Improper design of brake drum, which is changeable when heated; Brake drum force is not balanced, will also produce mechanical deformation, so that the hooves and drum contact is poor, resulting in pedal force and stroke increase; When the unroundness of the working surface of the brake drum is too large, it will also cause self-locking and vibration and noise. Therefore, the brake drum should have sufficient wall thickness, and cast circumferential or axial stiffeners near the opening on the outer surface to improve the strength. These reinforcing bars also play the role of heat dissipation, can reduce the temperature of the friction surface, shorten the cooling time of the brake, and increase the energy capacity by 35%~40%.

The working face of brake drum is generally assembled with the hub and finished by positioning the bearing hole. The miniature car requires the roundness and coaxiality tolerance of the working face ≤0.03mm, the radial runout ≤0.05mm, the static unbalance ≤1.5N·cm.