What causes the humming noise at 70 km/h that disappears after 80 km/h?
2 Answers
Get the rear wheel bearings checked at a 4S shop, as they might be abnormally worn. Here are some relevant tips for driving on uneven roads: 1. Driver's posture: When driving on bumpy roads, maintain the correct driving posture by keeping your upper body close to the seat back and holding the steering wheel with both hands to minimize body movement or bouncing. If your body loses stability due to the vehicle's bouncing, it will affect smooth acceleration and lead to a loss of control over the vehicle. 2. Driving method: For short and slightly uneven roads, you can coast through in neutral. On continuous small bumpy surfaces, maintain an appropriate constant speed and try to choose relatively flat ground to pass through slowly.
Hi, as an enthusiast who often tinkers with cars, I frequently encounter similar issues. The buzzing sound usually occurs at specific speeds because the resonance frequency at 70 km/h triggers a problem with a certain component. Once the speed exceeds 80 km/h, the RPM changes, the frequency no longer matches, and the sound disappears. The most common causes are unbalanced tires, where tire wobbling at the resonance point generates noise, or worn wheel bearings that produce unusual sounds at specific speeds. Last year, my car had the same issue—the buzzing was incredibly annoying. Later, I took it to the shop for a four-wheel dynamic balance and discovered the problem was a loose bearing. After replacing it, the noise was gone. If you want to inspect it yourself, first check if the tire wear is even and feel the bearing area for any overheating. Delaying repairs could lead to more severe damage, such as unexpected tire detachment or bearing fracture, increasing the risk of high-speed accidents. So, scheduling a professional inspection as soon as possible is the most worry-free approach. For regular maintenance, pay attention to periodic checks of these vulnerable parts.
