Bearings are widely used in various types of machinery. It can be said that no running machine can do without bearings, and bearings are even the key components of motorcycles.

Due to the fact that most of the mechanical parts of motorcycles are exposed, they are subject to the severe test of high-speed rotation in harsh driving environments. This requires that motorcycle bearings have good durability and high sealing performance to extend the service life of motorcycles.

Motorcycles vary according to their models and structures, but each motorcycle is generally equipped with 20 to 30 bearings. These bearings are used in important rotating parts that support driving, such as engines, transmission devices, and wheels, and they play a role in reducing friction and ensuring that the engine's power is effectively transmitted to the wheels.

The performance of motorcycle bearings

● Smooth rotation is achieved through low friction and low vibration;

It has foreign object resistance and high rigidity;

It is necessary to ensure durability, etc.

The bearings used in the engine and transmission of motorcycles are required to have foreign object resistance and high rigidity as they are used under conditions of high temperature, high-speed rotation and significant impact loads in a foreign object environment. In addition, the bearings used for wheels must be suitable for the vehicle to operate in various terrains and for different purposes. Therefore, they should also be durable against water, mud, etc.

(1) Engine Application

Crankshaft

Main bearings: Ball bearings, cylindrical roller bearings

Connecting rod: crank pin cage bearing

Timing operation

Camshaft: needle roller bearings, ball bearings

Auxiliary equipment

Starter: Needle roller bearing

Oil pump: Needle roller bearings, ball bearings

(II) Transmission Application

The driving shaft and the transmission shaft

Ball bearings, roller bearings and slotted lightweight plastic cage bearings for idlers

Clutch

Clutch release bearing

Shift gears

Ball bearings, needle roller bearings

(3) Chassis Application

Chassis

Ball bearings, needle roller bearings, tapered roller bearings, angular contact ball bearings, thrust needle roller bearings

Universal joint

Cross universal joint

Common models of motorcycle bearings

On motorcycles, ball bearings are generally applied in the internal transmission system of the engine and the wheels, flat ball bearings are used on the front fork, and needle roller bearings are applied on the crankshaft connecting rod and some transmission gear shafts.

Generally speaking, for vehicles with a capacity of 100cc or less, the front wheels are 6200, 6201, 6300, or 6301, and the rear wheels are 6301.

For 125cc and 150cc vehicles, the front wheels are 6301, and the rear wheels are 6202, 6302, 6200, 6201, 6202, 6203, 6204, 6205, 6206, 6300, 6301, 6302, 6000, 6001, 6002, 6003, 6004, 62/22, 62/28 respectively 62/32, 63/22, 63/28 and 63/32 are also commonly used.

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The causes and analysis of early damage

Bearings on the front and rear wheel hubs and the rear chain disc

★ ★ Due to the fact that car owners wade too deep into water or frequently wash their cars during daily use, water enters the bearings, causing the grease inside the bearings to gradually lose its effectiveness. This results in severe wear of the rolling grooves and balls inside the bearings, with a significant increase in the clearance.

If the front and rear wheels are assembled too tightly or too loosely when leaving the factory or being sold, over time, it will cause unstable driving, bearing jamming or loose bearing displacement, damage or detachment of the ball cage, resulting in excessive clearance, causing the brake disc to rub against the wheel hub and increasing driving resistance.

The bearings on the rear sprocket disc are prone to water ingress or are adjusted too tightly or too loosely, both of which can cause damage. Therefore, car owners should pay special attention when washing their cars or passing through deep water pits and check and maintain them in a timely manner. If it is damaged and needs to be replaced, it must be done properly. Adjust it until the wheels turn smoothly and there is no obvious clearance.

2. Crankshaft connecting rod large and small end roller bearings and ball bearings on both sides

Generally, two-stroke engines are more prone to damage. The main reasons for the damage of the large and small roller bearings of the connecting rod are: poor quality of the engine oil or too little oil quantity.

When the engine is in operation and the temperature is too high, it intensifies the frictional heat generation and surface softening, leading to premature fatigue and spalling of the working surface. The spalling particles enter the cage of the steel column, causing operational obstruction. The rollers exert abnormal loads on the cage, accelerating the wear of the cage, causing it to break and crack, and the crankshaft connecting rod to seize up.

If the engine oil replaced for a four-stroke engine is of inferior quality or has been in use for too long, the lubrication efficiency will decrease, leading to increased wear and easy formation of impurities that can clog the oil passages. After the assembly or major overhaul of a new vehicle, due to the site not being clean enough or hard foreign objects carried by the tools used for calibration entering the bearing raceway, the rotation of the bearing is blocked. The misalignment of the crankshaft during press-fitting or the misalignment of the crankshaft during installation increases the rotational load on the bearing, causing damage.

3. The bearings on the wheels of the chartered vehicle

Generally, after chartering a car, the shock absorption is a single support with a relatively large load capacity. If the speed is not reduced in bad road conditions, it is easy to cause wear and tear, affecting the service life. When washing the car, water is likely to enter, so be careful.

4. Upper and lower bearings of the directional column

Due to the failure of the front shock absorber, insufficient lubrication or inappropriate fastening force between the upper and lower parts, the balls may break or the working surface of the balls may peel off, causing the steering wheel to become rough or deviate, which affects the safety of driving.

In conclusion, bearing damage is mainly caused by poor lubrication, improper installation, improper clearance fit and harsh operating environment. If not detected or repaired in time, it will cause significant losses or affect the safety of train operation. Therefore, manufacturers, dealers, repair shops and car owners are requested to pay attention to prevent such accidents from happening.

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