long distance highway cruiser question

[angeno]

Hi All & Happy New Year/Decade!

After having the privilege of owning several beautiful examples of the breed, all manual trans NSX's, I'm thinking of getting back up on the horse (VTech horse that is). So far, I've owned a '91, '92, 94 & '99. Here's the thing. Taking nothing away from the targa models, as far as solidity, I think I prefer the fixed roof pre-'95 cars. Just my opinion of course. Primarily, the new car will be a thrice-yearly cross-country driver going between the East and West coast. And for this reason, I am perhaps a bit more sensitive to highway dynamics than the average person. For me, the lower the rpm in top gear, the better. This brings me to the crux of my question. To the knowledge of anyone in the community, does an option exist to switch out 5th gear for a taller overdrive ratio? Ideally, I'd like to be at ~2,000 rpm in top gear at 60 mph. I understand there would necessarily be a rather large step from 4th to 5th, but for my purposes that's not really a significant problem. I realize that if I select for a post '97 6 speed I might buy myself a few hundred rpm lower at given highway speeds. But if there's a straightforward way to simply switch out 5th gear in an older version, I think that's the way I'd prefer to go. Thanks so much for any help you folks can provide.

 

[Honcho]

All overdrive (5th) gears on the 5-speeds are the same ratio (0.771) JDM and US, so unfortunately there is no option for you. I'm not sure if the 6-speed 6th gear (0.717) will swap with a 5-speed 5th gear and even if it does, is it really worth the relatively small rpm drop?

If you're really looking for a nice highway cruiser, my recommendation would be to go with the 4-speed automatic hardtop coupe. It has taller gears (4th is a highway-friendly 0.684) and you can pick up a nice condition car at a price discount compared to the manual. Plus, you can use the sport shift mode if you want a spirited drive.

 

[angeno]

I appreciate the input, thank you. :smile:

 

[shawn110975]

and its VTEC not Vtech thats those cheap wireless home phones,, or the kids fake play laptops,, LOL,, good for you get another NSX and have those girls lookin!!

 

[CDX_NSX]

My solution was to swap a 6-speed tranny into my '93 coupé.

 

[Honcho]

That was my dream too (with NSX-R mainshaft and 4.23), until Mrs. Honcho slapped the budget on me.

My solution was to swap a 6-speed tranny into my '93 coupé.

Update for Angeno:

Using my handy gear ratio excel program, it turns out the 6-speed is the lowest RPM on the highway, even compared to the 4-speed auto. It turns out the auto has a higher final drive than the manuals (4.428).

RPM @ 60 mph (using my rear tire diameter of 24.9 inches)

5-speed: 2536
4-speed: 2452
6-speed: 2358

I think this just confirms once again that the 6-speed is the best transmission for the NSX.

 

[tbromley]

My solution was to swap a 6-speed tranny into my '93 coupé.

How hard was that to do the swap? How expensive was that and did you do a diy thing on it or did a shop do the work? Would love to know more about this! Thanks for posting this CDX!

 

[CDX_NSX]

How hard was that to do the swap? How expensive was that and did you do a diy thing on it or did a shop do the work? Would love to know more about this! Thanks for posting this CDX!

Well, I had it done by a shop but the cost for me was basically that of the transmission itself. There wasn't really any additional labor involved as I did it during the time of my engine build and it was essentially a matter of either bolting my 5-speed back on or bolting on the 6-speed. The only additional cost for me was a new clutch.

For the most part, in addition to the cost of the transmission, you would need a lock-out switch (6th to Reverse lockout - I didn't need one because I have an AEM EMS which can do the job).

The 6-speed runs a single disk clutch, so if your clutch is still good and you want to continue running it, or if you prefer to run a dual disk clutch you will need to get a Type-R input shaft that will allow you to run a dual disk clutch. Otherwise, you can opt to purchase a single disk clutch.

The price of the transmission varies rather widely, but you should be able to get a new one for about $5k.

 

[tbromley]

Well, I had it done by a shop but the cost for me was basically that of the transmission itself. There wasn't really any additional labor involved as I did it during the time of my engine build and it was essentially a matter of either bolting my 5-speed back on or bolting on the 6-speed. The only additional cost for me was a new clutch.

For the most part, in addition to the cost of the transmission, you would need a lock-out switch (6th to Reverse lockout - I didn't need one because I have an AEM EMS which can do the job).
The 6-speed runs a single disk clutch, so if your clutch is still good and you want to continue running it, or if you prefer to run a dual disk clutch you will need to get a Type-R input shaft that will allow you to run a dual disk clutch. Otherwise, you can opt to purchase a single disk clutch. (Quote)


How do you like the way it operates with the single disk clutch. That's of course what I have as I just replaced that. That's also when I should have done the tranny, if I was going to do anything like this. It would be expensive to do it now. The tranny is not cheap either. That's a lot to invest in the car unless your tranny was giving you trouble. Were your syncros going bad in the old tranny?

 

[4cruizn]

I do +/- 75% highway miles, and a cross country adventure at least a couple of times a year, so I find this thread interesting as well since I'm currently looking into my NSX purchase. I have a 1994 Legend 6-speed. I was curious how the gear ratios stacked up against the NSX 6MT and the Legend shows at .521 in 6th.

http://www.hondanews.com/categories/728/releases/3013

Ideally, I'd like to be at ~2,000 rpm in top gear at 60 mph.

That also made me curious, so I took a picture on my way home from the office today and mine sits right at around 1,900 RPM at 60 mph in 6th. Quite a change from my old rev-happy 3rd gen Prelude. I can routinely get better fuel economy than the 26 mpg highway rating on the window sticker.

Will keep an eye on where this discussion goes. I think the NSX 6MT will be out of my budget for awhile either way but that's certainly what I'd like to end up with eventually.

 

[docjohn]

If driven at or near the speed limit you can routinely get 26-28 mpg which is great for an old sportscar.Imo if you are only looking to save a few hundred revs modding the ring and pinion/gears ect is only one way,the other cheaper way is to put larger diameter tires on the car up to the max 5% stagger so as not to mess with tcs.But my best advice is to modify you,just live with whatever nsx you decide to buy,make a cross country trip and see if its as painful as you suppose it to be.

 

[CDX_NSX]

How do you like the way it operates with the single disk clutch. That's of course what I have as I just replaced that. That's also when I should have done the tranny, if I was going to do anything like this. It would be expensive to do it now. The tranny is not cheap either. That's a lot to invest in the car unless your tranny was giving you trouble. Were your syncros going bad in the old tranny?

I'll be honest and tell you that I couldn't tell the difference between the dual and single disk clutches as my car was down for 2 1/2 years between the removal of my old 5-speed transmission and the time I brought it home upon the completion of the project.

My 5-speed tranny was/is perfectly fine. One reason that I went with the 6-speed was that having driven only 6-speeds, the 5-speed transmission was messing me up because I kept wanting to shift to 6th. The other was that I wanted the taller 6th for cruising. The bonus for me was that the 6-speed's lower gears are close to those of the 5-speed short gears; two birds, one stone.

 

[sca037]

the other cheaper way is to put larger diameter tires on the car up to the max 5% stagger so as not to mess with tcs.

This was my first thought as well, get a second pair of rear wheels and mount larger diameter tires on them.
Of course, staying within the 5% offset for ABS/TCS reasons is prudent....so that will only yield you a 100 rpm drop or so (and a corresponding change in speedometer reading, since it's driven off the rear).

But my best advice is to modify you, just live with whatever nsx you decide to buy,make a cross country trip and see if its as painful as you suppose it to be.

Truly the best advice I think :wink:

Brian

 

[goldNSX]

And for this reason, I am perhaps a bit more sensitive to highway dynamics than the average person.

I still don't get get point why you want to have 2000 rpm at 60? Is it noise, is it mpg, anything else? As for the noise, the NSX is not a quiet car. Is it for mpg you won't gain much.

BTW I've just bought a ultrarare Insight, year 2000, as a pure cruiser, at 70 mph it is around 2000 rpm in fifth and I got home with 70 mpg and this was the first drive with the car, low tire-pressure, winter-tires and non-optimal battery as I've found out afterwards. And the project with this car didn't start yet. Sorry prime but I delocate my mind into electronics in the near future. No more projects on the NSX. :wink:

 

[Jetpilot3]

Wowzers! Did anyone else notice the 407,871 miles on that Acura Legend!!!

Impressive.:smile:

 

[Ben]

Wowzers! Did anyone else notice the 407,871 miles on that Acura Legend!!!

Impressive.:smile:

Heh, he's famous among the Legend guys. I'm sure he can tell it better, but believe it or not, the Legend in the pic is original engine, original head gasket, original transmission, and original clutch.

I've seen the car many times in person, and it looks cleaner than many 100K mile cars. I've also had the good fortune of driving it when it the mileage was still in the 300Ks, and it felt better than many 100K mile cars. :smile:

Crazy thing is that he just crossed 400K about 2 months ago, and has already put another 7K since then!!

 

[angeno]

I still don't get get point why you want to have 2000 rpm at 60? Is it noise, is it mpg, anything else? As for the noise, the NSX is not a quiet car. Is it for mpg you won't gain much.

For my part, it's neither about too much noise or not enough mpg. But instead there's a relative sense of comfort that comes from having a car cruise on the highway at a lower rpm. When you're carving corners or dicing in and out of traffic in your gen 1 5 speed NSX, this is a non-issue. For those of us, however, who occasionally use the car to cross whole states at a time, rpm at highway speed becomes a factor. Having had the distinct privilege of owning a 1st gen 5 speed car, and later, a 2nd gen 6 speed, I can verify that at 75 mph that extra gear does indeed make a difference. The reason I started this thread in the first place though was that I was hoping to find a less expensive solution than dropping an entire 6 speed transmission into the space previously occupied by a perfectly functional 5 speed. Based on the sensible commentary offered by you folks, it doesn't sound like this is a possibility though, unfortunately.