LSD for Mazda Miata NC (MSP model)




The metal LSD produced by our company is finally on sale.

There was almost no relation to the NA/NB parts when developing the parts for NC and for this reason everything had to be done from zero.

Even the LSD itself has a totally different dimension. Some parts of the bearing are the same as in the case of NA/NB, but the main part is exclusively set up just for NC.

LSD (MSP model) for NC is a light metal type that is easy to drive.

The LSD is a mechanical type. Its goal is direct torque transmission, which is not possible in the case of Torsen LSD. It gives a feeling of safety when turning on the traction fully and during cornering.
However, the chattering caused by the LSD might shy away the users that are not used to it.

The joy of turning by steering and traction (accelerator work) is typical for FR vehicles like Miata/MX-5.

There are many users who dislike this chattering sound and for this reason prefer a carbon type. This means that the users make a difference between the chattering sound caused by carbon and by metal. But what if the chattering could be stopped even by metal?

The MSP model is mechanical driven type, but it can be driven easily and can respond to this kind of LSD.

The characteristics is the metal disc

The disc’s diameter for NC is 95mm.
The base is S2000.
First we process the S2000 LSD and then start the production.
If we compare the composition of NC and S2000, we can imagine the LSD’s capacity for NC.

Furthermore, when considering cost, durability and after-service, we decided to use a metal-type.
There are 2 types of teeth on the metal disc - inner and outer teeth
The metal discs get crimped and torque gets transmitted.
However, bad quality discs may be the reason for chattering.
That’s why we made the outer teeth without grooving.
The inner teeth are spiral shaped and in the case of centrifugal force they can maintain the oil.
This disc’s equalized surface leads to a smooth differential motion.

Like this we managed to transmit the cam torque.

We recommend a 60°― 60°2 WAY pressure ring.
Maruha’s style is a 2WAY for the FR Miata/MX-5 accelerator work and control.

Though, we prepared the 1.5WAY too for those who would like to use it.

Maruha MSP model’s differential motion characteristics

Low rpm ・・・light torque transmission (chattering doesn’t occur easily)
Running・・・responding to the acceleration work; there is a certain torque transmission (equalization of the disc contact pressure)

This is the real charm of the MSP.
It allows an exquisite traction control.

The final gear’s flexibility

The NC final gear rate is AT・MT 4.1.

Except this there is no NC genuine final setup, so you might want to use the final gear from NA/NB. However, there is a problem – the ring gear’s thickness.
The NC ring gear is thin, but the NA/NB ring gear is thick.
The differential’s center is pinion gear and if the ring gear’s thickness is different, the LSD’s position changes.

Ring gear in the hand (thin) – for NC
Installed gear (thick) – for NB

In other words, if we install the ring gear (for NA・NB), which is thicker than the genuine NC one, the difference in the thickness will offset the LSD’s position.
The branch, which is installed on the left and right sides of the drive shaft, changes – the right shaft penetrates deep, the left shaft’s inserted part becomes shallow.
The improper insertion cannot grant the oil seal’s appropriate clearance and there are cases when from the left-side flange oil leaks.

Final installed in the LSD for NC without offset structure
Right shaft – deep penetration
Left shaft - shallow insertion

From the beginning we offset the LSD position, carry out centering while using spacer. When changing to NA・NB final, we remove the spacer and secure the centering.



Insertion of the adjusted shaft
Equalization of left and right – in the center 4.3 final

By this it becomes possible to use an NA/NB final in NC.

In the case of reusing the NC genuine final, you have to purchase a separately sold spacer and bolt set.
The spacer and the special bolts are longer.

Set parts

You can purchase sets of genuine parts and each type of final. Please contact us for further information.

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Maruha Motors Co., Ltd.
Ushizuma 2095-6, Aoi-Ward
421- 2106 Shizuoka city, Shizuoka prefecture
Japan
TEL: 0081-54-294-0076
FAX: 0081-54-294-1312
E-mail: info@maruhamotors.co.jp