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Caring for your drivetrain: Final drive

Added September 14, 2020
Motorcycle drive train

Between every twist of the throttle and rumble of the motor, there are three steps your motorcycle takes to put that power to the asphalt. It starts with the primary drive, which transmits power from the motor to the transmission, and then the transmission turns the final drive to put the power to the rear tire. The final drive system is a critical—yet often forgotten—part of your motorcycle.

While modern motorcycles are marvelous machines that seem to be almost maintenance-free, the key word here is “almost.” All types of motorcycle final drive systems require you to perform routine inspections and maintenance to help ensure a long, trouble-free service life.

If your motorcycle's final drive system fails while you're riding, you could be left stranded. It could also lead to catastrophic damage, injury, and loss of life.

There are three common types of motorcycle final drive systems; chain drive, belt drive, and shaft drive. Let’s look at the three systems and their maintenance requirements:

Motorcycle chain drive maintenance

The chain drive is the most common motorcycle final drive system, offering great strength and power delivery, and easier changing of final drive ratios. Poorly maintained chains will deteriorate, reducing their efficiency until they finally fail from the stresses of delivering power to the rear wheel. When a chain fails under power, it locks up either the front or rear sprocket and wheel, which could lead to an unexpected skid and accident.

Maintaining a chain drive involves simple but routine pre-ride inspections.

Follow these four maintenance instructions:

1. Inspect the chain and sprockets

During your pre-ride tire inspections, check the chain and sprockets as you roll the motorcycle to see the whole tire. Compare your bike’s chain slack to your owner’s manual specifications to ensure it’s functioning properly. Your chain slack allows your motorcycle’s swing arm to move up and down over pavement irregularities while maintaining constant tension on both sprockets. Chain guards and covers may make it hard to see the front sprocket, so take your time to inspect your bike from different angles.

In addition to pre-ride visual inspections, be sure to inspect both of your sprockets, the chain, and chain slack whenever you’re performing scheduled maintenance near or directly on one of those areas.

2. Lubricate the chain

Lubricate your bike’s chain every 500 miles, using manufacturer-recommended products and techniques. Some chains have O-rings to keep lubricants inside of the moving parts, while other chains don’t and require different lubrication.

3. Clean and lubricate the chain and sprockets

Clean and then lubricate your motorcycle’s chain and sprockets every 3,000 to 5,000 miles. It’s a messy job, so it may make sense to schedule this maintenance to coincide with motor oil and filter changes.

Before cleaning, refer to your owner’s manual for approved chain cleaners, as some products could damage your motorcycle’s O-rings (if so equipped) and thus shorten chain life.

4. Adjust the chain

If you determine your bike’s chain slack needs adjustment, carefully study the owner’s or service manual before you perform the task. Adjusting the chain isn’t a difficult job, but it requires precision. Basically, you’ll need to move the rear wheel forward to loosen, or rearward to tighten the chain slack.

Some bike designs allow the rear axle to be moved within the swing arm. This requires you to loosen the axle nut and then retighten it to the correct torque.

It’s crucial that the rear wheel is straight in the swing arm once the chain adjustment is complete. A crooked rear wheel can quickly damage your motorcycle’s sprockets and chain—or injure you due to your motorcycle’s instability. If you’re in doubt about performing this maintenance, having your local motorcycle mechanic do the job is a good choice.

Motorcycle belt drive maintenance

Many manufacturers are opting to design their motorcycles with belt final drive. Belt drives are cleaner than chain drives and requires minimal inspection and adjustment. If you maintain a clean and properly adjusted belt drive, it can last up to 100,000 miles.

Your belt drive and both pulleys should be inspected every 3,000 to 5,000 miles, or along with your bike’s motor oil and filter changes. You should inspect both the inside and outside of the belt, and looks for chips, cuts, fraying, or missing teeth.

As is the case with a chain drive, proper slack is important, as it allows the swing arm to move up and down over pavement irregularities while maintaining constant tension (in this case on both pulleys rather than sprockets). Be sure you consult the owner’s or service manual for the slack specification, measuring technique, and point at which to take the measurement.

The slack adjustment for your bike’s belt drive is conceptually the same as the chain drive and therefore the same applies to wheel centering and axle nut torqueing (see chain drive section).

Motorcycle shaft drive maintenance

Shaft final drive is an entirely different drive system concept compared to chain or belt drives. When power exits the transmission of this system, it passes to the shaft, and the shaft drives your motorcycle’s rear wheel. The shaft is enclosed in an oil-filled housing or hub. You must replace the oil in the hub at the interval specified by your bike’s manufacturer.

These gears run in hypoid gear oil, which has a strong and distinct odor, so using oil-resistant gloves is a must. In addition to gloves, you’ll want to have a new O-ring and crush washer available to replace the old ones. Start by removing your bike’s drain bolt and then the filler bolt to allow drainage.

Your drain plug is magnetic, and is designed to capture any metal pieces from the housing as the oil drains. It’s normal to see small metal shavings collect here, but larger pieces of metal could indicate that your bike has issues that should be checked by a mechanic.

Once the oil is drained, clean your drain plug to remove metal shavings and then install the new O-ring with the drain plug to the proper torque. Now you’re ready to add the gear oil. Be sure to check your owner’s manual for your bike’s specified oil capacity. Have patience when filling, as this type of oil flows as slowly as molasses. Once you’re at capacity, install your filler bolt to complete this process.

On some shaft drive motorcycles, there’s a gear in the bike’s wheel hub and a corresponding gear outputting drive power from the final drive housing. These gears require greasing as well. Since that requires removing the wheel, you can do this when you replace your tires. If you ride in a lot of rain or dirt, or use high-pressure water when washing your motorcycle, you’ll need to grease these gears more often than the span of your rear tire’s life.

Caring for your drivetrain’s final drive is an important step in keeping your pride and joy rumbling as smoothly and safely as possible. After you’ve mastered this often forgotten maintenance and prepare to hit the open road, consider some of these amazing trips before you set out.

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