If you're a lucky scooter owner, your front brakes use a drum system. However, most modern scooters have front disc brakes, which are a bit more complicated. Knowing how to repair either system is important for maintenance and safety.
Remove the front wheel rim on your scooter to access the brake system. Unbolt the rim from the wheel hub, loosening the nuts in a star pattern so that you don't warp the rim. Make sure not to untighten the rim nuts that keep the tire on, or it will burst in your face. The drum brake set-up will be concealed underneath the front wheel hub, so you will need to remove it. The disc brake will have a rotor connected to the front hub on the outside so, depending on the set-up, you can probably leave the hub alone.
Remove the circlips that keep the drum brake shoes on their pegs. Then remove the spring that keeps the shoes pressured together. Now you can wiggle the shoes off their pivot pegs and remove them completely. For a disc brake system, unbolt the caliper that holds the brake shoes on the rotor. Slip the caliper off the rotor so that you can access the shoes. You may need to drain the hydraulic brake fluid to replace the shoes, depending on your system.
Before removing the shoes on either system, check their wear. You may not need to replace them if sufficient shoe thickness still exists on a disc brake. However, brand new drum brake shoes are cheap and make a world of difference in stopping power. Throw out the old ones, making sure not to touch them directly, as most drum shoes are made with asbestos material.
Insert new drum brake shoes on the pegs in the inside of the front hub chamber. Use a very small bit of grease to lubricate the axis pegs so that the shoes can move easily. Then reinstall the spring holding the shoes together and install the safety circlips to keep the shoes in place. When reinstalling a disc brake, insert new shoes in the caliper, making sure to clean out any dirt and grit. Relocate the caliper onto the rotor and bolt it into place as it was previously. For both systems, then reinstall the front hub cover and front wheel.
Bleed the hydraulic brake system by adding new fluid to the reservoir chamber and letting it drain through the hose. When it flows completely as you pump the front brake lever, get ready to secure it to the caliper. When the brake pedal has pushed out all air in the hose and only fluid is coming out, it will feel stiff to press. Bolt the hose end to the caliper and close off the end of the hose in doing so. Then seal the reservoir at the handle, again making sure the hand brake pedal is stiff to press. If it is spongy, then the bleeding did not work; redo the bleeding process. Use gloves to keep the fluid off your hands.
Finish the drum brake system by connecting a new brake cable. Grease and run the brake cable and cable housing through the scooter from the headset to the front brake actuator arm on the backside of the front hub. Secure the cable end in the hand lever, and then run the other end through the actuator arm itself. Pinch the lower end of the cable with a securing nut after making the cable sufficiently tight. There should be no slack in the actuator arm or cable, or the front brake will not work well.
Have a clean, well-lit workspace to do the front brake repair job. Keep all your parts in a tray so that you don't lose an. Use new brake fluid for disc-brake systems and use a new cable for drum-brake systems. These items are cheap, and it's not worth trying to recycle old material.
When working with drum brakes, make sure not to breathe any of the drum shoe dust, as it very likely contains asbestos material. Always use plastic gloves and avoid touching your face while performing the repair. For disc brakes, do not leave your brake fluid exposed to air. It quickly inhibits the fluid's capability to work in the system. Keep the container sealed until you actually need the fluid. Also, make sure to use a DOT 3 or 4 grade brake fluid for scooter brake systems.