Dax’s Suspension Maintenance Challenge | The Condition of the Front Fork Changes the Riding Drastically!

If it's not out of gas, it's still fine to ride. I change my engine oil regularly, so it's not a problem, and it's a two-stroke engine, so it's not a problem. I never forget to put in engine oil for separate fueling, so it's okay, etc. If you only pay attention to the condition of the engine, the "good condition" = "good period" will be over in no time. It is only when you take care of various parts that you can truly maintain your motorcycle and keep it in great shape. For this reason, daily inspections are also essential. Let's take on the challenge of maintaining the front forks of the Honda Dax, which was found to be leaking oil.

Oil seals are surprisingly out of stock at the manufacturer

When you notice that you have an oil leak, don't just start disassembling. When you notice an oil leak, don't just start disassembling. Think about "replacement parts", "parts that will be replaced", and "parts that you want to replace in addition", check the manufacturer's inventory and estimate, and secure the parts before proceeding with the work. Check the manufacturer's stock and quotation, and secure the parts before proceeding with the work. Only two front fork oil seals were replaced here. If Honda's genuine parts are out of stock (discontinued), you can look for the same size parts that can be used among the genuine parts of other models, find compatible parts among the oil seals for front forks made by other manufacturers, or, as a last resort, find the same size parts among the standard oil seals for general industrial use. There are several ways to do this.

Let's touch the bottom case with our fingertips once in a while.

I'm sure many riders have had the experience of looking down at their feet after the engine has warmed up and finding a puddle of oil under the engine. It's the same with the front forks. The same is true for the front fork. When I was out on the road, I casually touched the bottom of the front axle shaft with my fingertip and found oil all over it. When I looked under the front wheel after I came home, I found oil dripping from the bottom case. So this time, I checked the parts list, bought the suitable oil seal, and disassembled the front fork after securing the parts. This type of front fork for Dax (Dax Sports) was the "outer spring type" where the fork spring is set between the fork cover and inner tube.

Divert flywheel holder with a rubber band

The oil seal of the Sport Dax is built into the bottom case, but a plated cover is set near the oil seal holder, so the work cannot proceed without removing the cover. But the cover is rusted? The cover was rusted or stuck, so it did not work at all. So I used a rubber band type flywheel holder (bought a long time ago) to remove the chrome cover without scratching it. This is a completely different application, but it is useful to have various special tools in such a situation.

The iron circlip that holds the oil seal in place is prone to rust. It is thought that the rust of this circlip bit into the oil seal lip and damaged the oil seal. If this condition is left untreated, all of the fork oil will drain out and the inner and outer tubes, including the rust, may become crazed. I want to repair it as soon as possible to avoid worsening the affected symptoms.

Dove-smelling fork oil lacks change history

Inside the front fork is suspension oil. Generally, the oil viscosity for upright forks is around #10. Kayaba fork oil is G10 and Showa fork oil is SS-8. By changing the hardness of this fork oil (for example, from standard No. 10 to No. 15 or No. 20) or changing the amount of oil, you can find your favorite setting. The setting data of the amount of oil and oil level height indicated by the manufacturer should be considered as a standard value only.

Disassembly is also available for structures without a seat pipe

Since the inner seat pipe is not tightened at the bottom of the bottom case of the Sportsdax, you can remove the circlip that holds the oil seal, fix the bottom case in a vise, and pull out the inner tube forcefully. The inner tube can be pulled out. After pulling out the inner tube, check it carefully to see if it has any rust spots or insect-eating rust. Let's check it carefully.

Rubber grease for oil seals

There are various tips and techniques for inserting the oil seal into the inner tube. As a minimum, rubber grease should be applied to both the oil seal lip and the inner tube end face. The rubber grease reduces the sliding resistance between the metal and rubber parts. The general MP grease (*Note: MP = multi-purpose, used in a wide range of situations, such as urea grease) and molybdenum disulfide grease, which is used for extreme pressure parts between metals, are not used for oil seal installation.

Insert the lip without scratching it.

The most important thing is to assemble the oil seal without damaging it. There is a technique to apply rubber grease to the oil seal, then press one side of the seal lip against the inner tube at a slight angle, then slide the other side in. Another method is to cut a thin plastic bag, cover the end of the inner tube, insert the oil seal, and then remove the plastic bag. Let's assemble it carefully and flexibly.

Hook the threaded rod and pull up the inner

In the case of a motorcycle with an outer spring, it is difficult to push the inner tube up to the tob bridge when restoring the motorcycle. Normally, there is a special tool that matches the diameter and pitch of the thread, but it is not always easy to find. In such cases, you can use threaded rods available at home centers. Even though the thread diameter is the same, the thread pitch is different, so it is best to turn the end of the threaded rod lightly so that it catches on the inner tube (to avoid damaging the inner tube thread), and then lift up the inner tube. After lifting up to the top bridge area, temporarily fix the stem side clamp, and when the top bolt thread is correctly screwed into the inner tube, loosen the stem side clamp and tighten the top bolt firmly. Finally, tighten the stem clamp again to the standard torque.

Let's check the stroke after assembly.

Let's fill the amount of fork oil according to each model, based on the data in the manufacturer's genuine service manual. In general, the "oil capacity" setting is used for small-displacement models, while the "oil level height" setting is used for mid-sized models and above. After assembly is complete, hold the brake lever and fully stroke the front forks several times to check operation. If too much oil is injected, the air chamber in the inner tube will be lost and the fork will not operate at all, resulting in an "oil lock" condition. Start by filling the fork with the specified amount of oil, and as you ride along you will notice that even the slightest change in the setting will make a noticeable difference in operation.

When it comes to the front forks of the Dax and Monkey, most of them are inverted, like a soft motorcycle without an oil damper. However, there was also a model in the Dax series called the "Sport Dax" that pursued a more authentic, sporty riding style. This sport version had a full-fledged telescopic upright fork with a built-in oil damper. This Dax is the exact model. However, the bottom case was dripping with oil and after parking the motorcycle, there was a puddle of oil under the bottom case.

Before starting the work, I checked the manufacturer's stock of genuine parts. It seems to be used in other models, and the parts were delivered as the part number in the parts list, not the discontinued. I was relieved that I could get the replacement parts, but since I was going to disassemble the motorcycle, I might as well replace the peripheral parts with new parts. In this case, since the front wheel was removed, the wheel hub bearing was the part to be replaced. If the brake shoes were worn out, the shoes should also be replaced. However, in the case of this Dax, when the wheel rim was replaced with a wide aluminum rim, the wheel hub and the cross-shaped spokes were repainted with a two-component urethane can spray, and the bearings were already replaced with new parts at that time. Actually, I was wondering if I should replace the front fork oil seal when I did that. I was worried about it, but if the oil started to leak after riding, I can do additional maintenance! But I thought it would be better to replace the oil seal if it started to leak.

Before removing the oil seal from the front fork, it was difficult to remove the cosmetic cover of the chrome tube, but by using the rubber band type flywheel holder (special tool), it could be removed smoothly. The oil seal was removed using snap ring pliers, but this snap ring was rusty and red, so I used a metal brush to remove the rust and painted it with rust inhibitor before reusing it.

The assembled front fork is difficult to incorporate due to the rebound of the outer spring, but in such a case, it is best to use a threaded rod that can be purchased at any home center and pull it up without damaging the threads on the inner tube side. After the work was done, there was no more oil leak and the driver can concentrate on driving.

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