As far as I can tell, there are 3 different 5speed transmissions. Below is what I estimate the gear teeth count to be. Please correct me if my estimations are off. I have 2-3 questions about the 1g NSX manual transmissions.
Question #1 - Is the C.D. (centre distance, the distance between the center axis of the mainshaft and the center axis of the countershaft) between the 5-speed and the 6-speed the same?
Question #2 - Are the countershaft spline sizes between the 5-speed trans and the 6-speed transmission the same?
If this is the case, then I believe that it is possible to use some of the 6-speed gears inside of the 5-speed trans by doing one of two things:
1) Using a combination of specifically sized DIN 988 shims along with a slightly modified needle bearing from a BMW transmission (BMW part number 23221224713)
https://www.realoem.com/bmw/enUS/pa...sg=15&diagId=23_0551&q=23221224713&series=E30
https://www.hubauer-shop.de/de/nadelkaefig-23221224713.html
2) Taking a 4th/5th collar and turning the OD of the 4th gear side down from 43mm OD to 42mm OD, and then using 4th gear needle bearing from the 6-speed trans.
23915-PR8-000 Collar, Distance (36X43X62.5) $82.13
91107-PR8-F01 BEARING, NEEDLE (42X47X26.5) $25.49
This would allow the following gear ratios in an OEM 5-speed transmission:
1st = 42/14 = 3.071
2nd = 38/22 = 1.727 (or 36/20 = 1.800)
3rd = 35/25 = 1.400 (JDM Type R)
4th = 36/32 = 1.125 (Modified 6-speed 4tH)
5th = 32/35 = 0.914 (Modified 97-99 6-speed 5th)
Final = 65/16 = 4.0625
Edit - updating theoretical trans to include 1.800 second gear option
Question #1 - Is the C.D. (centre distance, the distance between the center axis of the mainshaft and the center axis of the countershaft) between the 5-speed and the 6-speed the same?
Question #2 - Are the countershaft spline sizes between the 5-speed trans and the 6-speed transmission the same?
If this is the case, then I believe that it is possible to use some of the 6-speed gears inside of the 5-speed trans by doing one of two things:
1) Using a combination of specifically sized DIN 988 shims along with a slightly modified needle bearing from a BMW transmission (BMW part number 23221224713)
https://www.realoem.com/bmw/enUS/pa...sg=15&diagId=23_0551&q=23221224713&series=E30
https://www.hubauer-shop.de/de/nadelkaefig-23221224713.html
2) Taking a 4th/5th collar and turning the OD of the 4th gear side down from 43mm OD to 42mm OD, and then using 4th gear needle bearing from the 6-speed trans.
23915-PR8-000 Collar, Distance (36X43X62.5) $82.13
91107-PR8-F01 BEARING, NEEDLE (42X47X26.5) $25.49
This would allow the following gear ratios in an OEM 5-speed transmission:
1st = 42/14 = 3.071
2nd = 38/22 = 1.727 (or 36/20 = 1.800)
3rd = 35/25 = 1.400 (JDM Type R)
4th = 36/32 = 1.125 (Modified 6-speed 4tH)
5th = 32/35 = 0.914 (Modified 97-99 6-speed 5th)
Final = 65/16 = 4.0625
Code:
[B]NSX 91-94[/B]
3.071=43/14
1.727=38/22
1.23 =32/26 ???
0.966=29/30
0.771=27/35
-----------
4.062=65/16
[B]NSX 91-94 Type R[/B]
3.071=43/14
1.952=41/21
1.400=35/25
1.033=31/30
0.771=27/35
-----------
4.235=72/17
[B]NSX 95-96[/B]
3.071=43/14
1.800=36/20
1.23 =32/26 ???
0.966=29/30
0.771=27/35
------------
4.235=72/17
[B]NSX 6speed, 1997+[/B]
3.066=46/15
1.956=45/23
1.428=40/28
1.125=36/32 ?
0.914=32/35
0.717=28/39
-----------
4.062=65/16
Edit - updating theoretical trans to include 1.800 second gear option
Last edited: