High Spec Maruha Power Metal Bearing

A metal bearing that is a plain bearing to rotate crankshafts and connecting rods has a huge effect on engine performances and its lifetime.
You need to select metal bearings with higher quality, more superb capacities and more durability than others. In addition to them, their reasonable prices will attract you.

Maruha Power Metal Bearing, we have released, includes 3 sizes to meet your needs from fine tunings to race ones, but the same price range as the genuine MIATA bearing, although our product has higher quality and performances than the others.

When you use Maruhafs bearings, it is obvious that you would be fully satisfied with them.






[Features of Maruha Power Metal Bearing]

1. Oil groove, the troubleshooter

Our upper and lower main bearings have oil grooves to gain the oil feeding into the oil holes on your crankshaft journal.
The awful improvement can increase the oil circulation to the conrod bearing that works under more severe conditions than the main bearing.
The grooves also help Maruhafs bearings to be used to tuning engines that drive in the hardest environments.


The red arrows show the oil flow.

Engine troubles are mainly caused by damage in connecting rod bearings, such as the relentless hard vibrations, the bearing seizing by the poor oil circulation and so on. Increasing the oil pressure and quantity to improve the oil feeding is a general way to prevent the damage.


One of the oil holes on the crankshaft journal is a 180-degree contract to the other.
The genuine bearing has only one oil groove in the upper side, it means that just one of the holes can supply the oil to the crankshaft journal at all times, though the lower metal bearing will expose itself to damage unless the oil is sent to it.

In contrast to the genuine, the oil can circulate inside Maruhafs main bearings because both of our upper and lower bearings have grooves that are allowed to send the oil to the 2 journal holes.
The grooves promote more oil circulation to the connecting rod bearing.

The genuine and genuine-shaped bearings
There is an oil groove in the upper bearing only.
One of the 2 holes in the crank journal can feed the oil.
Maruha Power Metal Bearing
The bearing ring groove helps the 2 holes to send the oil into the crankshaft.
It allows more oil flow to the conrod bearing in short.
Your engine operates at higher rev ranges, more centrifugal force generates.
It causes the poor oil flow in the crankshaft journal.
However, our bearings can be fully operated with the grooves even in severe conditions.


The red arrows: the oil flow/ The blue arrows: the direction of the centrifugal force
Centrifugal force caused by high revolution drives the oil to flow back around to the crank journal.
The conrod bearings have a risk of being damaged unless the oil circulates inside the journal against the force.

2. Durable copper based alloy F112

The appearance of small but high-powered engines had increased bearing loads.
Consequently, people longed for something instead of bearings with sintered alloy and aluminum bearing alloys that had been widely used but that could not work under the heavy loads.

Copper based alloy F112 used as main and connecting rod bearings of high-powered machines such as racing cars, heavy-duty tracks and large industrial machines is excellent to resist high speed driving and heavy loads.
The material gains popularity in the United States, where is the earliest country to spread high-powered engines. Furthermore, it is introduced to Europe to be used widely.

Although it takes a huge equipment cost to produce the alloy with the high tech, why does F112 become popular in a lot of countries?
We will show you its structure and features comparing to a sintered alloy that is copper-based.

The kelmet made of sintered copper lead alloy powder cannot withstand heavy loads.
The copper alloy powder bonds are weaker than F112 as the powder is sintered at lower temperatures than the copper melting point. It tells you the powder bonds are easy to break under high loads.

F112 consisted of the overlay metal and the copper based alloy on the backing steel plate has the copper alloy bonds formed vertically.
Some of them also spread from the main stems like branches.
The lead alloy acting as lubricant disperses among the bonds.
Heavy loads pressuring vertically are hard to damage the F112 structures.

F112 has unique structures like stems and branches.
They bring this alloy outstanding performances in the load bearing and the seize resistance.

The copper based alloy F112 has superior corrosion resistance to the sintered alloy.
The overlay surfaces prevent both of them from getting damaged.
However, the sintered alloy is likely to have corrosion after the overlay is worn out.

The lead that forms the lead bronze layers beneath the overlay surface has corroded toward the inside.
It causes the layers to become caves destroyed by the loads.

The sintered alloy corrosion advances because the lead bronze layers are arranged in rows.
In contrast, the dispersed lead of F112 can avoid the deep corrosion.

3. Surface-overlay plating


The cross-section of Maruha Power Metal Bearing

The overlay metal covers the bearing surface to enhance the oil absorption and the running-in lubrication.
Copper based alloy F112 has excellent load bearing capacity, but at the same time, it is less good in several performances like the surface performance, the oil absorption and the lubrication that are necessary to operate the bearing completely.

The overlay metal can improve these abilities and it prevents the seize damage caused by the shaft misalign, the poor surfaces of the crankshaft and something in the oil.

4. You can choose from 3 sizes

Different size setup is able to get adequate clearances to maximize your bearing performances.

The genuine MIATA bearing has only one setup, Standard Size. It means that you need plural sizes to have exact clearances.

Maruha has examined data on bearings comprehensively, including the genuine bearing size.
It brings you the 3-size bearings that can cover a range of frequent use. Our product meets a lot of customers' needs.

We have "Standard Bearing Kit" designed to take the middle of the baseline production allowances. For more information, see

5. "Introduction of Standard Bearing Kit" page.

- Size of Maruha Power Metal Bearing Line-

Main Bearing
Size Range
A 2.002-2.006mm
B 2.006-2.010mm
C 2.010-2.014mm


Connecting Rod Bearing
Size Range
A 1.500-1.504mm
B 1.504-1.508mm
C 1.508-1.512mm

6.Sales unit

You can buy our bearings from one set of the upper and lower bearings, which is the minimum unit for sale.
It is also welcomed to order the units you need to complete the overhaul.

Main Bearing (Upper & Lower/unit)

Size Range
A 2.002-2.006mm
B 2.006-2.010mm
C 2.010-2.014mm


Connecting Rod Bearing (Upper & Lower/unit)

Size Range
A 1.500-1.504mm
B 1.504-1.508mm
C 1.508-1.512mm

6. Introduction of Standard Bearing Kit

Maruha sells Standard Bearing Kit designed as the mid size bearing, which is most-frequently used to take the middle ranges of the genuine production allowances.


10 Main Bearings/car
Kit Component
Ax1unit/ Bx3units/ Cx1unit
A: 2.002-2.006mm B: 2.006-2.010mm C: 2.010-2.014mm


8 Connecting Rod Bearings/car
Kit Component
Ax1unit/ Bx2units/ Cx1unit
A: 1.500-1.504mm B: 1.504-1.508mm C: 1.508-1.512mm

This kit is designed to be in the middle ranges by combining the upper and lower bearings.
For example, when you merge the upper A and the lower C, they form the mid size bearings, as well as when the upper and lower Bs are connected.
You can change these combinations as your preferences to pursue accuracy.

We never force you to buy the fixed kit. Our customers can have your own original kits composed by sizes that you need. When you place the special order, let us know the essential information including which sizes and how many units you want. Keep it in mind!

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