What Causes the Abnormal Noise in Scooters?

[DeFelix]

Scooters may produce abnormal noise due to the following reasons: 1. Piston issues: If the piston gets stuck, the brake shoes and disc may not separate completely, leading to a "squeaking" friction noise. 2. Worn brake shoes: If the brake shoes are worn (including uneven wear, which could also be caused by the aforementioned piston issue), the friction surface edges may expose metal, resulting in abnormal noise when rubbing against the disc. 3. Uneven disc surface: If the disc shows obvious concentric groove marks and is no longer a smooth friction surface, these marks indicate uneven wear on the brake shoes, which can cause abnormal noise in scooters.