HD Primary Fluid Service TC 103

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HD Primary Fluid

Changing the fluid in your primary drive is a service point that will come up frequently in your Harley Davidson factory service schedule.

What About Clutch Adjustment?

The Twin Cooled 103 comes with a factory hydraulic clutch. This system eliminates clutch adjustment from your scheduled service. There is no adjustment to be made at the clutch pack and the clutch cable is now replaced with a hydraulic line; eliminating a cable adjustment. A quick inspection of your clutch master cylinder and line is all that is necessary. The dot 4 fluid should be clean (watch bleeding here) and at it’s correct level. The level should not vary, as this is a sealed system with no wear components to effect fluid level. See link to clutch adjustment.

Primary Chain Adjustment?

There is also no primary chain adjustment or inspection for a regular service. The primary chain is self adjusting. The primary adjuster shoe and primary chain can be inspected during high mileage repairs such as belt replacement, clutch replacement or primary / transmission seals replacement.

You will need to service the HD primary fluid.

You will begin your primary drive oil change by moving the passenger floorboard out of your way. Harley has now made this easier for us. Simply, remove the top bolt of the floorboard bracket and pivot the floorboard out of your way. Next, loosen and remove the derby cover hardware in a star pattern. Remove the derby cover and set it aside. Remove your drain plug and let the compartment drain completely.

Adding new HD Primary Fluid

You will prep your drain plug by discarding the old o-ring, cleaning the drain plug threads thoroughly. Then install a new, factory o-ring and thread sealant. With the drive completely drained, you can now reinstall the drain plug. Start it by hand. Then, snug and tighten 14 – 21 foot lbs. Now, fill the drive with 38 oz of premium primary oil. Do not overfill. The correct fluid level is vital for correct clutch function. Next, remove your old derby cover seal and replace with new. Correctly orientate your derby cover and begin all of the hardware by hand. Then, snug and final tighten in a specified pattern as Bob demonstrates. You will final tighten this hardware 84 – 108 inch lbs. Finally, re-position the passenger floorboard. Final tighten the securing bolt 36 – 42 foot lbs.

Changing your primary oil is a service point that will come up many times throughout the life of your motorcycle. Follow your specified torque specs and capacities. You will get the most possible longevity out of your primary drive/clutch assemblies.

Next Up: Spark Plugs