When the driver is looking for what they are called plastic car door trims, he usually tries to solve a specific problem: protect the body from chips, hide scratches or fix a squeak in the interior. These elements have different technical names depending on their installation location and functionality, and confusion over the terms often leads to the purchase of the wrong parts. In automotive nomenclature, the most common concepts are “moldings,” “deflectors,” or simply “sill plates,” but each of these products plays its own unique role in the overall architecture of the body.
Incorrect selection of components can lead to a loose fit, accumulation of moisture under the plastic and accelerated corrosion of the metal. Knowing the exact terminology allows you to quickly find original catalog numbers or high-quality analogues at disassembly sites. In this article we will analyze in detail the classification of external and internal door security elements, their design features and installation nuances.
Basic classification of external protection elements
The main element that most car enthusiasts are looking for under the query “door trim” is molding. This is a long plastic or rubber strip that runs along the side of the body, usually at the level of the door handles or in the middle of the door leaf. The main task of the molding is to absorb impacts from the doors of neighboring cars swinging open in the parking lot and protect the paintwork from contact with supermarket carts.
The second important element is window deflectors, which are popularly often called “windbreakers”. They are installed in the upper part of the doorway and have a complex aerodynamic shape. Their purpose is to divert the flow of oncoming air and raindrops from the open window, allowing the interior to be ventilated even in heavy rain. They are made of polycarbonate or acrylic plastic, often tinted.
- 🚗 Door moldings - protect the sidewall from impacts and scratches.
- 🌧️ Deflectors (wind deflectors) - provide ventilation without precipitation.
- 🛡️ Door sill covers prevent paint from chipping when getting into a car.
- ✨ Decorative strips - hide joints and improve appearance.
Separately worth mentioning door sills, which are formally located at the bottom of the door, but are functionally connected to the door group. They are internal (metal or plastic plates on the floor) and external (plastic “skirts” covering the bottom of the door and the threshold from the outside). External linings are especially relevant for crossovers and SUVs, where the lower part of the body is most susceptible to the abrasive effects of sand and gravel.
Moldings: design and purpose
Moldings are the most common type of lining found on most modern cars. Structurally, they are divided into hard plastic, soft rubber and combined. Hard versions often have a carbon or chrome texture, serving a decorative function, while soft rubber profiles are intended solely for shock absorption.
Moldings can be fastened using double-sided tape, special clips, or a combined method. In expensive models Mercedes or BMW moldings can be integrated into the overall line of the body, becoming almost invisible. Cheap, universal alternatives often have a simple rectangular shape and are attached only with an adhesive backing, which can lead to peeling of the edges over time.
⚠️ Attention: When installing moldings with double-sided tape, it is critical to degrease the body surface with alcohol or anti-silicone. Applying the sticker to a dusty or greasy surface will cause moisture to accumulate under the plastic, causing corrosion of the metal.
Modern design trends dictate the abandonment of massive overlays in favor of hidden protection elements. However, for vehicles operated in dense city traffic, the presence of a protruding shock-absorbing profile remains the most effective way to preserve the resale value of a body. Some manufacturers use polyurethane foam, which regains its shape after impact.
Window deflectors: types and installation methods
If moldings protect against mechanical damage, then deflectors solve comfort problems. They create a zone of calm air near the window, changing the aerodynamics of the flow. There are two main types of fastenings: push-in (inserted into the rubber seal of the window opening) and glued (fixed on the outside of the door).
Plug-in models are considered more aesthetically pleasing, since they do not have visible fasteners from the outside, but their installation requires care so as not to damage the window lift mechanism. Glued-on options are easier to install, but require a perfectly flat surface and high-quality preparation. The material used is usually smoky polycarbonate, which is UV resistant and does not turn yellow over time.
| Mounting type | Difficulty of installation | Impact on review | Risk of damage |
|---|---|---|---|
| Plug-in | Average | Minimum | Middle (seal) |
| On tape | Low | Depends on the shape | Low |
| Combined | High | Minimum | High |
Quality deflectors such as brands Heko or Cobra, have a rough surface that prevents raindrops from sticking and reduces aerodynamic noise. Cheap Chinese analogues can create a whistle at high speeds due to a violation of the air flow geometry. When choosing, it is important to pay attention to the thickness of the plastic: material that is too thin will vibrate while moving.
The secret to installing deflectors quietly
Before gluing the deflector, warm the lining itself and the car body with a hairdryer to a temperature of 20-25 degrees. This will activate the adhesive base and ensure maximum adhesion even in the cold season.
Protection of thresholds and lower parts of doors
The bottom of doors and threshold areas are a blind spot for many owners until corrosion sets in. Plastic door sills (often called “skirts” or “plugs”) cover process holes and metal from water, salt and reagents. On many modern cars, especially French and Korean brands, these elements are made of soft plastic and are easily pierced by stones.
Internal door sill covers perform a double function: they protect the end of the threshold from shoes when boarding and serve as a decorative element of the interior. They can be made of stainless steel, backlit aluminum or durable textured plastic. Installation of such overlays on Kia Rio or Hyundai Solaris has become an almost mandatory procedure after purchase due to the low abrasion resistance of the standard coating.
- 🦶 Protect the end of the threshold from heels and soles.
- 💧 Prevent moisture from entering hidden body cavities.
- 🎨 Hides factory welding or painting defects.
- 🔊 Reduce noise levels from wheel arches.
For SUVs, reinforced linings made of corrugated plastic or metal are relevant, which absorb impacts when overcoming fords or coming into contact with stumps. It is important to (check) the condition of the fastenings of such linings: if dirt gets under them, the process of rotting of the metal under the plastic will accelerate due to the “compress” effect.
⚠️ Attention: If you notice that paint has begun to swell under the plastic sill trim or a red coating has appeared, immediately remove the element. Ignoring the problem will lead to through corrosion and costly body repairs.
Internal plastic elements of doors
Speaking of linings, we must not forget about the interior. The inside of the door is closed door card (door card), which consists of a hard base and soft linings. Drivers often look for plastic covers for handles, speakers or power window buttons, which over time are wiped off or scratched by keys.
Decorative inserts imitating wood, aluminum or carbon fiber are glued on top of standard plastic. They allow you to change the interior style without replacing entire door panels. However, when purchasing such kits for models Volkswagen or Toyota you need to be careful: low-quality plastic may have differences in shade or geometry, which will be noticeable.
☑️ Check before purchasing pads
Internal elements also include protective films and linings on the ends of the doors. They protect the edge of the metal from chipping when slamming and prevent water from entering the interior through the seal. Installing such little things takes minutes, but significantly extends the life of doorways.
Materials of manufacture and their durability
The durability of the linings directly depends on the material. ABS plastic (ABS) is the most common option and is flexible and impact resistant, but can fade in the sun. Polypropylene (PP) is more resistant to chemicals and temperature changes, often used for thresholds. Rubber (EPDM) is ideal for moldings due to its elasticity, but can become shiny over time.
The premium segment uses coated materials Soft Touch or genuine leather, but such linings require regular care with special conditioners. Cheap plastic becomes brittle in the cold and can burst if washed carelessly with a Karcher. Therefore, when choosing between the original and a cheap analogue, it is often better to overpay for the quality of the polymer.
There are also composite materials with the addition of fiberglass, which combine the strength of metal and the lightness of plastic. They are rarely found in the mass market, but are popular in tuning sports cars. For everyday use, high-quality paint-painted plastic remains the best choice.
Tip: To extend the life of black plastic covers, use protective compounds with UV filters. They prevent color fading and the appearance of a whitish coating.
Nuances of installation and care of linings
Installation of most plastic elements does not require professional equipment, but does require cleanliness and accuracy. A critical step is surface preparation: washing, drying and degreasing. Skipping any of the steps guarantees that the lining will fall off in a month or corrosion will begin underneath it.
When mounting with clips, be careful not to damage the plastic caps, as they often break when reused. It is recommended to have a spare set of fasteners. If the overlay is attached with 3M tape, after gluing it is advisable to press it with a weight or use masking tape to fix it for 24 hours until the glue is completely polymerized.
- 🧼 Regularly wash the space under the linings when washing the body.
- 🚿 Do not direct a powerful stream of water at right angles into the joints.
- 🧴 Use plastic ink to restore color.
- ❄️ In winter, do not tear off the frozen ice by force so as not to break the plastic.
Caring for deflectors involves using a soft sponge, as abrasive sponges quickly leave matte scratches on a glossy surface. For moldings with chrome, there are special polishes that remove oxides. Regular inspection of the condition of fasteners will help avoid loss of parts on the go.
How to remove the old trim without damaging the paint?
For safe removal, use a hair dryer and fishing line. Warm up the gluing area to soften the tape, then carefully “saw” the layer of glue between the body and the trim with fishing line. Remove glue residues with a special remover or oil, avoiding aggressive solvents.
Can plastic trims be painted?
Yes, most ABS plastic covers can be painted. This requires a special primer for plastic (adhesion promoter), base paint and varnish. Without primer, the paint will peel off in pieces in a short time.
Why does the plastic cover squeak?
Creaking occurs due to friction between plastic and metal or loose fasteners. You can fix the problem by lubricating the contact points with silicone grease or placing pieces of anti-creaking material (porous material).