What Causes the Rear Axle Noise in BMW 5 Series?
1 Answers
BMW 5 Series rear axle noise causes are as follows: Noise due to improper gear backlash: Under normal conditions of main reducer bearing preload, metallic impact sounds occur at the rear axle during initial vehicle movement or gear shifting for a short period. When the vehicle speed stabilizes, the impact sound turns into continuous noise. During sudden throttle changes, irregular "clicking" or "clunking" sounds appear at the rear axle - this generally indicates excessive gear backlash. If there's a siren-like "howling" sound during low-speed driving, accompanied by "clanging" noises during acceleration or deceleration and rear axle overheating, this usually indicates insufficient gear backlash. These abnormal sounds are typically caused by severe gear and spline wear, excessive or insufficient gear backlash, or insufficient lubrication. Noise due to uneven gear backlash: When starting or during rapid speed changes, rhythmic "grinding" sounds occur, accompanied by body rear-end vibrations during turns - these are usually caused by uneven gear backlash. Loose differential housing screws, loose ring gear rivets (or screws in some vehicles), causing gear wobbling and jumping during operation which leads to inconsistent gear backlash, are the direct causes of uneven backlash.
