About 6MT for turbo

There is a tendency on the market to set up 6MT that is usually used in NB8 instead of 5MT that is usually used in NA and NB6.

Of course, Maruha Motors keeps in stock 6MT, but we recommend 6MT for turbo.

Let us explain about the differences between the non-turbo 6MT and 6MT for turbo.
Even if you check the maker’s manual or try to read about it in the explanation about new cars, you won’t be able to find out the details.

Maruha Motors obtained detailed documents from the Miata/MX-5 specialist shop Nogami Project in Kanagawa prefecture. We will try to explain the differences using this illustration as a base.

1. Shot peening process
The “SP” sign seen on the picture stands for shot peening.
Shot peening is carried out to give the product strength and break it in more easily.
The surface is irradiated with shots of particles in different shapes.
When a surface is peened, it spreads plastically. Furthermore, the surface’s mechanical properties change too. This means that it might become harder or its friction might become lower.
It is not known what kind of SP is being carried out in the case of 6MT.

SP is carried out in the case of low gear like that from 1st to 4th gear.
If we talk about turbo, we mean that it can respond to high torque, which means that it can deal with the problem of the broken or chipped gear in the case of an abrupt torque.

Especially at starting time and the time of acceleration the torque is under a big load, that’s why SP is carried out from the 1st to the 4th gear.

The counter gear, the shaft and the main shaft (input shaft) too are treated by SP.

The 4th gear is slightly transformed into low gear.

Gear ratio First gear 3.760
Second gear 2.269
Third gear 1.645
Fourth gear 1.257 1.258
Fifth gear 1.000
Sixth gear 0.843
Reverse 3.564

As you can see, 6MT for turbo is different from the standard, but its price is the same as the standard 6MT’s, that’s why Maruha recommends the 6MT for turbo.


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