The sealed chain, in which grease is sealed in advance in the gap between the bushing and the pin, features low friction loss and long life. However, a special riveting tool is required to connect the joints, which is a hindrance for DIY maintenance. The EK CHAIN screw joint eliminates this issue, and its greatest feature is that the sealed chain can be assembled using only common hand tools.
- Sealed chains are far superior in terms of dynamic performance
- Riveted joint required to maintain seal ring clearance.
- Screw joint that press-fits the outer plate with a special nut
Sealed chains are far superior in terms of dynamic performance
The SRX series of EK sealed chains features a well balanced design that can be used in a wide range of situations. The size lineup includes 420/428/520/525/530, of which screw joints are available as an option for 520/525/530 sizes. When purchased as a packaged item, a standard rivet joint is included.
There are 2 types of motorcycle drive chains: non-sealed chains and sealed chains. The structure of the chain is the same whether it is for bicycles or motorcycles. The chain rotates by flexing as the pin, which is press-fitted into the outer plate, passes through the bushing, which is press-fitted into the inner plate.
The sealed type is filled with grease between the pin and the bushing, and this grease reduces the friction loss between the pin and the bushing. Also, by not having the pins and bushings rubbing directly against each other, wear is reduced and the life of the chain itself is extended.
Since the pins and bushings of a non-sealed chain are in direct contact with each other, lubrication with chain oil is indispensable. If the chain is driven without maintenance, regardless of rain or wind, the clearance between the pins and bushings will increase due to wear, and this will cause the chain to stretch. Some riders may hear that the chain stretches and understand that the small oval plate stretches, but the actual stretching is caused by the wear of the pins and bushings, not by the plate being stretched.
The first sealed chain was developed in 1974 by Enuma Chain Manufacturing, known under the brand name of EK CHAIN. It was at this time that a rubber seal ring was incorporated into the gap between the inner and outer plates to prevent grease from flowing out of the gaps between the pins and bushings.
The seal ring used in the first sealed chains was a simple O-ring with a circular cross-section, which sealed the grease by being squashed between the plates. Eventually, various innovations were added to the cross-sectional shape of the ring to reduce friction and extend the life of the seal itself due to wear.
Even nowadays, there are rare riders who turn the rear wheel by hand while it is floating on a stand and think that a non-sealed chain turns more lightly than a sealed chain and therefore has less friction loss. However, in actual riding, where the driving force is much greater than in hand-cranking, the grease filled sealed chain offers much less resistance.
Also, some users say that chain lubrication is unnecessary because the sealed chain is greased, but the roller part of the chain that contacts the sprocket is not greased, so it needs to be oiled periodically. Using a chain cleaner before spraying a chain lube is also effective in cleaning sand and dust from the chain and sprockets to prevent excessive wear.
- Point 1: A sealed chain, in which grease is sealed in the gap between the pin and the bushing, has less friction loss than a non-sealed chain.
- Point 2: Even with a sealed chain, periodic cleaning and lubrication of the meshing part between the sprocket and chain is necessary.
Riveted joint required to maintain seal ring clearance.
Enuma Chain Tool CRT50A can be used for cutting, press fitting of joint plates and riveting of joint pins when adjusting the number of frames in a chain. This tool was developed by the chain manufacturer itself with a focus on safety, functionality, and workability, and is extremely easy to use. The compatible chain sizes are 415/420/428/520/525/530/532. The 630 requires parts sold separately.
The tool itself is sturdy, and the amount of press fit of the outer plate and the amount of riveting of the pin, which are key to the work, are easy to understand. However, the manufacturer’s suggested retail price is 350 USD (tax included), so the price may be a concern for the average user who uses it infrequently.
Sealed chains, which are superior to non-sealed chains in terms of performance, are commonly installed in production vehicles of small models and above. Or, even if the OEM chain is non-sealed, many users choose to use a sealed chain when replacing it.
If you compare a sealed chain and a non-sealed chain of the same size and number of links, the sealed chain is more expensive. This is because seals and greases are utilized in the sealed chain that are not used in the non-sealed chain. However, the durability is improved due to less wear on the pins and bushings, and according to manufacturer’s tests, the life of a sealed chain can be 10 to 20 times longer. Since there is no 10-fold difference in price, sealed chains are more cost-effective.
However, for DIY maintainers, the special tools required to replace the seal chain are a bottleneck. For a non-sealed chain, once the outer plate of the joint is set, it can be clipped in place and connected, but for a sealed chain, the joint plate must be press-fitted and the head of the pin must be riveted to widen it.
The reason for this is to ensure the correct performance of the sealing ring that contains the grease. A proper clearance is set for the seal ring, which seals the grease sealed in the gap between the pin and the bushing, and also catches the friction generated by the plates rubbing against each other. If the plate is not pressed in enough, the sealing force will be insufficient and grease may leak out.
On the other hand, if the plate is pressed in too far, the seal will be crushed too much and broken by friction, which will also cause grease leakage. Furthermore, if the fit between the joint pin and the outer plate is loose, as in the case of a clip joint in a non-sealed chain, the plate may move and the pressure applied to the seal ring may increase or decrease.
For this reason, the sealed chain joint requires the outer plate to be press-fitted against the pin to the proper position, and the pin tip to be riveted and pushed open to prevent it from coming loose. To do this, a special chain tool capable of press-fitting and riveting is an essential item.
Needless to say, the drive chain is a safety-critical component. In particular, the joint work of sealed chains, which are also used in large vehicles with large displacements, is very important, and chain tools must be well made. Enuma Chain Manufacturing, a pioneer in the field of sealed chains, offers its own special tool, CRT50A modified, but it is an expensive tool with a suggested retail price of nearly 350 USD. This is why the quality of the work is high and reliable, but it is not a light burden for users who tinker with motorcycles as a hobby. For this reason, many users of sealed chains ask motorcycle stores to replace them.
- Point 1: Sealed chain joints are generally made by press fitting a plate and riveting the pin head.
- Point 2: Reliable joint riveting tools are not inexpensive, which is a barrier for DIY maintenance users.
Screw joint that press-fits the outer plate with a special nut
The EK CHAIN’s unique screw joint is an optional parts for the Enuma Chain Manufacturing’s specific chains, and its greatest feature is that the outer plate can be press-fitted without special tools. This is ideal for users who want to install the sealed chain by themselves but are not willing to buy a special tool.
After applying special grease to the joint pin and the inside of the bush, tighten the nut and press-fit the outer plate onto the pin. The working procedure is also easy to understand: tighten until the pin touches the bottom of the nut, and the plate will be press-fitted to the proper position. After the plate has been press-fitted, loosen the nut to the nub in the middle of the male thread, and fold it away with the nut.
The screw-type joint, an optional part originally developed by Enuma Chain Manufacturing, overturns this common practice when installing sealed chains. The screw joint, with its unique male threaded joint pin at the tip, screws in the outer plate with the supplied nut. Due to the difference between the outer diameter of the pin and the inner diameter of the outer plate hole, the outer plate is press-fitted into the pin when it is screwed in, and the plate will not come off.
The included nut has a stop hole and is designed so that the amount of press-fit of the plate is correct when it is turned until it hits the male screw on the pin end, so there is no variation no matter who is doing the work. After screwing in the nut, the joint can be finished by folding off the threaded part, and there is no need to crimp the head of the pin.
This joint is only available for EK CHAIN, and is a separate parts that can only be used with certain EK sealed chains (SRX2 and ZVX3 series in sizes 520/525/530). However, for some users, these parts for DIYers will be the motivation to choose this chain.
Although special tools are basically required to replace the seal chain, it may be useful to know that some of them can be jointed using only hand tools, which may be useful for driveline maintenance.
- Point 1: Enuma Chain’s screw joint can be used to joint the sealed chain using only universal tools.
- Point 2: Screw joints available as optional parts can be used with a limited number of products in the EK CHAIN.
See Accessories of EK CHAIN