Car body protection and maintenance – step by step

The underbody is a part of the vehicle that is particularly exposed to elements such as rain, snow, mud, sand, salt or stone impacts. These elements can accelerate the corrosion process, leading to damage. A systematic check of the condition of the chassis is therefore important to keep the car in the best possible condition and prolong its life. In this article, we will discuss some of the basic steps that need to be taken to protect the undercarriage from corrosion and outline the benefits of regular maintenance.

Why perform underbody maintenance?

Underbody corrosion is one of the biggest threats to the efficiency of our car. Corrosion is a chemical process in which metals – such as steel – rust and lose their strength as a result of exposure to moisture, salt, mud and other substances normally found on roads. Progressive corrosion of the chassis can lead to a number of serious problems, including damage to the plating, frame or other structural and load-bearing elements, which can compromise the safety of the driver and passengers. In addition, this damage is often difficult to repair and requires specialised bodywork and mechanical repairs, which incur significant costs. To minimise the risk of chassis corrosion, regular cleaning and maintenance is important. When it comes to maintenance, one could say 'prevention is better than repair'.

How to protect the uderbody of a car?

Step 1: Cleansing

Chassis maintenance should start by removing plastic parts such as wheel arches, sill trims, engine covers, muffler, etc. We then proceed to thoroughly wash the undercarriage and clean it of any dirt. This is best done with a high-pressure cleaner. If you do not have one, it is advisable to have this service carried out at a car wash, which will definitely improve the quality and speed of the work. We then need to dry the chassis, or simply wait for it to dry on its own. After washing, we inspect the undercarriage and assess the condition of all components. Loose rust should be removed mechanically with a wire brush or, if access is available, with BOLL abrasive disc mounted on a drill. Our disc is made of a hard non-woven material with very good abrasive properties. Thanks to its open structure, it does not clog or damage the metal. The sanded and cleaned areas should be 'blown' with compressed air and then degreased. Only on such a prepared surface can further products be applied.

Step 2: Body protection and wrapping

Before we start the maintenance process, we need to mask the car body with foil and tape. We dismantle the wheels and protect components such as the engine, brake system, electrical system, exhaust system and any rubber components. We leave only those elements that will be covered with coating.

Step 3: Rust neutralisation

Once the rust foci have been sanded away, we need to protect the sheet metal from further corrosion development. For this purpose, we use a rust convertor. It is a product based on high-quality epoxy resins with excellent priming and anti-corrosive properties. It forms a very hard coating, protecting the substrate from the elements and can be applied directly to rust. Rust neutraliser is available as a spray and also as a liquid for application by brush, roller or spray gun.

Step 4: Epoxy primer

The chassis thus prepared is coated with 1:1 epoxy primer. This creates an insulating layer, providing a very high level of protection against rust, and also increases the adhesion of subsequent layers. BOLL epoxy primer has an anti-corrosion rating of C4M. This means that our product provides long-lasting protection against corrosion even in industrial conditions and constant contact with seawater.

Step 5: Application of the preservative preparation

Once the products used so far have dried, we can proceed with maintenance. The underbody preservative comes in three variants: spray, gun and can - brushable. We reach for the spray when we want to top up existing maintenance because we have found minor cavities on visual inspection of the chassis. In cases where the entire underbody is being maintained, a gun or brush product should be used. Whichever one we choose, the principle is the same: we need to thoroughly coat all parts of the chassis, including metal suspension components, stringers and frames on off-road vehicles. Brush maintenance will particularly work well where you want to build up a thick structure, such as in the wheel arches, which is where most dirt accumulates.

One layer or approx. 1.5 mm is sufficient protection, but another will further enhance the protection.

When maintaining the chassis, we should not forget to maintain the internal profiles of the car. Moisture usually accumulates in these areas and corrosion starts to spread. To carry out this operation, the best product is a closed car body profile protector that comes in two variants: as an aerosol and for the gun. The specially designed aerosol nozzle equipped with a tube allows you to reach even the furthest corners of the car. 

Remember that preservative must not be applied to the underside of the engine, the area around the gearbox, exhaust and brake components!

When the work is finished, we must leave the car to dry for about 24 hours at 20°C.

It is worth noting that underbody maintenance, in addition to protecting against corrosion and damage, also has a soundproofing effect, which is excellent for increasing driving comfort.

In addition to the underbody maintenance, we should also protect the car body cavities. Moisture usually accumulates in these places and corrosion begins to spread. The best product to perform such an operation is BOLL inside coating, available in two variants: spray and gun. A specially designed aerosol nozzle with a tube allows you to reach even the furthest corners of the car cavities.

Step 6: Assembly

If it is necessary to wash elements that have inadvertently been contaminated with preservative, we can use Boll silicone remover without fear of damaging plastic or painted elements. If we are cleaning the painted parts of the bodywork, we should use a soft fleece soaked in silicone remover and gently scrub away the dirt.  Once the maintenance has been carried out, we proceed to install all previously dismantled components in the reverse order of removal. 

How often should we carry out maintenance?

Proper maintenance protects the car for 4-5 years.  Remember that the condition of the underbody should be checked regularly to prevent damage. When you notice chips, cracks or signs of rust, you need to take action. It is best to think about maintenance in autumn, before the car goes out on roads covered in snow, sand and corrosive salt. And also in spring, when checking the condition of the underbody reveals post-winter damage and the beginnings of corrosion. Once the winter period is over, we must also remember to thoroughly wash the underbody to remove harmful substances, especially road salt residues. Then the protective layer will last the longest.

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