Questions about 1g NSX 5MT and 6MT transmissions
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B*a*n*n*e*d
Joined: Mar 2003
Posts: 9,783
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From: Greenville, South Carolina
Questions about 1g NSX 5MT and 6MT transmissions
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/par...713&series=E30
https://www.hubauer-shop.de/de/nadel...221224713.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
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
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/par...713&series=E30
https://www.hubauer-shop.de/de/nadel...221224713.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
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:
NSX 91-94 3.071=43/14 1.727=38/22 1.23 =32/26 ??? 0.966=29/30 0.771=27/35 ----------- 4.062=65/16 NSX 91-94 Type R 3.071=43/14 1.952=41/21 1.400=35/25 1.033=31/30 0.771=27/35 ----------- 4.235=72/17 NSX 95-96 3.071=43/14 1.800=36/20 1.23 =32/26 ??? 0.966=29/30 0.771=27/35 ------------ 4.235=72/17 NSX 6speed, 1997+ 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
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