HKS Miata Transmission

[fwdtamiya]

Here's a bit of an interesting historical thing I came across recently. An HKS cross trans that bolts up to the miata transmission housing. Google-fu says it's a 3 speed. Though what I had been told long ago is that a cross trans means 3 gears are replaced with shorter ratio ones. To me this never made any sort of logical sense about not replacing all the gears, while the transmission was in pieces anyway, so that ratio differences between 3 and 4 for instance weren't a mess, or why the final drive wasn't just changed instead, which would be a much cheaper and faster method. I'm beginning to think "cross" is just engrish for "close." So I'm not quite sure if this is actually a 5 speed or a 3 speed. Anyone have knowledge about that? Here are the pics:


メーカー：HKS関西
商品名：HKS関西 3速クロスミッション
マツダ NA6 ロードスター用

https://page.auctions.yahoo.co.jp/jp/auction/j570655341

https://i.imgur.com/SQjfgiC.jpg

https://i.imgur.com/5WuVHLv.jpg

https://i.imgur.com/a17wZqw.jpg

https://i.imgur.com/ATEaOtv.jpg

https://i.imgur.com/sBkrT15.jpg

https://i.imgur.com/RvTGmVM.jpg

[MaRcOp01o]

Well holy hell I didn’t know this was a thing! But in my Eunos I have the mazdaspeed close ratio gearing in my trans and man it seriously makes the miata a whole different animal.

[bogaut]

yea i think its just close ratio 1-3

[NotableGuest]

Well holy hell I didn’t know this was a thing! But in my Eunos I have the mazdaspeed close ratio gearing in my trans and man it seriously makes the miata a whole different animal.For the better I assume? I always had an eye out for that MS set. Do you have the MS final drive gear too?

Sent from my VS996 using Tapatalk

[MaRcOp01o]

For the better I assume? I always had an eye out for that MS set. Do you have the MS final drive gear too?

Sent from my VS996 using Tapatalk

Yep It’s the whole shibang. Makes a nice transmission whine too and the gearing is spectacular I can’t stress that enough you feel like a race car flying through 3rd 4th and 5th.

[kung fu jesus]

Yep It’s the whole shibang. Makes a nice transmission whine too and the gearing is spectacular I can’t stress that enough you feel like a race car flying through 3rd 4th and 5th.

Is that a dog box with straight cut gears like this Quaife sequential?

https://youtu.be/Nn02RwrNIzI

[MaRcOp01o]

Is that a dog box with straight cut gears like this Quaife sequential?

https://youtu.be/Nn02RwrNIzI

The one in the Eunos is a regular 5-Speed but has polished gears and shorter 3-4-5 gear ratio. The shifts are very smooth and direct

[kung fu jesus]

Neat.

There is a shop near me that rebuilds Miata boxes. Some of the local guys running V6 swaps, bigger turbo/power Miatas are using their boxes and have nothing but great things to say. I believe they have 2 or 3 levels of builds, but their pricing is actually pretty good for an OE upgrade.

https://walter-motorsports.com/

They near Road Atlanta.

Quaife sells close-ratio gear sets, or used to IIRC.

[MaRcOp01o]

Neat.

There is a shop near me that rebuilds Miata boxes. Some of the local guys running V6 swaps, bigger turbo/power Miatas are using their boxes and have nothing but great things to say. I believe they have 2 or 3 levels of builds, but their pricing is actually pretty good for an OE upgrade.

https://walter-motorsports.com/

They near Road Atlanta.

Quaife sells close-ratio gear sets, or used to IIRC.

Dam that’s pretty sick! I do know you can swap in the NCs gearing while using the NA/NB housing.

[lifebyevan]

Dam that’s pretty sick! I do know you can swap in the NCs gearing while using the NA/NB housing.

What is the benefit of the NC gears, do you know? Never heard of putting the NC gearing in the NA?NB housing but I'm interested to know more.

[kung fu jesus]

I don't know that anyone has done that, but I do remember the physical dimensions of the gear sets are similar.

[MaRcOp01o]

What is the benefit of the NC gears, do you know? Never heard of putting the NC gearing in the NA?NB housing but I'm interested to know more.

I was told by an SCCA Gentleman that he was running in his NB his NB rear housing cone and the bell housing from the NB but he had the NC 5-Speed gear set.

At the time I was 17 years old and only had my miata for a month so hearing that sounded crazy cool but I never looked into it at the time.

[kung fu jesus]

Yeah. If it were easy or common, there would be a ton of them out there. $1200 for an improved rebuilt unit (local-ish to me) is the "easy" button.

[HarryB]

This has been discussed again AFAIK

https://mazdaroadster.net/showthread.php?14652-NC-transmission-in-NA-NB

Not sure if do-able or not, but what would the benefit be? I doubt the NC 5-speeds are any stronger.

[lifebyevan]

This has been discussed again AFAIK

https://mazdaroadster.net/showthread.php?14652-NC-transmission-in-NA-NB

Not sure if do-able or not, but what would the benefit be? I doubt the NC 5-speeds are any stronger.

Here is the info from the Nielex website, in case the website link goes bad in the future:

"NCEC 5-speed mission SWAP (for NA / NB)
revised edition
¥
200,000- + tax (as of February 2018) The cost of desorption is not included.
Vehicle type: NA6CE / NA8C / NB6C / NB8C

Roadster 5-speed MT has been equipped with the same model for three consecutive generations from NA6CE to NCEC.
However, its contents continued to be improved to meet the quality required by the changes of the times, and it made great progress.
When the model was changed from the NA type to the NB type, double-cone sync for the 1st and 2nd speed was adopted, and the gear change to the 2nd speed, which was awkward with the NA type, was smoothed.
In NCEC 5th speed, further ripening of shift feel and in response to high torque associated with 2L engine, triple cone sync to 1st to 2nd speed, double cone sync to 3rd speed, carbon synchronization to 4th speed In addition to the adoption, improvements such as low friction in the shift operation system have reduced the feeling of roughness of the metal system that is transmitted to the palm of the hand, and realized a nice shift operation.
As a recent trend, the NA type has a strong need to replace missions that have overused 200,000 km, and the reality is that overhauls of handheld missions, replacement of used missions of the NB6C, or replacement of the NB8C 6-speed MT are being dealt with.
Nevertheless, the NB8C 6-speed MT is also a bottleneck for long-term ownership because it is difficult to obtain new ones.
In particular, the 6-speed MT of the NB8C was not highly evaluated from the beginning due to the shift feel and gear ratio.
Since 1st gear is super low, you have to shift up to 2nd gear immediately after starting, and to be honest, it will be difficult to start and you will start to rotate at 2nd gear.
In addition, the 6th speed, which is overtop, has no torque like the shift for fuel-saving cruises on highways, and is not easy to use.
Nirex has already established a menu for diverting new NCEC 5-speed MT to NA6CE to NB8C 6-speed for 5 years, and has done many NCEC 5-speed MT SWAP constructions.
We take pride in achieving the highest level of customer satisfaction.
What is more noteworthy is the movement of the NB8C's NCEC 5-speed MT, which should be called a breakup to the NB8C 6-speed MT .
We already have several SWAP cases.
Then what are the advantages of the NB8C's NCEC 5-speed MT?
That is, when shifting up from first gear, it is possible to connect to the top gear smoothly and efficiently without removing the torque band.
As a result, the torque band of each gear is wide, not busy, and long-lasting acceleration continues.
Another point is that the NCEC 5-speed MT is a high torque compatible mission for 2L engines.
It is the best choice not only for 1.8L NB8C but also for vehicles with high power tuned engine.
It can be asserted that this NCEC 5-speed mission SWAP is the best menu for mission tuning up of NA6CE to NB8C.
* 1
NCEC 5-speed mission SWAP requires NA / NB6C 5-speed mission case.
Especially in the case of NB8C, it is necessary to procure a used NB6C mission case in advance.
Note 2) The
diff / final value may need to be changed depending on the driving stage.
Note 3) In
addition to the above new menu, we also handle used NCEC 5-speed mission SWAP, but it is a prerequisite that you bring your used mission. Please contact us."

[MaRcOp01o]

Looks like random SCCA Miata Man was right!