If your quad has drum brakes, check the brake engagement at least twice a year (you can't do it too much, so check it before every ride if you want). Put your machine up on a stand and spin the tires, then slowly engage the brakes until the wheels lock up. Did one wheel stop sooner than the other? If so, adjust the brakes individually so they stop evenly. There is an adjuster on each drum, and they are not self-adjusting like disc brakes. They can engage differently because they are cable actuated. Adjusting them will help you out in the event of an emergency stop, where uneven braking could cause your quad to react improperly.