Rear Harley brake fluid level can be inspected by viewing the fluid level through the rear master cylinder reservoir sight glass.
However, when performing a major scheduled service, it is important that the reservoir top cap is removed. This allows for a better view of both the fluid level and the fluid condition.
On most major services the Harley brake fluid will be flushed, replenished, and the system bled. At these services, it is still important to get a clear view of the brake fluid conditions. It can help you to determine the beginnings of a possible fluid leak or even excessive master cylinder wear. The rear master cylinder reservoir is located near the rear foot brake pedal.
The top cover is secured with two Phillips head screws. It is easiest to access these screws using a phillips screwdriver that has a longer than standard shank. As usual, use caution when removing the top cap and top cap seal. DOT 4 Harley brake fluid can be damaging to painted, plastic, or leather surfaces. If DOT 4 brake fluid does find its way onto a finished surface, there is no need to panic but don’t wait too long to clean up. Wipe it away thoroughly with a clean cloth and a mild glass cleaner. In fact, it is a good idea to have your cleaning supplies out and nearby before you are to open any components that hold or contain DOT 4 brake fluid.
If the top cover gasket is damaged or warped, it is important that it is replaced. DOT 4 brake fluid is very susceptible to moisture. If the brake system is not completely sealed, the Harley brake fluid will break down and will become damaging to components like the ABS modulator, the master cylinder, and calipers.
Remember, the Harley brake fluid level in the reservoir will decrease with brake pad wear. Fluid should never need to be added or removed from the system during normal wear. Reservoir volume is adequate to provide fluid to the wear limits of the pads and rotors.