Body corrosion is the main enemy of any car, and most often it attacks the lower part of the sidewalls. Replacement of thresholds It is one of the most complex bodywork, requiring not only welding skills, but also an understanding of the geometry of the body. Ignoring rotten areas can lead to a violation of the rigidity of the structure and problems during the technical inspection.
In this article, we will discuss the process from dismantling old elements to installing new ones, paying special attention to welding technology and subsequent anti-corrosion treatment. Restoration of thresholds With their own hands, it allows you to significantly save on the services of specialized service stations, but requires careful preparation and high-quality tools. If you are willing to spend time and effort, the result is worth it.
Before you start cutting metal, you need to decide on the type of elements to be replaced, since the design may differ depending on the model. There are removable elements that are fastened by bolts, and welded, which are a continuation of the power frame. In 90% of cases on modern passenger cars is found exactly fermentationrequiring the use of a welding machine.
Diagnosis of condition and choice of materials
The first step should always be a thorough diagnosis, since the external state of the paint does not always reflect the real picture. Rot is often hidden under layers of factory anticory or decorative linings, so you will have to use a hammer and a sharp object for an accurate assessment. Tapping helps to identify bloating and hidden foci of corrosion, which are visually invisible.
When choosing a new set, it is important to pay attention to the thickness of the metal and the quality of stamping. Cheap Chinese counterparts are often made of too thin steel, which burns out quickly, or their geometry does not match the factory size. Original thresholds or high-quality analogues of thick metal will ensure the durability of repair and proper fitting of doors.
⚠️ Warning: Never use water pipes or an inappropriate section profile to replace them. This violates the power structure of the body and can lead to the displacement of the spars on impact.
It is also important to purchase supplies in advance, such as epoxy, anti-corrosion compounds and welding wire. Savings on chemistry at the preparation stage will lead to the fact that in a year or two the rust will come out again, negating all the work. Quality anticorcor It extends the life of metal several times.
Necessary tool and workplace preparation
For high-quality work will require a serious set of tools, without which the replacement of thresholds with their own hands will turn into torture. The main tool is a welding semi-automatic, since gas welding gives too much heating and deformation of the thin metal. Argon is also suitable, but requires a higher qualification welder.
- 🛠️ Corner grinding machine (Bulgar) with a set of cut and sweeping circles.
- 🔥 Welding machine (MIG/MAG semi-automatic) and chameleon mask.
- 🔨 Hammers, chisels, rusty-residue cut-outs.
- 📏 Roulette, marker and chalk for marking cut lines.
- 🧤 Personal protective equipment: stings, glasses, respirator.
In addition to the main tool, you will need rods to fix new elements and level gaps. Body geometry It must be kept within millimeters, otherwise the doors will be closed with difficulty or there will be gaps. The use of rods allows you to fix the part in an ideal position before the welding.
⚠️ Note: Work only in a well-ventilated room or outdoors. Welding gases and dust from paint grinding are extremely harmful to the respiratory system.
Workplace preparation also includes ensuring good lighting and reliable grounding of welding equipment. The negative welding wire should be fastened as close as possible to the welding site.It is preferably directly on the doorstep or the spanger to avoid wandering currents that can damage the vehicle's electronics. Disconnecting the battery is a mandatory safety rule.
Removal of old thresholds and cleaning
The dismantling process begins with removing all the interfering elements: plastic linings, moldings, and sometimes doors to provide better access. If the doors remain, they must be carefully protected from sparks and mechanical damage by sealing with paint tape and covering materials. Removal of doors It often facilitates access to the bottom of the opening and allows you to control the quality of the seam from the inside.
The marking of the cutting line is a critical moment that determines the success of the entire operation. It is necessary to step back from the visible edge of the rot 2-3 centimeters towards the whole metal to make sure that all the rust is cut out. Cut the old threshold is most convenient Bulgarian, making longitudinal and transverse incisions, after which the remains are knocked out with a hammer and chisel.
After removing the main metal array, it is required to clean the remaining parts of the spangeron and floor to shiny metal. Cleanup. It is necessary to see the real state of the metal and provide good adhesion for future welding. All residues of paint, soil and rust must be removed mechanically.
☑️ Preparation for welding
Welding technology and installation of new elements
Installation of new thresholds begins with fitting and fitting, since the geometry of stamped parts does not always perfectly coincide with the body. If necessary, the edges of the new part are bent or stretched with a hammer for accurate hitting the contours. Gaps. between the new part and the body should be minimal, but sufficient for the boil (usually 1-2 mm).
Welding should be performed with short seams (articks) of 2-3 centimeters in staggered order to avoid overheating of the metal. If you cook with a long continuous seam, the thin metal of the sills will lead the "wave", and it will be extremely difficult to correct this. After each series of grips, you need to let the metal cool, tapping the seam with a hammer to relieve tension.
Pay special attention to the places of docking of the threshold with the front and rear racks, as well as with the wheel arch. These zones experience maximum loads, so the provager should be of high quality and deep. Carbon-cooked cooking allows you to get a strong connection, but requires the skill of bath welding, so as not to burn through the metal.
| Parameter | Recommended value | Note |
|---|---|---|
| Welding current | 80-120 AA | Depends on the thickness of the metal. |
| Wire diameter | 0.8. - 1.0 mm | Optimal for bodywork |
| The length of the grip | 20-30 mm | To avoid overheating |
| Gap. | 1-2 mm | For good melting |
⚠️ Warning: Do not boil new thresholds "by weight." Be sure to weld temporary spacers between the sills so that when the seams cool down, the body does not collapse inside.
Anti-corrosion treatment and finishing
After welding and cleaning of the seams comes the most important stage – protection of the metal from corrosion. Fresh metal, especially in the zone of thermal influence, is subject to rusting much faster than factory. The first layer is always applied epoxy, which creates a sealed film, oxygen and moisture access.
To protect the inner cavities of the thresholds, special anticores with high penetrating power, often called "movils" or wax compounds, must be used. Processing is carried out through the technological holes with the help of a long probe-sprayer, providing metal coating on all sides. Movieville It displaces moisture and creates an elastic protective layer.
Finishing includes spatula welds, priming and painting in body color. Quality painting not only gives an aesthetic appearance, but also is an additional barrier to an aggressive external environment. Use of the antigrave The lower part of the sills will protect them from stones and sand from the road.
Typical mistakes and expert advice
One of the most common mistakes is poor-quality cleaning of the edges before welding, which leads to weak, porous seams. RustThe stained metal, which remains under a new threshold, will continue its destructive effect, and after a year the part may fall off. Always clean the metal to a characteristic shine.
Another mistake is ignoring the internal processing. Many people think that it is enough to paint the threshold outside, forgetting that rotting often begins from the inside, where condensate accumulates. Hidden cavities They should be treated with anticores first, even before installation, if possible.
Do not try to save on welding equipment by using a manual arc welding inverter (electrode). Thin metal body (0.6-0.8 mm) in this way to cook is almost impossible without holes and severe deformations. Semi-automatic This is the only true choice for body repair in garage conditions.
Do I need to remove the doors when changing the door?
Remove the doors is not necessary, but it is highly desirable. This opens full access to the top of the opening and allows you to cook the seams in a comfortable position. If the doors remain, they need to be very carefully protected from sparks and accidental impacts by the tool.
Which anticor is better to use inside the thresholds?
Best proven compositions on a wax or bitumen-oil basis with corrosion inhibitors. They do not dry completely, remaining elastic, and have water repellent properties. Examples: Moville, Dinitrol, Tectyl.
Can you boil the sills on top or just join?
Factory technology often involves welding together with a support element or a swamp of internal amplifiers. In garage conditions, welding is permissible on top (tape), if good welding of the seam root and the absence of gaps where moisture can accumulate are provided.
How long does the anticory dry before painting?
Depends on the type of composition. Wax anticores for internal cavities can dry for several days, remaining sticky. If you plan to paint the exterior, make sure that the used soil and anticor are compatible with paintwork and completely dried (usually 24 hours).
What to do if the seat belt fasteners on the doorstep rot?
If the seat belt attachment has rotted, simple repairs may not be enough. It is necessary to cut out the rotten area, weld a new reinforced plate (re-set) and only after that set the threshold. Passenger safety is paramount.