Front Fender Dent Repairs

This afternoon I spent a lot of time doing bodywork on the front fenders. At some point in the car’s life it was clearly involved in a front-end collision on the front passenger side, and the resulting fender repairs left a lot of holes from the slide hammer used to pull out the dents. When I bought the car bondo was spilling through these holes inside the fender, inviting moisture to penetrate the metal under the filler. Also on the driver’s side there was a dent just below the headlight that had been pulled and it required more attention as well.

The first thing I did was to remove any remaining paint and/or filler or seam-sealer from both front fenders, and give them a thorough washing. I scrubbed any residue, grease, or adhesive from both fenders using a brillo pad and some Simple Green. Then I rinsed both well and parked them on the back patio to dry in the sun. After 90 minutes in the July Texas heat the front fenders were totally dry.

I started on the less-mangled driver’s side fender. Here is the dent in the fender and the hole probably used to try to pull the dent using a slide hammer. I used a Clean n Strip wheel in my drill to clean the metal.

With the area cleaned up I used my mig welder to patch the hole.

The welded area I then cleaned by hitting it again with the wheel to remove any scale and then wiping with acetone to get any grease.

The next step was to fill the dent with body solder in order to get it as close to level with the surrounding metal as possible. I brushed on the tinning compound that would enable the solder to bond to the steel.

Then I heated the tin with my propane torch until the impurities burned off brown and black. Those I wiped away with a clean white shop towel.

This left a thin coat of tin that bonds to the steel and the solder bonds to the tin. The body solder will not bond directly to the steel without this step.

Next I started applying the body solder, which comes in rods, by heating the solder and placing dollops from the end of the rod into the dent.

The repair definitely looked rough, but my strategy was to build up the solder above level and then bring it back down with a grinder to make it as smooth as possible. I have found applying the solder smooth when hot to be impossible.

So I used three stacked cut-off wheels in my 4 1/2″ angle grinder to grind away the excess solder to try to get it as level as possible.

And as you can see from the side the result was close to the profile of the original metal, albeit not a smooth surface.

After grinding I wiped the area again with acetone.

In order to get the solder repair smooth I applied a thin coat of body filler on top. I’ve been using Metal 2 Metal filler from Evercoat, which I like a lot. I put a scoop of filler about the size of a golf ball onto my board.

Then I added 12 drops of hardener per the instructions on the can, and gathered the filler on a plastic spreader.

I applied the filler without working it too much on the surface, which I’ve found just makes the surface rough. Once again I applied a coat that would be proud of the final surface so that I could sand it later in order to bring it back to flat and blend the edges into the surrounding fender.

And here is a shot from the side of the repair.

Next I repeated the same process on the passenger side front fender, which was in worse condition. I welded up all the holes used to straighten the fender (must have been a bad dent!) and then cleaned and applied tinning compound.