Change The Transmission Fluid In A Harley

As one of the three fluids that are crucial to a Harley-Davidson motorcycle’s operation, the transmission fluid lubricates the assembly of gears that transmits the motor’s power to the rear wheel. Much like the oil used by the machine’s motor, the oil within the transmission will begin to thin over time. If left unchecked, the thinned fluid begins to lose its ability to lubricate and cool the transmission, creating excessive wear that could cause permanent damage. Replacing the transmission fluid regularly can prevent this from happening. In fact, Harley-Davidson recommends changing the fluid every 2,500 miles.


1. Unscrew the filler cap from the right side of the transmission assembly.

2. Look under the transmission assembly to find the drain plug. Place an oil pan directly below the plug.

3. Use a 5/8″ socket and a socket wrench to unscrew the drain plug bolt. Drain the transmission fluid into the oil pan.

4. Pull the sealing washer off of the drain plug and replace it with a new sealing washer. Screw the drain plug into the transmission assembly by hand. Use a toque wrench to tighten drain plug to 21 ft-lbs.

5. Use a funnel to pour up to a quart of Harley-Davidson transmission fluid into the transmission assembly.

6. Screw the filler cap onto the transmission assembly.