Meter gear connected to the speedometer. For drum brake Yamaha models, the point is to remove the gear bush.

Motorcycle speedometers today are mostly electric, but there are still many mechanical speedometers that transmit tire rotation to the meter via cables. For such a mechanical speedometer, it is important that the cable rotates smoothly and the condition of the meter gear on the wheel side. Here, we will introduce an example of mechanical speedometer maintenance by disassembling and cleaning the meter gear attached to the brake panel of the drum brake.

Different meter gears for drum brakes and disc brakes

Bushes removed from the brake panel and removal tools. This tool is an original product from a certain tool shop, but Yamaha genuine special tools are also on sale. It's a simple shape, but if you have this, you can easily remove the bush that is screwed deep into the brake panel. If you are a drum brake SR400 owner, the Yamaha genuine meter gear bushing tool is a dedicated tool that is worth having.

A pinion gear that changes the direction of rotation by 90 degrees in combination with a ring gear that rotates with the tire, and a bush with an oil seal at the tip. This bushing was used up until the 2000 model SR400, but going back, it was first used on the 50cc model YF1 released in 1964. Ring gears and pinion gears differ depending on the model, but Bush continued to use the same parts all the time.

The meter cable, which has long been used as a means of transmitting tire rotation to the speedometer, always functions as a set with the wheel (tire) side meter gear. The meter gear is a set of two gears, one that rotates with the wheel and the other gear that decelerates while changing the direction of rotation by 90 degrees, and is assembled to the wheel. And this meter gear has a different shape for drum brake vehicles and disc brake vehicles.

In the case of the drum brake introduced here, the two meter gears are attached to the brake panel, and the meter cable runs from the brake panel to the speedometer. On the other hand, disc brake vehicles generally have a meter gear installed in the center of the wheel in a special case.

This difference is due to the shape of the wheel hub. In the case of a typical drum brake, the hub to which the spokes and rims are attached and the brake panel (brake shoe plate) are two pieces, with the axle shaft running through the center. Therefore, a mechanism must be built into the hub or brake panel to extract the tire rotation. Therefore, a gear is attached to the brake panel attached to the front fork, and the rotation is picked up from the hub that rotates with the tire and transmitted to the brake cable.

Disc brakes, on the other hand, do not require a large hub at the center of the wheel, so only the meter gear is housed in a separate small case and attached externally to the center of the wheel hub. By the way, some racer replica models that take out the meter cable from the drive sprocket part also set the meter gear unit on the drive sprocket cover, and decelerate while converting the rotation of the output shaft by 90 degrees and transmit it to the meter. .

Purchase a genuine Yamaha meter gear bushing tool on Webike POINT

For drum brakes, the oil supply condition of the gear built into the brake panel is important

After removing the bushing and pinion gear from the brake panel, thoroughly with parts cleaner or washing oil. It goes without saying that you should remove the dirt from the inside of the brake panel, but if you don't remove the dirt from this part where the pinion gear fits, the dirt will stick to the meshing part of the pinion gear and ring gear.

The brake panel for AT90 in 1967 was equipped with a grease nipple to supply grease to the meter gear, and in the 1960s it was recognized as a lubrication point. The grease nipple was later abolished, but lubrication is still required.

In some older drum brake models, it may be better to perform maintenance on the meter gear part. Yamaha moped models manufactured in the 1960s and 1970s held the meter gear on the brake panel with a screw-in bush. As a remnant of this, the YB-1 of later years also adopted the same structure. Also, not only the moped class, but also the SR400 of the drum brake era uses the same bushes as those introduced here.

This type has an oil seal built into the end of the bush to prevent water from entering from the pinion shaft of the meter gear. However, there are cases where the oil seal deteriorates and no longer performs its sealing function after a long time has passed since its manufacture. Then, there is a possibility that water splashes when driving in the rain or rainwater transmitted through the meter cable enters the brake panel from the meter gear part. In addition, although a sufficient amount of grease is originally applied to the meter gear, it can be emulsified or washed away due to deterioration over time or water contamination.

This increases the friction loss between the two gears, which also leads to wear on the gears themselves. If the gears wear out due to lack of maintenance, the rotation of the tires will not be transmitted, causing trouble such as the speedometer not moving even though the meter gear is not cut. Meter cables often continue to be supplied as replacement parts even when the bike gets old, but meter gears are often discontinued unless they are used for multiple models.

In order to avoid such a situation, it is recommended to check the lubrication condition of the meter gear while removing the wheel and checking the remaining amount of brake shoes.

POINT

Old model Yamaha models require a special tool to remove the bushing

The plug at the tip of the meter cable that is inserted into the brake panel has an O-ring for dust and water resistance. ing. Even with this O-ring, dirt will get in over time, so even if it is broken, it should not be restored without the ring.

After inserting the meter cable, set the stop ring to prevent it from coming off. The same parts have been used for this ring from the early 1960s to the SR400.

As mentioned earlier, the bush that holds down the meter gear of the Yamaha moped class has a cross cut on the outer circumference, and a special tool is required to remove it. If the amount of screwing in the bushing is shallow, you may be able to use a slotted screwdriver instead of a chisel to turn it, but in reality it is not recommended as it may damage the insertion part of the meter cable.

If you just want to apply grease to the gear, you can do it from the inside of the brake panel, but you have to remove it to replace the oil seal that is pressed into the bush. Also, when polishing or repainting the brake panel during restoration, it is ideal to remove the meter gear and clean it by degreasing, so it is a good idea to remove the bushing that is screwed in.

Introduced here is an original product produced by a tool shop that looks like a deep socket cut with a grinder, but it is also sold by Yamaha as a manufacturer's genuine tool under the name Meter Gear Bush Tool. With this, you can take out the meter gear that is dramatically dirty with water and brake dust and clean it perfectly. In addition, if the bush is a single item, it is possible to replace the oil seal at the tip.

The meter gear on the drum brake panel may conjure up the image of a relic of the past that was exclusive to classic bikes, but once you learn that the SR400 uses this mechanism until 2000, some riders feel familiar with it. Isn't there?

Even if you have performed drum brake maintenance, you have never greased the meter gear attached to the same brake panel, or if the speedometer does not move even though the meter cable is not cut, We recommend checking the condition of your gear.

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