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Thread: Gbox 5 MT (short gears) - quantity of teeth, gearwheel diameter

  1. #1

    Default Gbox 5 MT (short gears) - quantity of teeth, gearwheel diameter

    I have in my 96' NSX 5MT Gbox US spec
    I bought in UK (as in the picture) 5MT Gbox EU Spec?

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    someone can give me : a diameter gearwheel, (or) quantity of teeth for the second, third gear (On -Mainshaft)– for “short gear”

    5 Gear :diameter gearwheel : inch 3,86 or 98,3mm quantity of teeth: 35
    4 Gear :diameter gearwheel : inch 3,50 or 89,2mm quantity of teeth: 31
    3 Gear :diameter gearwheel : inch 3,14 or 80mm quantity of teeth: 26
    2 Gear :diameter gearwheel : inch 2,63 or 67mm quantity of teeth: 22
    1 Gear :diameter gearwheel : inch 1,88 or 47mm quantity of teeth: 14

    Thanks for your help
    Last edited by ozon02; 26-02-2016 at 05:29 PM.

  2. #2
    Join Date
    Sep 2008
    Bucks, UK
    Blog Entries


    Don’t have all the time counting the gears so please refer to the above photos.
    1st and 5th gear ratios are the same between JDM (shorter ratio) and Acura 5MT.

    European models were equipped with the same ratio as JDM at later year.

    Basically, at the Main shaft side, the diameter of the gears on the JDM (shorter) spec is smaller than the Acura one.

    2nd main gear is directly machined on the Main shaft so you need to replace the shaft body itself, if you want the shorter ratio spec.
    I hope your European spec spare Main/Counter shafts/gears are the shorter spec.... Your photo was not easy to see even after enlarging it.

    If you remove the 3rd main gear or if you look at from the small gap behind the Reverse gear, you will notice how close the main 2nd gear is to the shaft body on the JDM spec (the distance marked in yellow).

    Quote Originally Posted by ozon02 View Post
    1 Gear :
    2 Gear :
    3 Gear :
    4 Gear :
    5 Gear :
    By the way, I hope these numbers you are using above as well as in your photo are not referring to the actual gear positions. They are at wrong position but probably you know about it.....

    Last edited by Kaz-kzukNA1; 25-02-2016 at 08:27 PM. Reason: english.... Link to the photo updated.

  3. #3
    Join Date
    Sep 2008
    Bucks, UK
    Blog Entries


    Found some free time so counted the gear teeth for you.

    If you counted the number of gear teeth correctly, looks like you bought the early European spec gears/shafts and thus, I’m afraid, it’s not the shorter ratio spec…

    #2 in your photo - 4th gear. JDM Main 4th: 30 teeth, you counted it as 31 that is the longer ratio spec.
    #3 in your photo – 3rd gear. JDM Main 3rd: 25 teeth, you counted it as 26 that is the longer ratio spec.


  4. #4


    Thanks Kaz,
    your pictures dispelled my doubts.It is US spec-Seller put me in confusion.
    From member "drmikey" I bought OS Giken LSD with 4,4 final ratio and on the occasion of disassembling transmission I wanted to shorten gears.
    Kaz what do You think about it ?
    It can still take this opportunity to mount the lightweight flywheel?

    As for the engine. I do not want make any changes.How do they do it willingly in USA (NSX Prime)

  5. #5
    Join Date
    Mar 2013


    Quote Originally Posted by ozon02 View Post
    As for the engine. I do not want make any changes.How do they do it willingly in USA (NSX Prime)
    That's why we all say, "ONLY IN AMERICA!!!"

    1992 My beloved Red/Black manual NA1.😎
    1992 Chevy Lumina apv Rockford Fosgate sound system demo van.🙉
    2003 Hartge Mini Cooper S (2 x UK & 1 x European sound quality finals winner) 🏆 

    "The NSX's greatest victory was to WIN the 1995 Le Mans 24hr GT2 Class"
    ..............and guess what, it was a RED one but of course.  

  6. #6


    i want to ask if Gbox J4E32000072 is EU spec "short gears"
    early Gbox EU spec for example J4A41001265 is also "short gears"

  7. #7


    After a long wait I received a copy of the Differential Inspection Tools 07MAJ-PR90100 ordered from my colleague

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    and checked preset torque

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    in Manual is Standard 59-137 Nm my is 101Nm- I am happy with result

    by the way I ordered 2 Differential Tools

  8. #8


    I would like to ask for help in translating from Japanese.
    My experience of using OS Giken LSD 1,5 with 4.4 Final Gear:
    Track use very very fun - getting out of the corner
    Road use - and here it is worse - parking, tight corners, metallic noise.
    I read the article by Mr. Toyoizumi from T3TEC and translated it through Google. I decided to ask Mr. Toyoizumi for directions on how to tune LSD according to his experience. I used photos from MotoIQ with an indication of which components I should change (to which kg for springs)

    Good morning
    I read your article about OS Giken LSD. I learned a lot. I have this set bought 10 years ago. On the track it gives a lot of fun but in the city it is noisy at tight corners, on public roads it is even a little dangerous. I would like to adjust it by referring to your experience and achieve a balance between urban driving and fun on the track with an emphasis on urban driving.
    1. Please tell which springs I should use
    18 kg or 28 kg or 38kg
    2.which the preload cone spring is 1,2 mm or 1,4 mm or 1,6 mm
    3. How many clutch discs should I deactivate?
    2 paar (remains 20 aktiv)

    , please give me a hint

    I received an answer:






    ... and I,m lost

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