How to install the fenders on the car

How to install a fender liner: securing and pre-treatment of the car

The original car fenders for a particular car model are molded exactly to the shape of the wheel arch. They can be solid or cut. If a non-original replica is chosen, it is necessary to carefully select plastic elements by shape.

How to Install Fenders on a Car

The majority of Russian automakers continue to put non-standard small size fenders on the car. Plastic covers can not provide full protection to the body – wheel arches begin to rust after a year of operation. Plastic elements will help to fully protect the most vulnerable part of the body. When choosing a product, take into account the material of manufacture and method of fastening. Fenders installation on the car is carried out on the service station, but the protective tuning is easy to make on your own.

What are the underlids on the car for?

When driving, dirt, sand, water, gravel flies from under the wheels of the car. The particles hit the wheel arch, gradually destroying the factory galvanized metal. Water and salt sprinkled on the streets in winter penetrates into the cavities, thus creating conditions for corrosion.

Rear underlips

It takes 12 months for an unprotected wheel arch in Niva, for instance, to start rotting. For foreign cars with a thick layer of factory galvanized (for example, models “Volvo”), the period of destruction of the metal increases up to 18 months. The only way to extend the life of the arch is to use additional protection in the form of anti-corrosion treatment and protective lining.

Proper treatment of car fender before installing fenders and the use of pads from ABC plastic or polyethylene also reduce the noise in the cabin by 50%.


Fasteners for car fenders depend on the material of the lining and its shape. The most common way – mounting on self-tapping screws and clips, a little less common – on pistons and snaps. In most cases, the covers on the car are mounted by the technology provided by the manufacturer.

Self-tapping screws

Self-tapping screws for car fenders in 80% of cases are used to install an entire cloth. For the installation of plastic protection will require 5-7 self-tapping screws for fixing at the edge and 1-3 – for fixing the part in the depth of the arch.

Self-tapping screws

Choose galvanized self-tapping screws standard length of 16 mm with a flat head. Screw them into the metal of the arch, securely fixing the underliner. Many drivers rightly believe that the installation on the self-tapping screws leads to rapid corrosion in places screwed. The screw destroys the anticorrosion of the arch – moisture quickly penetrates into the hole.

To prevent this from happening, during installation, the arch is treated with liquid anti-corrosion, such as “Moville”, ML, etc., each screw is dipped in puszalo or “Moville”.

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It is possible to fix fenders on a car with the help of pistons. This way install protection on many models of SUVs Suzuki, “Toyota”, “Honda”. The piston is made of high-strength ABS plastic and has a length of up to 20 mm. A characteristic feature is the presence of a double fastener skirt, which tightly presses the panel to the wheel arch.


Each manufacturer develops its own types of pistons for car underlays (fasteners are usually suitable for a particular model). The cost of 1 piece can go up to 100 rubles. For example, for the models of Mitsubishi and “Toyota” supplied pistons number 000139882, made of black heat-resistant polymer, length 18 mm. The product has a small skirt and a conical shape of the rod, installed in the original holes in the arch.


Snaps, or S-shaped brackets, are used when installing one-piece fenders made of ABS plastic and fiberglass. Such material is highly rigid, its structure does not allow the panel to be fixed tightly around the entire perimeter. During movement, the part should have minimal space for vibration, otherwise a break will follow.


For this type of fenders use latches made of high-strength plastic. You do not need to drill the body – the regular holes are enough to install 2-3 screws, which securely fasten the panels on the edges and top.

Such non-rigid coupling of the underliner with the body ensures reliable protection of the arch from the penetration of moisture and salt reagents.


Clips are a type of piston fasteners for car undercovers. The elements are made of plastic, have a universal size – clips can be used as a substitute for the original piston.


The disadvantage of the clip is considered a short length of the tip. When using a non-original fixing element, drivers screw 2-3 self-tapping screws along the outer edge of the panel for reliable installation.

Pre-treatment of the car wing before installation

Polyethylene underwings are highly durable, resistant to temperature fluctuations. But the quality of installation will be leveled, the body will quickly begin to be covered with corrosion plaques, if the wheel arch is not pre-treated. Procedure:

  1. Wash and dry the inside of the fender thoroughly.
  2. Clean any possible rust spots, treat with an inhibitor.
  3. Carry out surface anti-corrosion treatment with wax-based anticorrosives, liquid compositions with a large quantity of zinc.

It may be necessary to apply anticorrosion or antigravior again (depending on the condition of the metal).

Fender covers are installed in the regular places of the body. If self-tapping screws are used, they are treated with brushwood. If you have to drill new holes in the body, you must also treat the bare metal with couplant.

Installation Instructions

Original car fenders for a particular car model are molded exactly to the shape of the wheel arch. They can be solid or cut. If a non-original replica is chosen, the plastic elements must be carefully matched in shape. Polyethylene undercovers are easily heated with a construction hair dryer and “adjusted” to the wheel arch. Fiberglass panels have high rigidity – when fitting can break.

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Fenders replacement with your own hands

Replacement of fenders with their own hands

If you choose an analogue, it is recommended to take cut underwings: they are easier to install in those models where the wheel arch is divided by the protruding shock absorber strut.

It is possible to place the fenders on the car correctly yourself:

  1. Poddomkrat auto or install on the elevator. This will facilitate the process of anti-corrosion treatment of the arch and installation.
  2. Remove the wheels.
  3. Clean the arch, carry out anti-corrosion treatment.
  4. Measure each underliner, if necessary, warm the plastic with a hair dryer for greater accuracy of fit. The tighter against the body the better. The likelihood of the tire clinging to the wing liner with the wheels turned and the maximum suspension travel is minimal.
  5. Start mounting from the top center section, going down to the bottom of the body.

The manufacturer gives a warranty of up to 8 years for their underwings. Drivers and locksmiths think this is just a figure: it is impossible to determine how long the part will last. It all depends on driving conditions, time of year, etc. 8 years is the maximum shelf life of a polyethylene and plastic element in storage. This is the only way this figure can be considered.

Installation of underlip on the car with their own hands

Wheel arches – the most exposed to mechanical impact part of the car. Nevertheless, some motorists are confident that the factory protection is able to cope with its duties. Others are absolutely convinced of the need to take additional measures to protect the metal of wheel arches, otherwise in a few years driving on domestic roads, they will get damages, “incompatible with life”.

Fenders rear Jimny

Let’s see which of them is right.

Protecting wheel arches: why do we need it?

Stones and other objects flying out from under wheels, moved by centrifugal force, rush upwards, where they meet the inner surface of wheel arch. As you know, water grinds stone. In this sense, metal is more malleable to stone. But this is not the only matter. Modern anti-corrosion treatment copes quite well with such mechanical influences, while protecting the metal from corrosion.

But if chemical factors come into action (we remember about winter reagents for ice), such protection appears to be powerless. That’s why we need undercovers.

Many automakers install their own protection on wheel arches. Usually it is a thin plastic, which under the influence of gravel, sand, silt, salt and other factors eventually breaks down. So the question of why you need to install undercollars on your car is still quite relevant, especially for older cars. Car owners should just carefully monitor the condition of the inner cavity of wheel arches (as well as the bottom), and if it inspires concern, take steps to avoid further destruction.

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Fender repair

There is no better way to do this than installing additional protection. So let’s consider what are underlips, what they are and how they can be installed by yourself without resorting to the help of car-care centers.

Varieties of fenders

There are several ways to protect car arches. Consider the most popular and common of them:

  • plastic underfenders. The soft plastic locks replaced the metal fenders, which were very common in Soviet times. They had a good service life, but were heavy and inconvenient to install. Plastic products are devoid of these disadvantages, almost as good as they are in terms of mechanical strength. They are much more flexible, lighter, characterized by high wear resistance, easy to install. In the retail store there are products of all shapes, designed for almost all domestic models and most foreign cars. And the cost of plastic is not an example below the metal. Their main drawback – the need to attach to the metal with screws – even if this place is treated with anti-corrosion composition, over time is where you can form a focus of rust;
  • the fiberglass underlidkolki by its characteristics little differ from the plastic – low weight, durability and immunity to temperature and atmospheric factors makes them a good, though more expensive alternative to plastic;
  • Liquid lockers have long become the de-facto standard for the application of anti-corrosion / anti-gravel layer in the factory. It is possible to form such an additional layer yourself by using a suitable liquid, which is abundantly available in the trade network. The main advantage of liquid lockers is the ease of treatment of all previously cleaned surfaces, regardless of their geometry. The disadvantage is also quite obvious – short-lived coating (average life – 2-3 years);
  • armor film – a type of metal protection, which has appeared relatively recently. However, in the factory conditions the technology has already proved itself positively, it is used to protect all exposed body parts: bumpers, sills, lights of optical devices. The strength of these films is not worse than plastic, plus they are transparent, that is, do not spoil the appearance of the car. The only significant drawback is the complicated technology of application;
  • Fenders from ABS plastic have approximately the same set of pluses and minuses, as the usual polyethylene – at a small weight and cost they are not very durable, in addition they have low weather resistance. It is not recommended to press them to the arches too tightly because of the risk of cracking, and the lifetime of such products is low;
  • Aluminum lockers, as well as galvanized ones, are practically not used nowadays. Despite their high mechanical strength, they have some drawbacks (you need to use rubber seals, risk of cracking or deformation in the place of fastening).
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Fenders installation on the car


Only liquid lockers do not require the use of fasteners. All their other varieties need to be somehow fixed, fastened. Different manufacturers handle it in different ways. Thus, domestic plants prefer to use self-tapping screws, car manufacturers from Asia use both self-tapping screws and clips. In the U.S., mostly plastic clips are used, and in the Old World use many varieties of fasteners.

Let’s consider all the common ways to attach underfenders:

  • Clips are used to attach not only the fenders, but also other parts of the body and interior (for example, trim). An alternative name for this type of fastener is a spring clip. There is a reason for this name: the fixation occurs due to the expansion of the cut part of the clip after its installation;
  • pawls, like clips, do not provide perfect mounting rigidity, but their main advantage is non-traumatic way of installation, used mainly for rigid types of underpads (fiberglass, ABS-plastic);
  • self-tapping screws are the easiest to use, have a longer service life, but leave behind holes in the body part. It is recommended to use only galvanized products, and the place of fastening to be treated with anti-corrosion composition;
  • Pistons can also be called a common and versatile way to fix automotive parts. The fixing capability remains high even if the piston does not go all the way into the hole;
  • bolt + nut – a type of threaded fastening, characterized by high reliability of connection and its low aesthetic value. Requires anti-corrosion treatment.

Fenders installation

Noise isolation

Wheel arches along with the engine compartment are one of the most accessible places in terms of penetration of external noise into the cabin. The under-hood sound insulation is usually done on a good level, so the sounds of the engine don’t really get inside the car. Another thing is about the arches, which perfectly transmit the acoustics of the tires’ work. So, together with installation of anticorrosive and antigravian protection, it is necessary to think about additional sound insulation. Here is also a considerable choice of means and ways, from liquid materials to special gaskets. You can also buy fenders with already applied noise-absorbing coating.

What will be required for installation of the fenders

Everything depends on the type of lockers used. So you need to start with their selection. In the retail network, they are represented by sets, but you can buy underpads separately, if there is a need. Original products are expensive, but put them in a landing place is easy, there are no problems with compatibility in this case, unlike analogues.

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What will be required, in addition to the lockers:

  • material for noise insulation. The most common – vibroplast, which, in addition to noise insulation properties, will protect the body from the effects of moisture;
  • material for anti-corrosion treatment of those places where fasteners or places of contact of the locker with the body are used;
  • construction hair dryer – used to cover the arch with vibroplast, to preheat some varieties of lockers, especially non-original;
  • fixing the underlid (self-tapping screws, clips, snaps). With the help of clips you can attach lockers to plastic bumpers, self-tapping screws are used for fixing to metal body parts.

Algorithm of installing lockers with your own hands

Mounting lockers on the front arches in most cases is a simpler operation. The reason is simple – here there are more opportunities to install underpads without self-tapping. How to do this, we will try to describe. The task is simplified by the possibility of fixing to the side edge of the plastic bumper, which on most modern models adjoins the wheel opening. It is clear that the risk of corrosion in this place is reduced to zero. In addition, lockers can be installed in existing grooves, in which case additional fixation is often not needed at all. Another simple option – fixing the underlips to the mudguards, in this case the self-tapping screws can be used in the area of the arch post, where the metal of the body is well protected.

Installation of rear lockers is more complicated:

  • You need to start with fitting the fenders and trimming the protruding parts;
  • then prepare the surface of the metal (free it from dirt and rust) and immediately treat it with mastic or other similar substance;
  • Now mono proceed to the installation of the locker. If you can not do without self-tapping screws, try to minimize their quantity not to the detriment of the strength of the connection;
  • Try to use plastic fasteners (clips, pistons, snaps) where possible;
  • If there are doubts in a reliable fixation, it is possible to glue places of fastening accurately.

Over time, lockers that are not initially in clearance with the body may come loose, so you must keep an eye on them during the operation of the machine. If such places are found, it is necessary to urgently take measures aimed at eliminating the deficiencies. Otherwise, the gaps will inevitably become a place of accumulation of dirt and moisture, i.e. a hotbed of corrosion.

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