Oil seals, which are built into parts that rotate and stroke in the motorcycle, play a role in keeping oil and grease from leaking out while minimizing friction loss during operation. Therefore, if the oil seal is worn out due to aging or foreign contamination, it must be replaced as soon as possible. When removing a press-fitted oil seal, use a suitable tool to make the work more efficient. Oil seals that prevent oil leakage also require lubrication

Oil seals require lubrication to prevent oil leakage.

A seal puller is a tool to remove the oil seal by inserting the tip of the nickel behind the oil seal. With a flathead screwdriver, the tip can easily come off the oil seal. However, this puller has a key-shaped tip that digs into the back of the seal, making it difficult to remove. It is also effective to apply a force from a right angle against the oil seal surface.

The seal puller has a design that looks exactly like a pickaxe or an ice pick. It can be used to remove not only oil seals but also O-rings. This is a STRAIGHT product, a tool shop.

Since the seal holder part of the outer tube is thin, it may crack when the force is concentrated on the fulcrum part, whether using a screwdriver or a seal puller. Therefore, it is helpful to place a material that can bridge the seal holder part separately from the puller, and distribute the load by receiving the puller here to prevent damage.

The list of locations in a motorcycle where oil seals are incorporated includes front and rear wheels, engine, front and rear suspension, and almost any other part of the motorcycle that rotates or reciprocates. Oil seals are given the contradictory role of acting as a bulkhead for the oil while the parts operate. The oil seal equipped in the wheel hub is required to prevent the grease sealed in the wheel bearing from leaking, while at the same time preventing water from penetrating the grease side when driving in the rain.

The same goes for the front fork and engine oil seals. When the inner tube strokes or the output shaft rotates, it is important to keep the fork oil and engine oil from leaking outward.

A rubber oil seal performs its sealing function when its seal lip touches a moving or rotating part. There is a thin spring inside the seal lip, and constant pressure is applied by the spring to tighten the shaft.

While it is important not to leak the oil inside, lubrication between the shaft and the oil seal is also important. When a completely degreased and cleaned shaft rotates in contact with a degreased seal, it creates a resistance similar to erasing letters with an eraser. This not only causes friction loss, but also leads to wear.

Therefore, the portions where oil seals are used must also need to be properly lubricated. When greasing the wheel bearings, you may want to clean the oil seals with parts cleaner and a rag in parallel. The final step in that process is to apply a clean grease to the seal to reduce friction loss. In the case of oil seals used in engines, the engine oil in the crankcase lubricates the seal lips when it comes in contact with it.

The same applies to the suspension when it strokes. When the inner tube with fork oil adheres to the oil seal, it slides over the oil seal area, which causes the oil seal to have a moderate amount of oil on it. Oil leaks are not good, and if you are too careless and wipe off too much oil, you may end up damaging the oil seal.

However, it is important to note that too much oil in the oil seal can cause dust and dirt to adhere to it, and these dusts can become abrasive, damaging the seal and the shaft. When removing the axle shaft collar from the wheel, some riders may have seen a groove at the oil seal lip of the collar. It is often the case that gravel gets caught in the contact area between the lip and the collar, and it is not uncommon for the gravel to be scratched by the collar. Grease reduces drag, but when the grease is mixed with grit, it acts like a compound. It is important to apply the grease for lubrication without excess or deficiency.

How to remove the seal to avoid damaging the seal assembly?

This is a flathead screwdriver with a bluntly rounded tip for removing seals. It is a special tool to remove the seal from the brake caliper. I think I can make a similar homemade special tool by modifying a flathead screwdriver that I no longer use.

It is a common problem to scratch a part when you try to stick a pick tool into the seal groove to remove a piston seal that is stuck in the groove. This seal-removing screwdriver is designed to prevent scratching the body of the brake caliper when prying off the seal.

Oil seals can be used for a long time with proper maintenance, but if the seal lip is damaged by hardening of the material over time or by the bite of foreign substances including dust and dirt, it can cause oil leaks. In the case of front fork and rear shock oil seals, the hard chromium plating on the inner tube and damper rod surface can rust, and the rust can damage the lip, leading to oil leaks.

Oil seals that have leaked oil or grease must be replaced, but only if done skillfully. The fitting on the outer circumference of the oil seal is press-fitted into the wheel hub for wheels or the outer tube for front forks. Due to its nature, it cannot be easily removed. There is also a tendency to try to forcibly remove oil seals that are difficult to remove, which in some cases can damage parts of the motorcycle. This is the point where it differs from parts fixed with bolts and nuts.

In fact, there have been cases where a flathead screwdriver was used as a fulcrum to pry the edge of the outer tube when removing the front fork oil seal, and the outer tube side was pushed by the screwdriver and cracked. There have also been cases where a pick tool was used to remove the piston seal of a brake caliper and scratched the seal groove and the inner wall of the caliper.

In order to avoid such problems, it is important to select the right tool when removing the oil seal. One of the products is a pickaxe, a seal puller shaped like an ice pick. The sharp beak is inserted into the underside of the oil seal, and the seal can be removed using the principle of leverage. With a flathead screwdriver, the point of action in contact with the seal and the point of force at the grip is on a straight line, but with this type of seal puller, the point of force and the point of action are orthogonal, making it easier to apply force. However, a fulcrum to support the puller body is necessary, the same as when working with a diverting screwdriver, so care must be taken not to concentrate the tension if the wall thickness of the area where the oil seal is press-fitted is thin.

There is also a tool called a seal removal screwdriver that is suitable for removing brake caliper seals and O-rings. At first glance, it looks like a flathead screwdriver, but the tip is smoothly rounded and the risk of damaging the caliper is greatly reduced when it hits or rubs against the seal groove when floating the seal or O-ring. Also, when pulling on the O-ring when attaching it to the shaft, even if it gets caught on the tip, the O-ring itself will not be damaged. By utilizing these tools, you can avoid scratching your motorcycle when you intended to replace only the oil seal.

You'll be extremely lucky if you can replace the seal without removing the shaft.

This is a shaft-type seal driver that can be removed even when the shaft has penetrated the oil seal. If the oil seal diameter is large, as is the case for automobile crankshafts and camshafts, some width of the blade to hook the seal is acceptable, but if it is used for motorcycles, a narrower width may be more convenient.

Depending on the distance from the blade and the fulcrum, the position of the fulcrum can be slid and its distance can be adjusted. Push the blade in through the gap between the shaft and the oil seal lip, hook it inward, and pull out the seal in a manner similar to leverage. If this means can be used, it will save a lot of time and effort to disassemble the engine. Be careful not to damage the shaft when inserting the blade.

When performing an oil seal replacement, the extent to which the work involved in replacing the seal is expanded can affect the difficulty and motivation of the task. Both the change shaft, which connects to the shift pedal, and the output shaft, which attaches to the drive sprocket, have shafts protruding from the engine body, and the oil seal is built into the base of the shaft.

If you notice oil oozing from the back of the drive sprocket and remove the sprocket to determine the cause, you should want to remove the oil seal as soon as possible, but since there is an output shaft in the center, you cannot use a screwdriver or pickaxe type seal puller. In this case, the normal procedure is to disassemble the engine, pull the output shaft out of the crankcase, and then remove the oil seal.

However, I'm not comfortable with the idea of having to disassemble the engine when there is nothing wrong with the cylinder head, transmission or clutch. As a result, you may be tempted to grease the contact surface between the output shaft and the oil seal lip as a stopgap, even though you know it is useless.

A shaft-type seal puller may be useful in such cases. With this puller, a thin plate with a bent tip is inserted through the gap between the shaft and the seal lip, and hooked inside the oil seal, and when the plate is pulled up in the manner of leverage, the oil seal is also released. This tool was developed for replacing crankshaft seals and camshaft seals in automotive engines, so there is no guarantee that it will work for all output shaft and change shaft seals. However, if you can insert something through the gap between the shaft and the oil seal and pull it out, you can avoid the big job of disassembling the engine just for the oil seal.

But in some engines where the crankcase is divided into upper and lower parts, the ribs around the outer circumference of the oil seal are sandwiched between the cases to prevent them from coming loose, in which case it is not possible to remove just the seal, so, unfortunately, the crankcase must be disassembled.

As you can see, there are a number of different types of oil seals, and knowing that there are several different methods and tools for removing oil and grease leaks will allow you to take appropriate action without panicking when a problem occurs.