Cannot be removed with needle-nose pliers. Essential tool for snap ring removal and installation, the snap ring plier

When disassembling an engine or transmission, many people have likely seen ring-shaped parts set in shafts or holes. These are "snap rings." While not as prominent as bolts or nuts, they are important mechanical elements that hold components like bearings, gears, and piston pins in place. If even one is missing or deformed, it can lead to serious trouble. Snap ring pliers are the tools used to remove and install these crucial parts. Once you understand the features of these specialized tools, which are difficult to substitute with needle-nose pliers or pickup tools, you'll surely want them.

What are the characteristics of snap rings that allow for positioning and retention with a simple mechanism?

Snap rings are mechanical elements used to position and retain parts by fitting into ring grooves provided in various shafts and housings. They are made of elastic metal material, formed into a ring shape like a spring, and utilize their restoring force for fixation.

Since they do not require screw threads like bolts or nuts, they can ensure secure fixation even in limited spaces, making them adopted in many machines.

In motorcycles, they are used in various parts such as gears and shafts inside the transmission, bearings, clutch hubs, wheel bearing holders, and even in the oil seal areas of front forks.

For example, inside the transmission, multiple gears and collars are arranged on a shaft, and it is the snap rings that hold them in the correct axial positions. If the position of a gear shifts beyond its design tolerance, it can cause shifting problems, abnormal noises, or transmission damage.

If the snap ring holding the piston pin comes off, it can get caught between the piston and cylinder, causing severe damage to the engine.

Snap rings have the advantage of being lightweight and compact, providing high holding power without increasing the number of parts. They are a very rational fixing method in situations where vehicle weight reduction and miniaturization are required, but it is crucial that they are installed correctly in their designated locations.

There are two types of snap rings: internal and external

There are two types of snap rings: "internal" (for holes) and "external" (for shafts). Although they look similar, they are installed in different locations and have different functions, and they are not interchangeable. Therefore, they must be correctly distinguished during maintenance.

Internal snap rings are installed in "ring grooves provided on the inner diameter side" of parts like bearing housings and crankcase covers. When installing, the ring is compressed and pushed into the ring groove for fixation. They are often used to retain the outer rings of bearings and oil seals, and can be found in wheel hubs and crankcases.

On the other hand, external snap rings are the type installed in "ring grooves on the outer circumference of shafts." The ring is expanded and inserted onto the shaft, then fitted into the ring groove to prevent gears, sprockets, collars, etc., from moving axially.

They differ not only in installation direction but also in their cross-sectional shape and dimensions. Therefore, internal snap rings cannot be used on shafts, and external snap rings cannot be used in holes.

Specialized tool, snap ring pliers, are necessary for removing and installing snap rings

Internal snap ring pliers for removing and installing internal snap rings. The tips close when the grips are squeezed. Since the amount of compression required for removal and installation varies depending on the snap ring's diameter, some pliers indicate the compatible ring diameter. In the case of the wiha (Wiha) product shown, the small size supports φ12-25mm, and the large size supports φ19-60mm.

External snap ring pliers where the tips open when the grips are squeezed. Similar to internal types, the required opening width varies depending on the snap ring's diameter (shaft diameter), so several sizes may be available. The small size supports φ10-25mm, and the large size supports φ19-60mm.

When removing and installing snap rings for maintenance or repair, specialized tools are required. While skillful individuals might be able to substitute with needle-nose pliers or pick tools, it can also damage the snap rings or surrounding parts. Therefore, for work efficiency and safety, it is safer to use specialized tools.

Common snap rings have small holes in their opening. The tips of snap ring pliers are shaped like pins, which are inserted into these holes to open and close the rings. The tool securely holds the ring, allowing for removal and installation without deforming it excessively.

Just as there are internal and external snap rings, there are also internal and external snap ring pliers. Internal pliers have a structure where the tips close when the grips are squeezed, and the ring is compressed for installation. The action of the tips closing when the grips are squeezed is the same as with general pliers.

In contrast, external pliers have a structure where the tips open when the grips are squeezed, and the ring is expanded for work.

In other words, the movement of the tips when squeezing the grips is the opposite for internal and external types, making them incompatible. Therefore, when purchasing snap ring pliers, you need to have both internal and external types.

Some snap ring pliers can handle both internal and external types by reconfiguring the pivot part. Additionally, besides straight types, there are also bent types with tips angled at 45 or 90 degrees. These make it easier to access recessed areas or areas with obstructions, and may be essential depending on the vehicle model.

Reasons to use snap ring pliers instead of pick tools or needle-nose pliers

The tips of wiha snap ring pliers are of the separate pin press-fit type, with the pins for external use slightly angled outwards and the pins for internal use slightly angled inwards. Furthermore, by grinding the outer surface for external types and the inner surface for internal types, they prevent slipping from the snap ring's hole and ensure the pins do not easily come out when the grips are squeezed. These details vary greatly among tool manufacturers, so it is important to check carefully when purchasing.

Example of using internal snap ring pliers. Depending on the depth of the hole and the shape of the part inserted into the hole, the straight tip may not reach. Therefore, simply owning one pair does not guarantee success; it may be necessary to use multiple pliers with different compatible ring sizes, tip lengths, and shapes.

Example of using external snap ring pliers. When lifting from the groove, over-expanding can not only reduce tension but also cause the ring to twist, leading to it popping out of the groove during re-use. This would prevent proper gear positioning, so it is advisable to use specialized tools to avoid damage.

It might seem burdensome for DIY mechanics to prepare multiple snap ring pliers, considering there are internal and external types, plus different tip angles.

As mentioned earlier, snap rings can sometimes be removed with needle-nose pliers or pick tools. However, this is merely a temporary measure and not a recommended work method.

Needle-nose pliers have tip shapes that are not specifically designed for snap rings, so they may not fit into the holes on the ends, and cannot hold the ring evenly. Uneven force can cause the ring to twist or scratch the groove. Holding small rings can be unstable, and there is a risk of them suddenly coming off and scattering.

Working with pick tools, which have sharper tips than needle-nose pliers, involves prying the ring off. This method carries a high risk of scratching the ring groove, and if the tool slips, the worker could be injured.

Furthermore, snap rings are weak against repeated deformation, and applying excessive force can reduce their holding power. Over-expanding an external ring can increase play in the ring groove, affecting its intended purpose of positioning gears and collars.

Snap ring pliers, with their tips holding the ring and opening/closing it evenly, allow for secure work while preventing deformation and scattering. Considering part protection, safety, and work efficiency, using specialized tools is the best choice.

Conversely, if you hesitate to purchase snap ring pliers, it is better to decide not to perform maintenance or repairs on parts involving snap rings. It is wiser not to attempt the work at all if you risk exacerbating damage by forcing it with substitute tools.

Nevertheless, if you want to expand your motorcycle tinkering capabilities, we still recommend purchasing snap ring pliers.

There are also specialized pliers for snap rings without holes and for piston pin clips

Specialized straight-brand pliers designed for removing and installing hole-less locking rings set on shafts.

The tips, which open when the grips are squeezed, are flat surfaces with anti-slip processing, acting to push and expand the ends of the locking ring.

Locking rings are often used on transmission shafts, and specialized pliers significantly improve the efficiency of removal and installation work.

Straight-brand piston pin circlip pliers specialized for removing and installing piston pin clips. While general needle-nose pliers are around 160mm in total length, these pliers are smaller at 130mm, with thin, upward-curving tips.

One side of the gripping part has a groove for clamping the clip, while the other side has anti-slip serrations.

By gripping the clip with the groove on the gripping part, it will not fly off and get lost during removal. When setting the clip in the groove during engine assembly, it can be securely installed in the narrow groove.

Most snap rings, whether internal or external, have small holes at their opening. However, some external snap rings are of a type without holes.

The advantage of hole-less types is that the cross-section of the entire ring can be made uniform. Since there are no holes, there is less stress concentration, making them advantageous in terms of strength and durability. Therefore, they are sometimes used in machines subjected to high loads or in high-speed rotating parts.

Hole-less types, also called locking rings, do not have holes for pliers at their opening, so they cannot be removed with general snap ring pliers. Therefore, pliers that open at the tips when the grips are squeezed and can evenly expand hole-less rings make the work proceed smoothly.

There are also specialized pliers suitable for preventing the loss of piston pin clips, a common mistake during engine maintenance. The tips of these pliers are sharp and processed to securely hold thin piston pin clips, making them a type of specialized tool that is rarely used for anything other than piston-related work. Like snap rings, some people may remove piston pin clips with precision screwdrivers or pickup tools.

However, if you excessively compress a piston pin clip during removal, its tension will decrease, making it more likely to come out of the ring groove. This carries the risk of significant damage to the cylinder and piston after assembly. If you have new clips ready for installation, it's fine if the removed clips get crushed, but if you intend to reuse them, it's best to use tools that allow for removal without damage.