Don’t over tighten the drain plug.
While most motorcyclists are well-versed in the proper method to replace their machine’s motor oil, Harley-Davidson riders must also replace a separate fluid that lubricates their motorcycle’s transmission. This can cause some confusion for newer owners of Milwaukee’s finest motorcycles, since most manufacturers consolidate their motor and transmission into one single unit. Luckily, changing the transmission fluid is a simple task that doesn’t require special knowledge.
1. Unscrew the filler cap from the right side of the transmission. Locate the drain plug on the bottom of the transmission and place an oil pan directly beneath it.
2. Unscrew the drain plug using a socket wrench and allow the transmission fluid to drain completely.
3. Remove the O-ring from the drain plug and wipe away any debris or buildup with a shop towel. Slip a new O-ring onto the drain plug. Insert the drain plug into the transmission and tighten it with a socket wrench. Wipe away any remaining fluid from the bottom of the transmission with a shop towel.
4. Insert a funnel into the filler neck on the right side of the transmission. Add up to one quart of fresh transmission fluid. Remove the funnel and wipe away any transmission fluid that may have spilled with a shop towel. Screw the filler cap onto the filler neck.