There are two types of drive chains: non-seal type and seal type, and most seal chain joints use a crimped fixation.
When replacing a seal chain as a DIY project, a chain tool is required to clamp the pins, but before that, there is the process of press-fitting the outer plate of the joint. This process may seem simple, but there is an important point to be considered.
Seal chain replacement begins by pushing out the press-fit pin.
Seal chains installed on new vehicles are often assembled without joints, and the shape of the pin head is the same all the way around, so it does not matter where the pin is cut. Before pushing it out with the cutting attachment of the chain tool, it is recommended to shave the head of the pin with a disk grinder to reduce the load on the tool.
The severed chain is not immediately removed, but can be continuously installed by connecting a new chain with a tying band and then pulling it out. When drive sprocket replacement is not necessary, this method can be used to stretch a new chain without needlessly getting hands dirty.
It is not easy to hang a winding chain on the drive sprocket on either on-road or off-road models, and keeping fingers close to the sprocket can cause an accident. It is recommended to connect the old and new chains together for safe operation. However, if the inside of the sprocket cover is soggy and dirty with chain lube, mud, or gravel, it must be cleaned before installing the new chain.
Seal chains, which have low friction loss and good wear resistance when running, are installed on many motorcycles regardless of whether they are on- or off-road models. Although they have a longer life than non-seal types in terms of elongation, gradual elongation is inevitable due to repeated strong pulling by the driving force and engine brake.
When the time comes to replace the chain, the procedure and tools required are completely different for sealed and non-seal chains. In the case of a non-seal chain, the two ends of the chain are often connected by clip joints, and the retaining clips can be easily removed with pliers. The outer plate of the joint held by the clip can also be removed with pliers or fingertips because the clearance with the joint pin is reasonably loose. Therefore, a new chain can be installed with a finger or pliers.
In contrast, the work on a seal chain is different, starting with the stage of removing the old chain that has been stretched. The joint of a seal chain is called a crimped joint, and the pins of the joint, like other pins, are crushed at both ends by strong pressure and spread out to prevent them from coming loose. In some seal chains installed on new vehicles, all the pins are crimped in the same shape all the way around, and it is difficult to tell where the joint is.
Even in a non-seal chain, pins other than those at the joints are clamped, but the reason why the seal chain is clamped to the pins at the joints is to retain the grease applied between the pins and bushings. If the pin and outer plate are movable, as in a non-seal chain, the pressure applied to the oil seal incorporated between the inner and outer plates fluctuates, and the grease inside the seal cannot continue to be sealed. Therefore, the outer plate is press-fitted against the pin and secured by tightening the outer end of the plate. This is why the seal chain is tightened in the same way all the way around the pin when installed in a new motorcycle.
For this reason, when replacing an old seal chain, even if the head of the pin that is welded to the outer plate is shaved off with a disk grinder, the pin is press-fit into the plate and cannot be easily removed with pliers, etc. The pin must be pushed out with a special chain tool. The resistance to pushing out the joint pin with a chain tool is greater than expected, and inexpensive tools may lose the threads on the tool side. Even when using a reliable tool, it is effective to take precautions such as shaving the head of the pin with a grinder to reduce the load and applying molybdenum disulfide grease with excellent extreme pressure properties to the threaded part.
The chain itself can be removed by cutting it with a grinder, but considering the work involved in installing a new chain, a special tool is necessary. Due to the nature of the part, it is best not to think of using only general-purpose tools.
POINT
Point 1 - The joint plate of a non-seal chain can be easily removed, but a seal chain requires a chain tool for cutting because the plate and pin are press-fitted together.
It is essential to check the amount of press-fit when installing the outer plate of the swaged joint.
The grease included with the seal chain should be applied to the joint pins as a matter of course, but also to the seal ring contact area. You can also put grease on your fingertip and rub the seal. It is also important to apply grease to the entire circumference of the pin because if grease is applied to a single spot on the pin, it will be scraped off when the pin is threaded into the bushing.
Connect the two ends of the chain with the joint, set the plate on the pin, lightly pinch it into position with pliers, etc., and slowly press it in with the plate press-fit attachment. This tool is safe because the pin on the opposite side has a retaining clip, but be careful not to press-fit the plate on the press-fit side at an angle, as it may come loose on the opposite side.
It is better to repeat the plate press-fit and check the amount of press-fit too many times to be too careful. If you press-fit the plate all at once, thinking it is still OK, and it becomes narrower than the adjacent link, you are out of luck.
A joint that has been press-fitted too tightly will move more slowly than other links.
If the amount of joint press fit is correct, the head of the pin is crushed and clamped. The amount of caulking may be measured by the diameter of the crushed head, and some chain tools come with a gauge that can measure the amount of caulking.
The most important point when assembling a crimped joint using a chain tool is, by far, the crimping of the pins.
If the amount of clamping is too little, the outer plate may come off, and if too much, the tip of the pin may break.
However, there is an even more important operation before the crimping process. This is the press-fitting of the outer plate. As explained earlier, the outer plate of a sealed chain cannot be inserted with fingers or pliers as in the case of a non-seal but must be pressed in with the press-fit attachment of the chain tool. The amount of press-fit of the outer plate to the link pin can be set as desired, but maximum care must be taken because the amount of press-fit will increase or decrease the friction at the joint and also affect the life of the seal.
If the amount of press-fitting of the plate against the pin is shallow, the pin head will protrude less, and the pin head will be less collapsed when it is tightened, resulting in a failure of the locking effect, and furthermore, not enough pressure is applied to the seal ring that seals the grease applied to the pin, which may cause grease leakage.
On the other hand, if the outer plate is press-fitted too tightly, the seal ring may be excessively crushed and damaged, and this may lead to increased friction loss at the joint. If the seal ring breaks, grease leaks, and friction is increased only at the joints, the replaced chain will not be able to reach its full potential.
To determine the correct amount of joint plate press-fit, it is known to measure the outside width of the links outside the joint and match it, or to use a scale to match the width of the links on both sides of the joint. Some chain tools have a plate press-fit attachment that touches the plates at both ends of the joint, and when it touches the plate, it increases the resistance during press-fitting to determine the correct amount.
The method using a scale is shown here. The measurement is repeated many times, and the joint is press-fitted until there is no gap between the joint and the adjacent link. If the press-fit tool is over-tightened and the joint becomes too narrow, it is basically impossible to start over, and the pin must be pushed out, the joint discarded, and a new joint started over.
When press-fitting joint plates, press them straight into the pins so that they do not lean against the pins, and assemble them with the proper amount of press-fitting to ensure correct pin crimping in the final process.
