Snap ring - why not all 91 in range??

[nis350]

After read the article regarding the snap ring, I am wondering why not all 91 are in that snap ring range? I assumed that Honda used the same method (multi- bit) to cut the trans and switched out sometimes in 92. I have read that quite a few 91's trans. are not in that range. There are a few thousand trans. made in that range, and I assumed again that all of them would go to the 91 first and the earlier model of 92's.

 

[D'Ecosse]

http://www.nsxprime.com/FAQ/Troubleshooting/transmission.htm

The history & resolution is in the FAQ

 

[nis350]

I've read the article in the FAQ and that is why I have the question.

 

[Larry Bastanza]

Did you miss this paragraph in the FAQ:

The snap ring sits in a groove-within-a-groove (actually more of a "shelf" within a groove) machined into the transmission case. In order to cut this complex part of the case the manufacturer used a 3-piece bit; one part to cut the main groove, one part to cut the "shelf" that holds the snap ring within the groove, and another piece to cut the outside of the groove.

During the process of machining a batch of transmission cases they would stop once in a while to measure tolerances. They found that the snap ring groove was cut too wide after the bit was used X number of times because the three pieces that made it up would spread apart a little (several thousandths of an inch make a big difference in transmissions). They kept replacing these multi-piece bits and finally redesigned it as one-piece bit to solve the problem.

HTH,
LarryB

 

[nis350]

yes, Larry. I've read that. My question is why are not some of the 91 trans serial number is not in the snap ring range as specified in that article. I would think that all 91's trans serial numbers would be in that range (J4A4-1003542 through J4A4-1005978). I have read that some 91 X's have trans that are not in that range???

 

[Larry Bastanza]

I think you are making an assumption that the transmissions were installed in serial number order, which is not true. In general the late 91's and early 92's were around the production dates when these transmissions were made, but this is why YOU MUST check the trans number, not the VIN.

So you must not confuse the trans # with the VIN

HTH,
LarryB

 

[nsxtasy]

I think you are making an assumption that the transmissions were installed in serial number order, which is not true. In general the late 91's and early 92's were around the production dates when these transmissions were made, but this is why YOU MUST check the trans number, not the VIN.

So you must not confuse the trans # with the VIN

Since Larry has so much more technical knowledge than I do, I rarely take issue with anything he says - we are truly fortunate to have him here offering advice - but this time I must.

As nis implies, it is true that Honda made a lot of transmissions - roughly 3541 of them - before the machine started going out of tolerance. I don't know WHY this is so, but it is indeed true.

The transmissions in the snap ring range weren't manufactured and used until well into the 1991 model year. Yes, it is true that they weren't installed in serial number order, but before the snap ring range trannies were manufactured, all the five-speed NSXs up to that point left the factory with transmissions with lower serial numbers than those in the snap ring range. The snap ring range transmissions started showing up with the VIN in the U.S. VIN sequence around MT0025xx. I have not heard of a VIN lower than about MT002500 that left the factory with a snap ring range transmission. (The 1991 model year had VINs that went as high as roughly MT003220.)

 

[nis350]

"As nis implies, it is true that Honda made a lot of transmissions - roughly 3541 of them - before the machine started going out of tolerance. I don't know WHY this is so, but it is indeed true."


This is exactly what I was asking. Did they produce these 3541 trans. differently than the ones in the snap ring range? It is not a big deal, I was just curious. Thanks for all your responses.