Final gear 4.6 Mazda Miata NA8/NB

The characteristic of the final gear is to lower and raise the gear.

Most of the users consider important the acceleration, in other words the first, second and third gear. They want to set aside the fifth and sixth gear. Which means that the pros and cons mix.

This is the difficult point when choosing the final’s gear ratio.
However, the change of the gear, especially low gear change in the case of the powerless Mazda Miata, occurs frequently. Considering important the acceleration, the time-up on circuits and gymkhana, many users are trying to find an optimal solution.

We, at Maruha Motors, have set up the 4.6 gear which aims for this optimization.

This is the reason why we designed the 4.6 final gear.

For reference

NA8 early models genuine final 4.1 (one part RS 4.3)
NA8 later models (Sr2) genuine final 4.3
NA8 AT genuine final 4.1

NB8 6MT genuine final 3.99
NB6 5MT genuine final 4.3
NB AT genuine final 4.1

All these low gears are effective for NA8/NB vehicles.

Speedometer calibration

When we change the final, we also have to think about the speedometer’s calibration.
If you use the driven gear for 4.6 set up by Maruha, the most effective match is the 4.6 changed final.

We can show you the results we got from our DYNO-RACE (by DimSport).

We did the following tests on an NA8 vehicle.

  1. 4.1 + driven gear for 4.1
  2. Final 4.6 + driven gear for 4.6

We were monitoring the speed from the rotating roller.
At that time we could also confirm the meter’s speed.

  NA8C final 4.6 / driven 4.6 NA8C final 4.1 / driven 4.1
Vehicle meter Roller speed/Measured speed Roller speed/Measured speed
40kmh 37kmh 38kmh
60kmh 56kmh 57kmh
80kmh 74kmh 76kmh
100kmh 92kmh 94kmh

There’s not too much difference between the readings and the vehicle meter’s data.

You can simultaneously use it with the driven gear.

To learn about it more, check out this page about the driven gear unit.

Set parts

We offer a wide product line-up of set parts containing the 4.6 final gear, LSD and other parts that are necessary to the installation.
Check it out here:
Set parts/ LSD&final Final gear NA8/NB
Set parts/LSD&final Final gear NB


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