blast around on the street.

I think the 6-speed is the best of both worlds.

 

[docjohn]

I think a side benefit of the shorter final drive if you track the car is to distribute the wear and tear on the tranny; street and track.What I mean is that on the street you will be hard on 1-3 gear synchros ect,at most tracks I run at I'm tough on 3-5 gear shifts thus somewhat distributing the pain,so to speak.

 

[nsxtasy]

I think a side benefit of the shorter final drive if you track the car is to distribute the wear and tear on the tranny; street and track.What I mean is that on the street you will be hard on 1-3 gear synchros ect,at most tracks I run at I'm tough on 3-5 gear shifts thus somewhat distributing the pain,so to speak.

I don't know if that's true, but if it is, it is primarily due to the fact that you're driving on the track, rather than to differences between the two gear set-ups. (Not that any of us needs any justification for track driving... )

 

[Andrie Hartanto]

I personally hate the stock gear and R&P.

My car was stock gearing. When I drove George Wang's car with short gear and 4.23, I thought it was mild improvement. Then I drove a 6 speed, which I thought it is an even better improvement. Then I drove a 6 speed with 4.55, and I thought this think is awesome! I also drove Kenji's car with stock gear and 4.55, and I thought it was a better deal than short gear and 4.23.

The past Friday I drove the same car that had the 6 speed with 4.55, but this time no 4.55 instead a stock 4.062. I thought it really make the car feel sluggish and not responsive. Wish Comptech still make the 4.55 so we didn't have to move the gear to the race car.

 

[goldNSX]

My driving speeds are 99.9 % below 100 mph. I love to drive hills up and down (german: Bergrennen ). There are always some 180 degrees turns with speeds below 35 mph. Pictures of my favorite Schwägalp 'track' will follow this weekend. That's where the shorties and final drive transfer the car to a really different world. It's also very much fun to drive through a city as a little street racer who is interested in short sprints. So I conclude it's one of the best mods for street and hill racing, but on a race track things look different. I suggest that the long gears (plus 4.23) are perfect for track use as long as you don't have too much slow corners because the gearbox is nicely spaced between 2nd and 5th.

Greetings,
Thomas

 

[nsxtasy]

Then I drove a 6 speed, which I thought it is an even better improvement. Then I drove a 6 speed with 4.55, and I thought this think is awesome! I also drove Kenji's car with stock gear and 4.55, and I thought it was a better deal than short gear and 4.23.

The past Friday I drove the same car that had the 6 speed with 4.55, but this time no 4.55 instead a stock 4.062. I thought it really make the car feel sluggish and not responsive.

First gear in the six-speed is ever so slightly taller than first gear in the five-speed (which isn't changed by the short gears). So there is absolutely no advantage to the six-speed until you run out of first gear (i.e. below ~45 mph). Its advantage is only above 45 mph, where the gears from second on up are shorter and spaced closer together. Overall, I consider the six-speed an improvement over the five-speed.