In-depth transformation of BMW 730 Li’s entire car quietness: practical experience of the top Japanese flute god’s sound insulation technology

For car owners with luxury cars, the pursuit of comfort and quietness is endless. In the eyes of others, the luxury car itself has achieved a perfect driving experience, but in the eyes of those who really know and love cars, there is still room for excellence-just as its original audio system is already superior, there are still a large number of car owners choose to upgrade later in order to pursue a more extreme auditory feast. For this reason, with our exquisite craftsmanship and profound experience, we have successfully implemented in-depth sound insulation and noise reduction projects for many top models such as Porsche Cayenne, Mercedes-Benz S-Class, Land Rover Range Rover and Velar, and won the trust of high-end car owners.

Today, we once again welcome a BMW 7 Series owner who has strict requirements for quietness to carry out sound insulation and noise reduction construction for his car. Below, we will share this professional upgrade process with riders and netizens through a detailed atlas of construction details.

The sound insulation project of the whole car involves the disassembly of a large number of interior parts. The core issue that car owners are most concerned about is whether there will be troublesome abnormal noises after the construction is completed. We must point out that the root cause of abnormal noise often lies in irregular disassembly and assembly operations, inadequate assembly or damage to precision parts such as buckles. Therefore, it is crucial to choose a professional construction team with rich experience and excellent skills, especially good at handling high-end models. For a flagship model like the BMW 7 Series, its complex internal structure requires the builder to have extremely rich practical experience and rigorous and meticulous technical skills. When choosing a modification service, we strongly recommend that you take the professional qualifications of your team and the quality of your case as your primary consideration, rather than just comparing prices.

The picture shows the state of BMW 730 Li interior parts after they have been disassembled professionally and orderly, making perfect preparations for the subsequent accurate paving of sound insulation materials.

The effect of sound insulation and vibration stopping construction in the chassis area is completed. We use high-density vibration-stopping plates for large-area full-paving mounting. This process is not random, but a targeted solution adopted after scientific analysis based on the unique sheet metal structure and material characteristics of BMW models, aiming to maximize the suppression of low-frequency resonance and achieve the best vibration and noise reduction effect.

On top of the anti-vibration layer, we carefully laid top-level environmentally friendly sound-absorbing cotton. Our store always insists on using white sound-absorbing cotton that reaches medical grade. In order to ensure the absolute healthy and odor-free environment in the car, we resolutely abandon the cheap recycled materials commonly available on the market and choose products with the highest environmental protection standards regardless of cost.

The sheet metal structure behind the rear seat rests is also an important noise transmission path. As shown in the figure, we have also thoroughly stopped the vibration of this hidden area to prevent any “fish that may resonate”.

After the vibration stopping is completed, it is also covered with thick medical-grade sound-absorbing cotton to form a double barrier of “vibration stopping + sound absorption” to ensure the comprehensiveness and durability of the sound insulation effect.

The trunk is the main gathering area for road noise and exhaust pipe resonance. We have carried out dense anti-vibration mounting on the bottom plate and the inner hub raised parts to fundamentally strengthen the rigidity of this area and suppress vibration.

The construction details of the hub positions on both sides are displayed. Every curved surface and corner have been carefully cut and pasted to ensure that the material and sheet metal are closely fitted to maximize efficiency.

Finally, two layers of high-density sound-absorbing cotton are laid in the trunk area to completely absorb the residual noise and create an extremely quiet luggage space.

Doors are the main gateways for wind noise and external noise intrusion, and their sound insulation works are crucial. For high-end models such as BMW 7 Series, the internal structure of the door is complex, involving precision parts such as glass lifts, and unexperienced technicians are not competent for its non-destructive disassembly and assembly. The picture shows the state of the four-door interior trim panel after it is removed.

Interior structure of front door

Rear door interior structure

The inner sheet metal vibration stopping effect of the door is completed. We adopt a scientific method of combining strip stickers with block stickers to suppress vibration while avoiding excessive weight of the door, which will affect the life of the elevator and the feel of opening and closing the door.

The outer layer of the door is sealed. Installing sound insulation materials on the inside of the door interior panel to form a closed box structure can not only enhance the thickness of the door, but also significantly improve the sound environment of the audio speaker.

Hood sound and heat insulation construction. The first layer uses a vibration stop plate to strengthen the rigidity of the cover plate and reduce the resonance caused by engine vibration; The second layer is specially pasted with high-performance heat insulation, fire-retardant and flame-retardant cotton, which effectively reflects engine heat, protects the hood paint surface, and further absorbs cabin noise.

The silver layer in the picture is the special aluminum film insulation cotton installed, which has excellent fire retardant, flame retardant and heat insulation reflection properties.

The four-wheel fender and lining are the most direct path for tire noise to enter the cabin. We removed the lining shield and carefully pasted memory foam sound-absorbing material with slow rebound characteristics on the inside to efficiently absorb the rolling noise and gravel impact sound caused by the friction between the tire and the ground.

After all construction steps are completed, the critical in-situ refined restoration installation is carried out. Subsequently, we launched a rigorous road test inspection process: we experienced the leap-forward improvement of sound insulation and noise reduction effects on the spot under various road conditions, and checked all electrical functions, door and window lifting, interior assembly gaps, etc. of the vehicle one by one to ensure that the vehicle performance and condition were 100% restored to the best, even exceeding the quiet level of the original factory.