Excellent Braking with Maruha's 4 Pot Caliper Kit

Do you enjoy driving? If you feel uncomfortable with loose braking effectiveness and bad pedal feeling, why don't you change your front caliper to Maruha 4 Pot Caliper? It allows you to keep using the wheels in your MIATA and to choose from a wide variety of brake pads. Our customers may enjoy driving in the street and the circuit with Maruha caliper.

Maruha's 4 Pot Caliper Kit has special features for MIATA lovers.

1. Features of the genuine MIATA caliper

Picture 1 above shows you that the genuine caliper has a single piston that is floating-mounted inside the rotor disc.

It moves right and left with the slide pin.
This compact caliper does not interfere with narrow wheels that have small offsets.

We will explain you how the caliper works.
The sliding genuine caliper sandwiches a rotor in between.

Pushing the brake pedal directs the oil pressure towards the caliper piston. The caliper body tends to move outside the car against the pressure. This repulsion against the oil pressure forces the caliper to slide, in other words, the brake pads in the caliper sandwiches the rotor.

The rust stuck on the slide pin interrupts the caliper from sliding smoothly. This is a cause of troubles such as brake pad rubbing.

Though the MIATA includes several models, the caliper piston sizes are all the same.

However, the rotor diameters are different: NA6CE has a 234mm and NA8C/NB (excluding NB8 with a 270mm disk) have 252mm rotor discs.

2. Features of Maruha 4 Pot Caliper

Maruha's caliper body with billet aluminum is much lighter than the genuine ones.
The body housing forging gives our caliper the refined design and enough stiffness.

The stainless steel piston, works as one of the important functions in the caliper, has rust resistance and can prevent heat from transferring to the fluid.

The main feature of our 4 pot caliper is to brake by using the rotor effectively.
See Picture 2 that shows each different area of the pressure against the rotors between Maruha 4 Pot Caliper and a reinforced large single piston caliper.

Pressure areas caused by pistons against rotors.
Red circle-Maruha 4 Pot Caliper piston
Blue circle-the genuine caliper piston

The reinforced brake system puts the rotor rim between brake pads.
As the single piston diameter becomes larger, the width of the rotor that the pads sandwich, turns wider because the single piston tends to push the center of the rotor more than calipers with plural pistons.
Furthermore, the wider the rotor hits the brake pad, the more probable an uneven pad wear.

Not only single pistons have drawbacks. The more pistons calipers have, the more difference in friction coefficient between the pads the rotor in and out.

Have a look at Picture 3. The red circles show the piston positions.
Generally, the rotor-in side causes more friction against the pad than the rotor-out side.
Different diameter pistons have more friction to the rotor-out.

Friction against the rotor in and out sides.

Maruha 4 Pot Caliper is designed to decrease friction.
The caliper makes a great pedal feeling without interfering with the master cylinder as suitably small-sized pistons are used for our product.
Moreover, the NB8 after M/C rotor included in the caliper kit is large enough to sandwich the brake pads effectively between the outer rims.

Although there are many users who use 14 inch wheels, larger-sized rotors have advantages to make the brakes perform better.
You can prevent the brake pads from the overheat condition and the damages by using large sized rotors that's rims work effectively.

Small rotors, controlled by the pads with high friction or the calipers pushing the rotors hardly, are not recommended.

3. Why is the NB8 rotor adopted?

It costs less to supply the NB8 rotor, that's diameter is 270mm and is large enough to be installed into the MIATA as it is in the case of a genuine product.
In addition to this, Mazda supplies the rotors steadily and we can provide our customers with them without stock shortage or overstocks.

The NB8 rotor frees us from the necessity to develop two-piece rotors because the genuine product can be used in every MIATA.
The rotor keeps you from worries about the interference with the hub and about the matches with the wheels installed in your car at present.

4. Solid line-up of front brake pads

A large variety of products is available.


(2) HAWK
HPS-High Performance Street
HP Plus/Autocross

(3) Performance Friction (PFC)
PFC 80 Compound
PFC 83 Compound
PFC 93 Compound

(4) Endless
Type CC-R
Type CC-X
We plan to increase more our product lineup.

5. Pad setting for daily street driving

A lot of customers use Maruha 4 Pot Caliper in daily driving, though it is originally released for circuit.
Everyone may have an experience of driving with radial tires in rain.
It is dangerous to use brake pads with a high friction factor on a rainy day.
They make the tires locked up easily due to the brake system that's performance has been increasing recently.
In order to avoid the danger, HAWK HPS is adopted as the pad included in our caliper kit.
We are convinced that the HAWK pad is easy to handle on streets with its long life and mild braking.

Furthermore, you can support the brake pads steadily with the hollow fittings and the back plates that Maruha 4 Pot Caliper contains. Our product prevents your brake system from odd sounds caused by the brake pads.

6. Keep on using your wheel

Is your wheel installed and suited for MIATA and does it have a diameter of 15 inch, 7 inch J with +35 or less offset?
If so, almost all the wheels are acceptable to be installed with Maruha 4 Pot Caliper.
However, it is true that some wheels are unsuitable for our caliper body.
When you have a question whether your wheel fits the caliper, please feel free to contact us.

7. Separate sale: Mazda Speed slit rotor

You can get Mazda Speed slit rotor as an optional kit.
A slit rotor removes brake pad dust from the rotor surface.

All pads make dust. When the rotors without slits have dust on the surface, the pad abrasive allows it to be detached.

In severe conditions such as race driving, the brake system works under hard conditions.
The slit rotor has an advantage in maintaining the brake performance.
It cleans the rotor surface efficiently by removing dust through the slit grooves.
If you brake frequently, the brake heat forces the pad lubricant to turn gas.
It makes the rotor slide against the pad. As the result of it, the heated rotor disc moves relentlessly like a hot knife through butter. This situation causes brake fade.

The slit rotor is designed as a reinforced disc to avoid brake fade, though it is said that the performance is changed by the differences in width, depth, design, numbers of the groove and so on.
The more slits rotor discs have, the faster the brake pads wear out. It is possible that the slit rotor causes judder and we cannot recommend the street drivers to use it.

The slit rotor works efficiently on circuits.


We arrange the ideal kit and offer Maruha 4 Pot Caliper to our customers with reasonable prices.
Why don't you check "4 pot caliper sale" on the internet? Comparing to the others you will see how affordable our caliper kit is.
The caliper is deeply related to the brake that is a safety device.
In order to prevent dangers by bad installation or wrong processes, we highly recommend you to have a professional mechanic set up the caliper kit.

Kit Component (*1): caliper, rotor, brake line, brake pad (*2), hollow fitting plate, back plate, mounting bracket stay, bolt&washer
(*1) A fluid is needed separately.
(*2) HAWK HPS belongs to the kit. Other pads you prefer can replace it. When you buy the pads you need, the cost difference with the HAWK pad is added to the kit's price. We also have different kinds of pads including Maruha's original pad. For further information, see Maruha 4 Pot Caliper Details page.

Types of Maruha 4 Pot Calipers
Maruha 4 Pot Caliper Kit with NB8 rotor
Maruha 4 Pot Caliper Kit with Mazda Speed slit rotor
Maruha 4 Pot Caliper Kit: rotorless

We have great items. See Maruha 4 Pot Caliper Details page.


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