Drum brakes, like those found on most cars, used to be the principle method of slowing down a motorcycle. Since the 1970s, most manufacturers have shifted to the disc brake, as it is more powerful and reliable. Drum brakes still appear on smaller motorcycles and mopeds, however, as the lower weight of the vehicle puts less strain on the brake, making it less susceptible to the overheating and wear-outs that led to drums being removed from larger machines.
Instructions
- 1
Examine the linings of the brake shoes. One of the main problems with drum brakes is the high speed at which they wear. If you've noticed a sudden drop-off in braking force, remove the drum and check the shoe linings for wear. If they are excessively worn, they will need to be replaced with new ones. Linings for modern brakes are available at ordinary service centers, but if your machine is a classic, there may be an issue. The original brake shoes on many older bikes contained asbestos, to control temperature. As this is now a restricted material, it will be necessary to source replica linings made from modern materials. It will be necessary to contact a motorcycle restoration specialist to have the shoes re-lined.
2Check the surface and overall shape of the drum. It should be perfectly round, not dented or distorted in any way. If the drum is warped, the brakes will not maintain even pressure as the wheel rotates, which can manifest itself as squealing or juddering under braking. Materials that radiate heat well make the best drums. Cast iron, rolled steel or aluminum are ideal. If the drum gets too hot, it will expand, reducing the pressure on the shoes inside, which in turn reduces braking pressure.
3Remove the shoes and examine the cam levers that press on the shoes when the lever is pulled. Check them for bends or warping as this would reduce the pressure they exert on the brake shoes. They can be replaced with longer versions to increase braking power, as with all physical levers, a longer lever can exert more force.
4Check and air vents on the drum are clear and allowing the free movement of cool air through the drum. Overheating is the worst enemy of drum brakes, so keeping them as cool as possible will preserve their power. Once you've taken the drum apart and familiarized yourself with the locations of all the mechanisms inside, it can help to drill a few small holes in the trailing edge of the brake plate, allowing hot air to exit more effectively.
