OEM US 5sp vs JDM 5sp short gears

[UnhuZ]

Hi,

My NSX just stopped because of a clutch death... i can't get into 1st or R
with the car idling, only when it's off, and then i start the car, and when i
start to disengage the clutch to get it moving, it shudders like hell, so it's
better not to even try to drive it.

After reading some very helpful PDF (http://scienceofspeed.com/products/drivetrain_performance_products/NSX/NSX_gear_ratios.pdf) in SOS website, i know i have:

5-spd (Japan short gears / standard final drive)
final drive . . . 1st . . . 2nd . . . 3rd . . . 4th . . . 5th
4.061:1 . . . 3.071 . 1.952 . . 1.400 . .1.033 . . 0.771
3000rpm . . . . 18 . . . 28 . . . . 39 . . . . 53 . . . . 71
8000rpm . . . . 47 . . . 75 . . . .104 . . . 141 . . . . 189


and US NSX have (and on online parts sites):

5-spd (standard gears / standard final drive)
final drive . . . 1st . . . 2nd . . . 3rd . . . 4th . . . 5th
4.062:1 . . . 3.071 . 1.727 . . 1.230 . .0.967 . . 0.771
3000rpm . . . . 18 . . . 32 . . . . 44 . . . . 56 . . . . 71
8000rpm . . . . 47 . . . 84 . . . . 118 . . . 151 . . . 189

as you can see, the 2nd, 3rd and 4th are different, so
with this, my question is:

If i open my transmission to look for damages/worn parts, and
refresh some parts, will everything be the same BUT the actual gears ??

looking at parts diagrams i see lot's of things that make me think if it
there isn't more into it than just the gears:

- bearings
- synchros
- washers
- rings
- fork hardware

and i assume that general o-rings and seals must be the same.

As i HAVE to open up to check everything, i will take advantage of the
time and labour to replace o-rings, seals, bearings, etc to new condition.

Can someone help me out? (Kaz ;))

Thanks in advance,
Nuno


PS - for the clutch, i'm deciding between SOS dual Carbon or SOS sport 400

[goldnsx]

Simply change the gears 2, 3 and 4 and you have JDM. Are you sure you have the long gears right now? With the long ones 2nd ends at around 130 km/h red-line, depending on the rear tire size. So YES, everything is the same BUT the actual gears. In Europe, 1993/4 or so the NSX's came with the JDM gears from the factory. Depending on the km on your gearbox some parts are worth replacing but you'll only know when you open it up. Bearings are good for 500k km in the NSX gearbox EXCEPT for one: the countershaft bearing and it's snapring. Change them FOR SURE. If you change the differential bearings you've more work to be done with adjusting the torque. If they're good I'd leave them as is. Synchros and fork hardware are difficult to judge with the tranny not open. The SM gives exactly measures and tolerances. If you have heavy shudder check the engine mountings too. They've been damaged or adding to the shudder. Good luck. Now you owe us some pics of the install. :)

[UnhuZ]

Hi Thomas,

thanks, but i don't want the longer 2,3 and 4...i have the JDM short gears (my car came like this from factory, and i want to keep them.

The thing is that it's cheaper to buy parts from US, and i need to be sure that every thing i need to change, except actual gears, it's
compatible, so i can buy from US.

SOS already told me the wareable parts (syncros, bearings, etc) are compatible across all years.

And yes, i'll take photos, but won't be me doing it, as i don't know how to do it, and i don't have the proper tools.

Thanks,
Nuno

[NSXGB]

Can't you take your transmission number to your local Honda dealership and ask them for a quote on the parts you require, then order that list from the US?

[Kaz-kzukNA1]

Hi, Nuno.

Initially, I couldn’t understand exactly what you wanted to know and also since there was no information about your NSX, it was almost impossible to advise anything including the point regarding the CL.

Like goldnsx, I also thought you were asking about the short gear ratio conversion.

For the clarification, yes, your assumption is correct that these parts are interchangeable between the short and the long ratio gbox apart from the gears.


However, you need to be bit careful with the wording ‘gears’.


The 1st, 2nd and Reverse Main gears are built-in to the mainshaft itself so any damages to these gears require new mainshaft.
(The reason why you need the new mainshaft for the short gear conversion.)

On a very-very early model gbox, the 2nd gear thickness on the mainshaft was slightly thinner than the latest design mainshaft that there was a single washer used between the 2nd and 3rd main gears.
If you order the mainshaft now, it will be the later spec one so you don’t use this washer on assembly.
Also, new mainshaft means you must select the correct thickness shim for the clearance.

Personally, I would replace all ball bearings (not the needle ones), not only the countershaft one but also the one at the both ends of the mainshaft (inc. the one at the CL case side).
If there is obvious damages or wear on each gears, it's easy to make decision on whether to replace it or not but it is hard to distinguish the evenly worn one unless you compare it with a new parts. Because of this, you may want to replace some of the gears any way if you covered enough mileage or especially if you track your NSX and use specific gear(s) for a long period.
There is a magnet piece near the oil pump drive gear so look for any big particles (I hope not....).

If you are looking for the acceleration improvement, then now is the time to modify the final ratio.
Final drive gear is built-in to the countershaft and the final driven gear is on the DF so requires replacing the countershaft. Again, requires the selection of correct shim and depending on the spec of final ratio and EPS controller version, you need to be bit careful triggering the EPS warning light.
Increasing the locking torque of OEM DF or even going for the aftermarket one is another good modification but as goldnsx mentioned, you need to spend some time opening and replacing the multiple plates and discs. You can’t even open the DF assy without the SST and I don’t know whether the SST is still available or not.

Sounded like you used your CL to the level where the torsion spring on the friction disc rusted and jammed somewhere inside the CL basket.
So, I guess you covered fair amount of mileage with your CL.
If that is the case, then I would replace the release bearing guide (MUST), release fork and even the spring and the hanger. Please invest in the good quality grease. Very important for the CL feeling. Honda Urea grease is very expensive (at least in Japan) but very good product.

For the selection of the CL, it all depends on the spec of your NSX, driving environment and purpose.
OEM one is probably the best all-rounder.
Light pedal feeling yet strong enough friction even for slight increase in engine power such as by the use of aftermarket header.
Easy to engage and very quiet even in the traffic.
Strictly speaking, you should replace all components as a set but if you act early enough (pedal started to feel heavier), you could live with by replacing just the two friction discs for the first CL service. On the second occasion, just replace all CL kit as a set.
However, it doesn’t like frequent high rpm quick engagement (i.e. without any slipping, ends up with juddery feeling) and due to its high friction coefficient material, it can chew into the flywheel surface as well.

The metal disc CL is almost the opposite direction.
It loves to be engaged quickly and doesn’t like being slipped (will cause juddery feeling) so if you have lightweight flywheel, you may find yourself busy dealing with the CL in the traffic. Depending on the design, it tends to make specific chattering noise (though I quite like it) and as mentioned above, it loves to be or it will bite like on/off engagement.
If you have modified the engine hardware, then you may have not much option but to go for the metal CL.

OEM CL + aftermarket flywheel is another good option.
If you are using OEM twin plates CL, then you are going to waste part of your money for getting the new OEM CL set and installing the aftermarket flywheel unless you are just replacing the two friction discs because Honda doesn’t sell the flywheel separately.
It won’t be as responsive as some of the aftermarket CL set (CL + flywheel kit) because the inertia of OEM set is fairly high but still, you can improve the response by reducing the inertia of flywheel.

I’ll be replacing my CL in the near future and my current choice is OEM CL + aftermarket flywheel.


Hope I understood at least part of your question......

Kaz

[markc]

Hi,

My NSX just stopped because of a clutch death...

Hi Nuno, sounds like you just have a clutch failure? If so there's no need to open up or monkey around with the gearbox itself.

Mark

[UnhuZ]

Hi,


Hi, Nuno.

Initially, I couldn’t understand exactly what you wanted to know and also since there was no information about your NSX, it was almost impossible to advise anything including the point regarding the CL.

Like goldnsx, I also thought you were asking about the short gear ratio conversion.

For the clarification, yes, your assumption is correct that these parts are interchangeable between the short and the long ratio gbox apart from the gears.
First of all, thanks for your insight...i really need your help on this.

to clear the matter, I don't want to convert to short ratios... my car came with the short JDM transmission from factory
(1st and 5th are the same as earlier Euro and US, and 2nd, 3rd and 4th are shorter)

The reason to all this, is that i will remove the transmission (and engine in fact) to do a major maintenance and clutch install, and
while i have everything off the car, i thought that it would be best to open up the transmission and replace any parts that show
ware, so the transmission become as new as i can get it (within financial reason)


Personally, I would replace all ball bearings (not the needle ones), not only the countershaft one but also the one at the both ends of the mainshaft (inc. the one at the CL case side).
If there is obvious damages or wear on each gears, it's easy to make decision on whether to replace it or not but it is hard to distinguish the evenly worn one unless you compare it with a new parts. Because of this, you may want to replace some of the gears any way if you covered enough mileage or especially if you track your NSX and use specific gear(s) for a long period.
There is a magnet piece near the oil pump drive gear so look for any big particles (I hope not....).

so i don't miss anything, in the next posts i will include pictures of my Excel parts file (built from online diagrams and parts list)
with the parts i think i have to buy (in orange) and the ones i need your help to decide (yellow)
(I post them in new posts because of the 4 images limit here, which i don't quite understand why, so they are all together.)

My clutch is the original one, that came from factory, and have now 220.000kms, So my transmission also have 220.000kms.

about gear usage, i do a lot of mountain roads, like touges in japan ;), and also a lot of very high speed runs, 250+ (km/h)
this must make the usage about the same in all gears.



If you are looking for the acceleration improvement, then now is the time to modify the final ratio.
Final drive gear is built-in to the countershaft and the final driven gear is on the DF so requires replacing the countershaft. Again, requires the selection of correct shim and depending on the spec of final ratio and EPS controller version, you need to be bit careful triggering the EPS warning light.
You are scaring me with that EPS reference. Can you specify exactly which "shim" you refer to in the images i'll post below?


Increasing the locking torque of OEM DF or even going for the aftermarket one is another good modification but as goldnsx mentioned, you need to spend some time opening and replacing the multiple plates and discs. You can’t even open the DF assy without the SST and I don’t know whether the SST is still available or not.
and now i'm lost.... i don't intend to mess with the DF, and will only do it, by replacing with a new one (thinking of what Adnan been saying about Quaife)


Sounded like you used your CL to the level where the torsion spring on the friction disc rusted and jammed somewhere inside the CL basket.
So, I guess you covered fair amount of mileage with your CL.
If that is the case, then I would replace the release bearing guide (MUST), release fork and even the spring and the hanger. Please invest in the good quality grease. Very important for the CL feeling. Honda Urea grease is very expensive (at least in Japan) but very good product.
ok... i think i highlighted all those parts in my diagrams. and i already have a Urea grease pot, brand new ;) (that green goo right?)


For the selection of the CL, it all depends on the spec of your NSX, driving environment and purpose.
OEM one is probably the best all-rounder.
Light pedal feeling yet strong enough friction even for slight increase in engine power such as by the use of aftermarket header.
Easy to engage and very quiet even in the traffic.
Strictly speaking, you should replace all components as a set but if you act early enough (pedal started to feel heavier), you could live with by replacing just the two friction discs for the first CL service. On the second occasion, just replace all CL kit as a set.
However, it doesn’t like frequent high rpm quick engagement (i.e. without any slipping, ends up with juddery feeling) and due to its high friction coefficient material, it can chew into the flywheel surface as well.
i'm deciding on one of 2 SOS sets, the sport 400 or the twin Carbon one... i intend to go turbo down the road, and as i have to replace it now,
i think i better choose a good strong one now.


The metal disc CL is almost the opposite direction.
It loves to be engaged quickly and doesn’t like being slipped (will cause juddery feeling) so if you have lightweight flywheel, you may find yourself busy dealing with the CL in the traffic. Depending on the design, it tends to make specific chattering noise (though I quite like it) and as mentioned above, it loves to be or it will bite like on/off engagement.
If you have modified the engine hardware, then you may have not much option but to go for the metal CL.
i'm lost again Kaz.... don't understand what you are trying to say.


I’ll be replacing my CL in the near future and my current choice is OEM CL + aftermarket flywheel.
why won't you go with a aftermarket set, like Exedy, or even the SOS ones....

The Exedy is the best, but a lot hard to daily drive, but the SOS ones are like OEM, but can take a lot more power... and if you don't have
a lot more power, i think they will last longer for the same usage, no?



Hope I understood at least part of your question......
i think i made my doubts more clear now...

Thanks a lot Kaz....can you please check the posts i will make after this one, so you can check and tell me all i need to buy ??



Can't you take your transmission number to your local Honda dealership and ask them for a quote on the parts you require, then order that list from the US?
I can do that, although the parts guys here are a bit clueless


Hi Nuno, sounds like you just have a clutch failure? If so there's no need to open up or monkey around with the gearbox itself.
Well... the clutch didn't had a sudden death, it was giving slight signs of "replace me" for about the last 30.000kms... and although i've always shifted with care, ware is in there due to the high mileage of the car.

Thanks,
Nuno

[UnhuZ]

Hi,

Kaz, as i said above, here are the 3 posts showing all transmission parts diagrams from the online catalog.

I highlighted in Orange what i intend to buy for sure, and in Yellow what i need you to tell me to buy or not.
(parts in green mean i already have them (clutch bearings and flywheel bolts)

the Clutch and DF diagrams, i didn't highlight anything because i will not mess with OEM DF and i will buy an aftermarket clutch set



http://www.nsxprime.com/photopost/data/1438/thumbs/0115.jpg (http://www.nsxprime.com/photopost/projects-3a-mechanical-huge-maintenance/p49284-0115.html)


http://www.nsxprime.com/photopost/data/1438/thumbs/0217.jpg (http://www.nsxprime.com/photopost/projects-3a-mechanical-huge-maintenance/p49285-0217.html)


http://www.nsxprime.com/photopost/data/1438/thumbs/0310.jpg (http://www.nsxprime.com/photopost/projects-3a-mechanical-huge-maintenance/p49286-0310.html)


http://www.nsxprime.com/photopost/data/1438/thumbs/0410.jpg (http://www.nsxprime.com/photopost/projects-3a-mechanical-huge-maintenance/p49287-0410.html)

[UnhuZ]

http://www.nsxprime.com/photopost/data/1438/thumbs/056.jpg (http://www.nsxprime.com/photopost/projects-3a-mechanical-huge-maintenance/p49288-056.html)


http://www.nsxprime.com/photopost/data/1438/thumbs/067.jpg (http://www.nsxprime.com/photopost/projects-3a-mechanical-huge-maintenance/p49289-067.html)


http://www.nsxprime.com/photopost/data/1438/thumbs/071.jpg (http://www.nsxprime.com/photopost/projects-3a-mechanical-huge-maintenance/p49290-071.html)


http://www.nsxprime.com/photopost/data/1438/thumbs/084.jpg (http://www.nsxprime.com/photopost/projects-3a-mechanical-huge-maintenance/p49291-084.html)

[UnhuZ]

http://www.nsxprime.com/photopost/data/1438/thumbs/091.jpg (http://www.nsxprime.com/photopost/projects-3a-mechanical-huge-maintenance/p49292-091.html)



http://www.nsxprime.com/photopost/data/1438/thumbs/105.jpg (http://www.nsxprime.com/photopost/projects-3a-mechanical-huge-maintenance/p49293-105.html)

well... i think that is it.

If you think i should buy something that it's not here, please tell me so i can add it to my list.

Thanks,
Nuno

[goldnsx]

220'000 km on the first clutch, I think we have a record! With this mileage you may hear some noise/whining from the gears or final drive (pretty sure). As Kaz mentioned a 4.23 would be an option to think about. The stiffer diff (NSX-R) also. Other final drives/diff settings are quite pricey but will work for some people. What I don't understand: why don't you give yourself a little more time and order the parts AFTER you had a look in the tranny? I for myself also wait until my clutch to fail and already have a spare clutch kit but will first have a diagnosis on what to replace. But now as I hear that you were able to squeeze 220'000 km out of the first one I think I've to postpone it a little bit. :)

[UnhuZ]

and Thomas, it could have lasted longer, but the springs on the pressure plate died.... i'm sure that the discs still have meat on them, as it never slipped.

About the noises/whining... ZERO... no noises from the transmission.

About ordering parts before, you are right, but i want to have all the little stuff... so if i don't need any gear or shaft, i'm ready to go... if i need anything else,
it will be a lower volume and a lot less probable waiting period then ;)

[goldnsx]

No noise = no wear of the gears. I'd leave them as is and follow Kaz's recommendations. Main bearings and seals. Not sure about the shift forks. Hard to judge as long as it doesn't jump out of any gear. Interesting to see what you'll find in the gearbox.

[Kaz-kzukNA1]

well... i think that is it.

If you think i should buy something that it's not here, please tell me so i can add it to my list.

Thanks,
Nuno
Can’t see anything (neither attachment nor link) in your all three posts that meant to have some sort of Excel file based on your post #7.
Running Firefox in Safe mode didn’t make any differences but I know there seem to be a certain issue related to attachment feature running Firefox with latest vBulletin software so looks like I need to try using different browser.
Will try it later.

Kaz

[goldnsx]

Can’t see anything (neither attachment nor link) in your all three posts+1 same for me

[UnhuZ]

weird... they are simply jpg images i hosted on Prime :(

i use chrome and they show fine on my other computer !!

either way, here is a link to my album on Prime that i created only for these images:

http://www.nsxprime.com/photopost/g1438-projects-3a-mechanical-huge-maintenance.html

[NSXGB]

I can see them fine. Using Safari browser.

[britlude]

right click on the broken pic icons and open in new window they come up in the new window.. looks like prime doesn't allow direct links to their server based pics?

hang on, think i've worked it out, gotta use the url links on each page.... i can see it on google chrome...


give me a moment... might work....

http://www.nsxprime.com/photopost/data/1438/0115.jpg (http://www.nsxprime.com/photopost/projects-3a-mechanical-huge-maintenance/p49284-0115.html)

http://www.nsxprime.com/photopost/data/1438/0217.jpg (http://www.nsxprime.com/photopost/projects-3a-mechanical-huge-maintenance/p49285-0217.html)

http://www.nsxprime.com/photopost/data/1438/0310.jpg (http://www.nsxprime.com/photopost/projects-3a-mechanical-huge-maintenance/p49286-0310.html)

http://www.nsxprime.com/photopost/data/1438/0410.jpg (http://www.nsxprime.com/photopost/projects-3a-mechanical-huge-maintenance/p49287-0410.html)

[britlude]

next 4....

http://www.nsxprime.com/photopost/data/1438/056.jpg (http://www.nsxprime.com/photopost/projects-3a-mechanical-huge-maintenance/p49288-056.html)

http://www.nsxprime.com/photopost/data/1438/067.jpg (http://www.nsxprime.com/photopost/projects-3a-mechanical-huge-maintenance/p49289-067.html)

http://www.nsxprime.com/photopost/data/1438/071.jpg (http://www.nsxprime.com/photopost/projects-3a-mechanical-huge-maintenance/p49290-071.html)

http://www.nsxprime.com/photopost/data/1438/084.jpg (http://www.nsxprime.com/photopost/projects-3a-mechanical-huge-maintenance/p49291-084.html)

[britlude]

last 2....

http://www.nsxprime.com/photopost/data/1438/091.jpg (http://www.nsxprime.com/photopost/projects-3a-mechanical-huge-maintenance/p49292-091.html)

http://www.nsxprime.com/photopost/data/1438/medium/105.jpg (http://www.nsxprime.com/photopost/projects-3a-mechanical-huge-maintenance/p49293-105.html)


hope that helps! very odd... since i added these links, the original thumbs come up in UnHuZ's posts on page1!!!

[UnhuZ]

^ to get even more weird, i can see the pics on my original posts, but can't see yours....

[UnhuZ]

Kaz, if you can't see the images, you can give me your email and i'll send them over to you...

i appreciate your help.

Thanks,
Nuno

[britlude]

basically the pics are the parts lists for the manual gearbox...

see the bottom of the Lings part pages... (random manual nsx selected!)

http://www.lingshondaparts.com/honda_car_parts_block_selection_C30.php?mod_01=216 80

[UnhuZ]

^ yeap, but i have selections in the list with what i think i should replace (orange) and what i have doubts (yellow)

[Kaz-kzukNA1]

I’ll get back to you once I have extra free time.

At the moment, I have many high priority items including the two NSXs that I am working on and then there are more than 10 owners ahead of you with email support for EPS, brake, parts, etc.


Kaz

[UnhuZ]

No problem Kaz.... your timing is my timing....

i only wish that i'd live in UK so i can give you my NSX to work on ;)

Thanks for your help,
Nuno

[Kaz-kzukNA1]

The yellow parts that were included in your diagram but not mentioned below depend on the existing condition, inspection result, selection of other parts, etc and these have to be decided by your engineer.
There were items that can be re-used if they looked fine or within the measured tolerance window.


In my view, gbox service tends to show larger difference in the end result than the engine service depending on who worked on it even using exactly the same procedure, tools, parts, etc.


So, it comes down to just these;

https://lh4.googleusercontent.com/-ArqSiSVnRaQ/Uhoacloz8PI/AAAAAAAALNc/4aDpQFH4J9o/s640/0217.jpg

For my service, #1 & 4 are part of MUST items to be replaced but please check the compatibility if you are going to use the aftermarket CL.

Kaz

[UnhuZ]

Thanks Kaz.... i was already thinking about buying the fork and the bearing guide anyways.

Thanks once again for your help.

Nuno

[Kaz-kzukNA1]

It's green marked in the above diagram so bit too late for you but next time if you are or anyone buying the release bearing #3, just buy it from Honda UK.
So much cheaper than US or Japan price.

Kaz