I have been searching all night and morning for the differences in the two part numbers and they are all the same from what I can tell. Two different websites selling OEM parts for Infiniti/Nissan parts are selling the exact same transmission part but 2 different part numbers.

I have a local "too good to be true" listing of a G37 6 speed trans at 30k verified miles. It shifts super smooth in all gears and literally looks exactly the same minus the casting and sticker on it... He is selling it as a CD009 but where that sticker normally would be saying CD009, it says JK41A. I googled everywhere and it comes back with the same fitment on all the VQ37HR/VQ35, 350z, g37 etc etc... Is there any difference or am I missing something obvious??

Long story short, what is this???

 

Buying it as a spare or to set aside for me?

My uneducated guess would be that you're right. Have you looked at other Infiniti/Nissan stuff to see if common parts get marquee numbering under the Infiniti banner?

 

Haha yeah, this will actually be a nice spare for my SC or G37 lol, it'll fit both. But, the G forums are worthless, they hardly know where the battery is, CL is where the brains are at.

 

The JK41A is the transmission for the G37. It will have the internal concentric slave cylinder/clutch release bearing, rather than the external slave cylinder and clutch fork/release bearing setup that the CD009 has. You can specify that transmission when purchasing a Collins kit, so I imagine it can be used. I imagine with it being a newer transmission than the CD009, it would have the same synchro setup as the CD009, so I wouldn't worry there. I have just read on a few different places that the CD009 with external slave is easier to do. Although I can't remember what the reasoning was.

 

^^^ Ahh you're right, thank you! This is good news. Good deals are out there!

 

No problem! Just FYI though, that the 370z concentric clutch slave cylinder can barely handle the stock pressure plate. When upgrading clutch and pressure plate force (which you will for sure be doing), you will need to get an upgraded Heavy Duty clutch slave cylinder. Zspeedperformance makes them for $325..

 

So, what you have is an 09' or newer G37/370Z 6-Speed. The JK41A uses an internal concentric slave with an external bleeder rather then a fork and external slave. It also has an upgraded helical cut reverse gear and triple cone syncros in 1st and 2nd. One down side is the syncros in 5th and 6th are steel instead of brass an sometimes have grinding issues (sometimes imply's bad driving by people)

LoveSC is right about the concentric internal slave, they are complete **** and after a few clutch kicks the factory plastic housings break and cause major issues, anything from grinding, to being stuck in a gear, to vibrations.

If you run this transmission, you will definitely want the Z-speed Performance upgraded concentric slave. They are a solid steel casing and a better bearing. Last I saw they were about $560 but some people are finding them for less, so more power to them.

Either transmission (CD009 or JK41A) is a good option, both good for just shy of 800 HP without upgrades, and with a twin disc clutch setup it almost bullet-proof for most people. I would aviod a single disc due to clamping force and theoretical issues later on, but honestly, just make sure to upgrade the concentric slave and enjoy the thing.

I happen to have both CD009 form an 06' G35 and a JK41A from an 09' G37.. Here are some pic of the two transmissions I have to compair


This is the 09' G37 JK41A


This is the 09' JK41A


JK41A side case stamp


JK41A rear tailshaft stamp


JK41A concentric slave and bleeder lines


And here is the 06' G35 CD009


06' G35 CD009 transmission


CD009 side case stamp #2 signifies updated internals


CD009 rear tailshaft stamp


CD009 throwout bearing and fork.

 

Awesome info, thanks for stepping in man! Sucks about the 5/6 syncro's but it only has 30k and was pretty much free so even with the Z-Speed package I'm still ahead, no worries.