Of the many attributes of steel, the major component used in construction of the body and structural members of all but some of the most recent Mopars, one downside of this product is certain: Steel will rust. And if the Mopar you’re driving or restoring is like some of the ones we’ve seen lately, chances are it suffers from a rust hole or two in one of the body or floor panels. Even with the best paint job, a tiny imperfection due to a rock chip or scratch can allow water to migrate to the metal, causing rust, which if left untreated can lead to panel rust-through.

While some car manufacturers got a bad reputation for their cars rusting more than others, in reality it depended more on where in the world the car was located, and whether or not it was garaged, cleaned regularly, and driven on salty roads. In our state of Florida we see some extremely rusty cars from salty coastal locations as well as some surprisingly rust-free Mopars from the inland parts of the state. But as these cars continue to age, even a “rust-free” Mopar is likely to have an area or two that needs attention, and we don’t mean filling the rust hole with a gallon of body filler. We mean repairing it properly, with metal.

To properly repair rust, the rusted area must either be cut away completely and replaced, or ground down and treated, depending on the severity and location of the rust. Minor scaling and pitting on body and floor panels can generally be removed with a grinding stone on a power grinder, while major areas of rust-through and rusted frame or structural parts require completely removing the affected area and welding in new steel.

Either way, the surrounding area must be chemically treated with a rust neutralizer containing phosphoric acid to ensure any remaining surface rust doesn’t reappear through the new paint, causing unsightly bubbles. Depending on the size and number of the rusted areas needing to be repaired, at some point the decision needs to be made about whether it’s less work and expense to simply replace the entire body panel. Of course this method only works if the panel is available for your vehicle, and fortunately companies like Auto Metal Direct offer new panels for most popular Mopars.

Once you’ve decided to repair a rusted area, beware of what you find underneath. Areas like the lower rear quarter panels are welded to an inner quarter panel, which might be rusted as well. If the rusted area you’re repairing is small enough, it’s fairly easy just to cut the section out and weld in a new piece of steel. We get our steel from the wrecked panels piled up behind J D’s Paint and Body Shop, but steel sheet metal is available at most metal or body shop supply stores. A trick we use, especially if the rusted area requires cutting around a body line, is to match up the same shape of the panel with one of the used panels, so we don’t have to shape it so much by hand.

Of course another easy way to fabricate your metal repair patch is to purchase a new panel or just a patch-panel, and then simply cut the piece you need from the new panel. This method saves some time because your body contours and lines should line up properly, but it adds the cost of the new panel to the repair bill. Fortunately, body panels are relatively inexpensive for most of these cars, so we don’t mind spending the money to have the pre-stamped panel we can cut our repair patches from.