How to Change Drive Fluid on a Suzuki M109
Drive train or final drive fluid changes are an often-overlooked, yet crucial motorcycle maintenance task.
Changing the drive train fluid on a Suzuki motorcycle takes only a handful of minutes. Watch the video above and follow the step-by-step guide below to change the final drive fluid on a Suzuki Boulevard M109 motorcycle.
NOTE: This process applies to both Suzuki Boulevard and Suzuki Boss models.
Tools and Supplies – Suzuki M109R Rear Diff Fluid Change
Changing the Rear Differential Fluid on a Suzuki M109
Step 1. Get a drain pan ready, and remove the 21mm drain bolt on the rear differential.
Step 2. Replace the drain bolt once the fluid is completely drained, and torque it to 16.5 foot-pounds.
NOTE: This bolt has a crush washer that needs to be replaced if it’s damaged.
Step 3. Remove the 17mm fill bolt.
Step 4. Fill the rear diff with fresh 80W90 hypoid gear oil.
NOTE: Add about 7.4 ounces, which should be just about when fluid starts running out of the fill opening. You’ll know you’ve added enough when that happens.
Step 5. Wipe the excess fluid off and replace the fill bolt. Snug it down without overtightening it. Use contact cleaner to clean any overspill off of the motorcycle’s surfaces and you’re done.
NOTE: Wear safety glasses for this, since contact cleaner can harm your eyes.
The steps for changing the final drive fluid are the same or similar for all Suzuki motorcycles. However, if you want to see a final drive change on a similar Suzuki mode, watch the video above to see how to change the final drive oil in a Suzuki M90 Boulevard.