Increased noise level in the car interior when driving is one of the main reasons for rapid fatigue of the driver and passengers. The main sources of unpleasant sounds are often wheel arches, where the impacts of stones and the hum of rubber resonate across the metal body.
An effective solution to this problem lies in the complex treatment of the inside of the arches and the outside of the plastic fender liners. Sound insulation of fender liners allows not only to reduce the overall acoustic background, but also to protect the metal from corrosion caused by moisture and reagents.
In this article we will analyze in detail the surface preparation process, the selection of optimal materials and the technology of their application. You'll learn how to turn a loud car into comfortable transportation in just a few hours of work in a garage environment.
Selection of materials for processing wheel arches
The first stage of any quality work is the correct selection of components. The market offers many solutions, but not all of them are suitable for the wheel arch area. This requires a combination of vibration absorption, sound insulation and moisture resistance.
The basis is vibration isolator on a bitumen or mastic basis. It is this that dampens vibrations of metal and plastic, preventing the transfer of vibration to the body. For the outer side of the fender liner, it is better to choose materials with a foil layer or a special protective film.
The second important component is the sound absorber. Closed cell foams that do not absorb moisture are often used. The use of open porous materials, such as regular felt, is strictly prohibited in this area.
- 🧱 Vibration-absorbing mastics on a bitumen basis with aluminum foil.
- 🛡️ Liquid noise insulation (liquid fender liner) to seal joints and protect against chips.
- 💧 Degreaser and anti-corrosion compounds for metal preparation.
- 🔨 Primer to improve the adhesion of the adhesive layer to plastic.
When choosing the thickness of the material, it is worth considering the gaps between the fender liner and the body. If the layer is too thick, the plastic will begin to rub against the wheel or suspension components, causing a squeaking noise.
Wheel removal and surface preparation
The quality of sound insulation fit directly depends on the cleanliness of the surface being treated. Ignoring the preparation stage will result in the material coming off after the first wash or falling into a puddle.
You should start work by removing the wheel. This will provide free access to all areas of the arch and will allow you to visually assess the condition of the metal under the plastic. If the fender liner is attached with clips and screws, it must be removed completely.
⚠️ Attention: Before starting work, be sure to place the vehicle on a flat surface and secure it with wheel chocks. Working with the raised side of the machine requires compliance with safety regulations.
The surface of the plastic fender liner and the inside of the arch must be thoroughly washed to remove dirt, sand and oil stains. After drying, degreasing should be carried out using White spirit or specialized anti-silicone.
If pockets of corrosion are found on the metal of the arch, they must be cleaned to bare metal and treated with a rust converter. Only after this can you apply the primer and begin gluing.
To improve the adhesion of the adhesive layer to smooth plastic, it is recommended to apply a thin layer of plastic primer. This is especially true for older cars, where the plastics have become smoother and slipperier.
☑️ Preparation for sound insulation
Vibration insulation technology
The process of gluing vibration insulation requires care and adherence to temperature conditions. The optimal room temperature should be at least +15...+20°C, since cold material loses its elasticity and does not adhere well.
Vibration insulation sheets are cut into convenient pieces. Don't try to cover 100% of the surface in one piece - this will create air pockets. It is better to use the “scales” method or cover 70-80% of the area of the most vibration-loaded areas.
After applying the material to the surface, it must be carefully rolled with a hard roller. Movements should be from the center to the edges to expel all the air from under the layer. The quality of the rolling is checked visually: there should be no whitish spots left.
Pay special attention to the edges of the sheets. They need to be pressed firmly with your fingers or the end of a roller to ensure a tight seal. If the vibration insulation has a foil layer, make sure that it is not damaged during installation.
Do I need to heat the material with a hairdryer?
In most cases, modern bitumen materials become plastic from the heat of the hands. However, if the garage is cold or a thick layer is used (more than 3 mm), preheating with a hair dryer to 40-50 degrees will make installation easier and improve adhesion. The main thing is not to overheat the material to the point of fluidity.
Processing joints and applying sound absorber
After the vibration layer has dried and hardened, you can proceed to applying the second layer. This is where sound-absorbing materials come into play, working on the principle of dispersing sound waves.
For the inside of the arch it is often used liquid sound insulation or mastic. They are applied with a brush or spray, creating a monolithic layer without seams. This perfectly seals the joints between the body and the fender liner.
If you use sheet materials, they are glued on top of vibration insulation. It is important to use materials with a closed cell structure that are resistant to water. Open pores will quickly absorb moisture and stop working, and can also become a source of odor.
It is better to additionally coat the joints between the sheets and the places where the clips are attached with sealant or mastic. This will prevent water from getting between the layers of the sound insulation “pie” and the formation of condensation.
Don't forget about the technological holes. They cannot be sealed tightly if water drainage is provided there. Use special valves or leave access for moisture at the lowest point of the arch.
Comparison of material characteristics for arches
To make it easier for you to navigate the variety of products, we have prepared a comparative table of the main types of materials. She will help you choose the optimal solution for your budget and tasks.
| Material type | Efficiency | Difficulty of installation | Moisture resistance | Weight (per arch) |
|---|---|---|---|---|
| Bitumen vibration insulation | High | Average | High | ~1.5 kg |
| Liquid fender liner | Average | Low | Very high | ~0.8 kg |
| Foamed polyethylene | Average | Low | High | ~0.3 kg |
| Felt (not recommended) | High (dry) | Average | Low | ~0.5 kg |
As can be seen from the table, bituminous materials provide the best comprehensive effect, but add weight. Liquid formulations are easier to apply, but require time to dry. Combining methods often gives the best results.
When calculating the amount of material, keep in mind that on average one wheel arch requires 2 to 3 square meters of vibration isolation, depending on the size of the car and the area to be treated.
Assembly and quality control of work
The final stage is installing the fender liners in place. Before doing this, make sure that all layers of materials are dry and securely fixed. Check that the edges of the materials do not protrude into the wheel rotation area.
When installing a plastic locker, make sure that the clips are intact. It is better to replace old, cracked fasteners with new ones so that the fender liner does not dangle and create vibration, negating all the work.
⚠️ Attention: After installing the wheels, make a few turns by hand to make sure there is no contact between the tire and the sound insulation elements. Extraneous rustling noise when the wheel rotates is unacceptable.
The first trips after modernization may be accompanied by a specific smell of materials. This is normal for new bitumen compositions and goes away after 2-3 days of operation with open ventilation.
High-quality sound insulation of arches reduces the overall noise in the cabin by 3-5 dB, which subjectively feels like a halving of the volume.
Frequently asked questions (FAQ)
Is it possible to glue sound insulation directly onto dirt or rust?
Absolutely not. Adhesion of the adhesive layer only works on a clean, grease-free surface. Pasting on rust will preserve moisture under the material, and the metal will rot even faster. The material simply will not stick to dirt.
Do I need to remove the fender liner completely or can I glue it on the outside?
For maximum effect, it is better to remove the fender liner. This will allow you to process the inside of the body arch, which also resonates strongly. Gluing only to the outside of the locker is less effective, since sound passes through the gaps.
How long does liquid sound insulation take to dry?
The polymerization time depends on the air temperature and layer thickness. Typically, initial drying takes 2-4 hours, but the material gains full strength and chemical resistance after 24 hours. In the cold season, the period increases.
Will fuel consumption increase after soundproofing?
Yes, but the change will be minimal and unnoticeable in everyday use. The weight of the materials on the four arches is about 10-15 kg, which is comparable to the weight of one passenger or a full tank of fuel. The effect on dynamics and consumption is negligible.
Can I wash my car with a high pressure washer after treatment?
Yes, if the materials were applied correctly and the edges were carefully rolled. Modern automotive chemicals and jets of water under pressure are not afraid of high-quality vibration and noise insulation. However, in the first days after installation it is better to avoid aggressive washing.