How to Repair a Rocker Panel


 – Method 1: repairing a sill that has been driven in with an inertia hammer (or nail puller)

 – Method 2: repairing a rocker panel with a welding station

 The rocker panel is an element located under the doors and exposed to impacts. One blow on a sidewalk, and it is depressed. Its sheet metal is thicker and less accessible than a fender or hood sheet metal, so its repair requires both expert hands and specific equipment.

 While putty is useful for repairs up to 1 to 2 mm thick, it does not hold in denser areas.

 This post explains how to repair a rocker panel that has been hammered in with an inertia hammer (also called a nail puller) or with a welding station. Without this specific tooling, you will not get a conclusive result!


 Equipment needed to repair a dented rocker panel.

Disc grinder Starting at $40.
Drill Around $2.
Mallet $4 approx.
Welding station Starting at $80.

Method 1: repairing a sill that has been driven in with an inertia hammer (or nail puller)

 The first method of repairing a rocker panel is to straighten the rocker panel by pulling it from the outside with an inertia hammer. Older models welded nails to the sheet metal. Newer models use a star tip applied directly to the sheet metal and produces the same tensile effect as nails.

 Beware, this is a relatively expensive device. Prices can vary from several hundred to several thousand euros, depending on the inertia hammer’s power and precision. There are mechanical nail-pullers, other electrical ones, some, more professional, and three-phase current. You may be able to rent one from a private individual who wishes to make his purchase profitable.

 To repair a rocker panel with an inertia hammer:

 – Begin by stripping the damaged part of your rocker panel, by sanding around and inside the impact.

 – Also strip off another part of the body that is not visible, on which you will place the weight of the unit.

 Adjust the inertia hammer’s power according to the manufacturer’s instructions for the thickness of the sheet metal to be straightened.

 – Apply the nail puller to the depressed rocker panel, while pressing the sheet metal with a bodypack to avoid forming a dent in place of the hole.

 – Grind any impacts left by the nails or star tip.

 – Proceed to the finishing touches: apply putty in several coats to make up for the last deformations, then paint and varnish, with sanding between each coat. For a uniform result, repaint the entire lower body.

 Tip: straightening kits are available with suction cups and glue, but the rocker panels’ sheet metal is too thick to be straightened with this type of material.

 Method 2: repairing a rocker panel with a welding station

 The second method to repair a dented rocker panel is to cut out the dented area on the rocker panel, straighten it on the workbench, and then weld it back in its original place. This is called sill drilling. To do this, specialized tools are required: a semi-automatic Mig/Mag welding station and bodywork tools for straightening the rocker panel.

 To repair a rocker panel with a welding station:

 – Start by removing the door seals attached to the recessed rocker panel.

 – Use a grinder to cut out the recessed area on the sides.

 – Use a drill with a de-pointing bit to detach the underbody portion from the rest of the vehicle.

 – Place the dented underbody section on your workbench and straighten it using the appropriate tools: mallet, pile and body hammer. Be careful; you must control the body for this part of the repair to avoid further deformation of the sheet metal.

 – Tap from the inside to the outside, keeping the bodywork pile on the outside to prevent a dent from forming.

 – Grind the edges of the parts to be re-welded. You won’t be able to weld if you haven’t stripped the paint.

 – Put the straightened underbody in place on your car.

 – Hold it in place with clamps and weld it back together.

 – Grind the welds and apply putty.

 – Proceed to the finishing: apply primer and paint all over the rocker panel.

That’s it. You are now done repairing a rocker panel, which is not an easy task for any DIY enthusiast. If you wish to find a professional, you can get in touch with Melton Smash Repairs located on High Street in Melton.

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