Corrosion is the main enemy of any car, and Nissan Sunny was no exception. Over time, the metal in the lower part of the body, especially in the sill area, begins to rust, losing its load-bearing capacity. If you notice holes through or severe swelling of the paint, replacement of thresholds becomes an inevitable procedure to maintain the security and liquidity of your Nissan Sunny. Ignoring the problem will lead to rust spreading to the arches and bottom, which will make repairs much more expensive.
Many car owners try to fill holes with putty or primer, but this is only a temporary measure that hides the problem but does not solve it. High-quality repairs require complete or partial replacement of a body element using welding. You'll have to choose between buying ready-made trims or fabricating new parts from sheet metal, and decide whether to do it yourself or leave the job to a professional.
Body condition assessment and preparation for repairs
Before you begin any active actions, it is necessary to conduct a thorough inspection of the car. Assess the extent of the damage: does the corrosion affect only the outer part of the threshold or has it already penetrated inside, destroying the power beam. In the case of Nissan Sunny Often it is the lower edge that suffers, but sometimes the inner cavity also begins to rust.
For an accurate diagnosis, you will need to dismantle the interior trim and, possibly, remove the seats to assess the condition of the metal from the inside. If the metal is rotten through, it will need to be completely cut out. If the corrosion is superficial, cleaning and installing overlays may be sufficient. It is important to understand that surface preparation - this is 50% of the success of the entire repair.
The next step is choosing a repair method. There are two main options: installing overlays over the old threshold or completely replacing the section. The first option is simpler and cheaper, but it does not restore the rigidity of the structure. The second option is more complicated, requires welding skills, but returns the body to its original characteristics. For Nissan Sunny With mileage, a complete replacement is most often chosen to avoid re-corrosion after a year.
Cleaning the work area from dirt, dust and old paint is mandatory. Use a wire brush, sander or sandblaster. Don't skimp on this step, as any remaining dirt under the weld will quickly destroy the new metal.
Tools and materials for work
To perform high-quality work on replacing thresholds, you will need a set of specialized equipment. Without the right tool, it is almost impossible to make a strong and airtight seam. The main unit will be an inverter or semi-automatic welding machine configured to work with thin sheet metal.
You will also need cutting tools: a grinder with metal cutting discs, metal scissors or a plasma cutter for complex shaped cuts. Don't forget about clamps and clamps that will allow you to securely fix the new part before welding. Perforated rivet welding can also be useful for pre-fixing elements.
Materials you will need: new sheet metal (steel 0.8-1.0 mm) or ready-made linings for Nissan Sunny, anti-corrosion compound, rust converter, primer, putty and paint. Pay special attention anti-corrosion treatment internal cavities, since this is where a new process of rotting most often begins.
Don't forget about personal protective equipment: welding mask, gaiters, respirator and protective clothing. Working with metal and chemicals requires caution to avoid injury or fume poisoning.
- Complete section replacement
- Installation of overlays
- Restoration by spraying
- I don't know, I need advice
The process of dismantling old thresholds
Dismantling is the most critical stage, where an error can lead to deformation of the body. Start by removing everything that interferes with access to the threshold: bumpers, wheel arches, interior trim. If you plan to change the entire sill, you will need to cut it off from the body pillars.
Use a grinder with a thin blade to carefully cut away the old metal. Try to make the cuts evenly so that the new threshold fits into place without gaps. If the threshold is welded to the racks, cut it close to the rack, being careful not to damage the rack itself, since this is a strength element.
After removing the main piece, be sure to clean the cut area down to bare metal. Check for hidden corrosion at the mounting points. If the metal of the post is weakened, it will need to be strengthened before installing the new threshold. This is critical to maintaining body geometry Nissan Sunny.
Remove all remaining old mastic and sealant. The metal must be perfectly clean and dry. If you see traces of moisture, let the area dry or use a heat gun. Any moisture under the new seam is a guarantee of rapid corrosion.
☑️ Preparation for dismantling
Manufacturing and installation of new elements
If you do not find ready-made trims for your model, you will have to make new parts from sheet metal. Take measurements from the old threshold or use a cardboard template to cut out the desired shape. Make sure geometry matches the factory one, otherwise there will be gaps.
When installing a new part, it must be pressed tightly against the body. Use clamps and clamps to eliminate play. Before welding, check how the part fits in relation to arches and doorways. Gaps should be minimal and uniform.
Welding is performed using the spot method. Make short seams every 3-4 centimeters so as not to overheat the metal and damage its structure. After welding the main seams, you can go along the entire length, but do not make a continuous seam, as this will lead to deformation. Welding seams must be airtight and durable.
After welding, all seams must be cleaned with a grinder. Remove scale and roughness until the surface is smooth. Then apply a rust converter if there are microscopic spots and coat the metal with an anti-corrosion primer. This will protect the metal from oxidation from the inside.
Secrets of proper welding
When welding thin metal, use minimal current and short pulses to avoid burn-through. Alternate welding points to prevent the metal from overheating.
⚠️ Attention: Do not overheat the metal when welding! Excessive heating can lead to warping of the body and disruption of door geometry Nissan Sunny.
Puttying and preparation for painting
After the metal has been cleaned and primed, the surface leveling stage begins. Apply automotive putty to welds and rough spots. Use a wide spatula to spread the material into a thin layer. Allow the putty to dry according to the manufacturer's instructions.
Then you need to sand the surface. Start with a coarse grit (e.g. P80) to smooth out any rough spots and work your way up to a fine grit (P220-P400). The surface should become perfectly smooth and even. Check the result by touch and visually at an angle.
After sanding, clean the surface from dust and degrease it. Apply acrylic primer in several layers. The primer will fill in minor scratches and create adhesion for the paint. Allow each coat to dry before applying the next. This will ensure the durability of the coating.
Before painting, check the quality of the surface again. If there are minor defects, they can be eliminated with finishing putty or polish. Perfect preparation is the key to ensuring that the paint goes on smoothly and doesn’t fall off in a month.
Before painting, use masking tape to protect glass and rubber seals from splashes of paint and primer. This will save you time on cleaning.
Painting and anti-corrosion protection
Painting thresholds requires care and adherence to technology. Use paint that matches the body color Nissan Sunny. Apply the paint in several thin layers, allowing each layer to dry. Do not try to cover the part in one thick layer, as this will cause drips and uneven color.
After the paint has dried, apply varnish. The varnish will protect the color coating from fading and mechanical damage. Do this in a clean room to avoid dust getting on the wet surface. The varnish should lie flat and shine.
Pay special attention internal cavities thresholds. Even if everything is perfect on the outside, corrosion can begin on the inside. Use special anti-corrosion compounds for hidden cavities, which are applied through technological openings. They create a protective film that is not afraid of moisture and salt.
Complete the work by installing all dismantled elements: arches, bumpers, interior trim. Check how the doors open and close and see if there are any snags. Make sure all clearances are within factory specifications.
| Stage of work | Materials and tools | Lead time (approx.) | Complexity |
|---|---|---|---|
| Dismantling | Grinder, clamps, screwdrivers | 2-3 hours | Average |
| Welding | Welding machine, electrodes/wire | 3-5 hours | High |
| Cleaning and filling | Sander, putty, spatulas | 2-4 hours | Average |
| Painting and drying | Paint, varnish, primer, spray gun | 1-2 days | High |
| Anticorrosive | Special equipment, pistol | 1 hour | Low |
⚠️ Attention: Do not skip the priming step! Without primer, the paint will peel off, and the metal will begin to rust under the coating layer within a few months.
Many car owners are wondering: is it worth doing it yourself? If you have experience with metal and welding, you can save a significant amount. However, if you have never held a welding machine in your hands, it is better to entrust the work to professionals. Errors in geometry or welding can cost more than service costs.
High-quality replacement of thresholds for Nissan Sunny will not only restore the car’s aesthetic appearance, but also increase its safety. A solid body better protects passengers in an accident. In addition, a restored car is easier to sell at an adequate price, as buyers appreciate the lack of corrosion.
The main goal of replacing the thresholds is not just to remove rust, but to restore the rigidity of the body and prevent further destruction of the metal.
Frequently asked questions and answers (FAQ)
How much does it cost to replace door sills on a Nissan Sunny?
The cost depends on the repair method. Installing overlays will cost less (from 15,000 rubles), while a complete replacement with welding and painting can cost from 30,000 to 50,000 rubles, including materials and service work.
Is it possible to use overhead thresholds instead of a complete replacement?
Yes, you can, but it is a less durable solution. The covers hide the problem, but do not eliminate it, and corrosion can continue inside. A complete replacement is more reliable and restores body rigidity.
How long does it take for paint on thresholds to dry?
When using modern materials, the paint dries in 1-2 hours, but complete polymerization occurs within 24 hours. Varnish requires a similar time to gain strength.
Do I need to remove the interior when replacing the thresholds?
Usually yes, it is necessary to remove the inner floor and seat trim to provide access to the inside of the sills and to carry out proper welding and anti-corrosion treatment.
How to avoid corrosion in the future?
Wash the underbody and sills regularly, especially after winter. Once every 2-3 years, renew the anti-corrosion coating and check the condition of the metal. Timely treatment is the best prevention.