Last in, first out is always a good approach
QThanks for sharing your experience and knowledge with the community. I have been a longtime reader of your column, and your other articles in Classic Trucks and STREET RODDER magazines. I have been working on a ’36 Chevy two-door sedan project, and I’m now working on the body metal and panels.
I have a damaged front fender, and with my limited knowledge and experience, I want to limit any further damage I might cause to the fender while attempting repairs. I have attached some photos, and hope that you might share your thoughts and any guidance on how to approach the repair. Ted Chrisostomo
A I’m very glad you have enjoyed my contributions to STREET RODDER and Classic Trucks magazines. It’s a joy for me to help people.
Repairing the dents in your fender should be pretty straightforward. Fortunately, the largest dent appears to have stopped just short of the bead on the fender edge, which eases the job considerably. The basic principle for straightening a dent is
“last in, first out.” If you imagine how the large dent was formed, the fender apparently collided with some stationary object. When they first touched, there was a single point of contact, but as the object was pushed deeper and deeper into the fender, the dent spread out, becoming wider and deeper.
To take the dent out, it’s best to start from the outside of the dent and spiral in toward the center. Since the fender is off the car, it may be easier to work on a bench. Put some sort of padding on the bench, like a stack of towels or a moving blanket, and position the fender so the damaged area is close to the pad and easy to reach from the inside. Rather than striking the metal directly with a hammer, you will have better control if you use a wooden tool to move the metal. I often use a wooden 2x2 for this, cut to a convenient length, perhaps 12 inches long, with one end sanded to a contour that matches the crown of the fender.
You can position a tool like this very accurately, and when it’s precisely where you want it, strike it with a hammer, using just enough force to make the metal move a little with each blow. Work gently around the edge of the dent and you will see the perimeter get smaller and smaller. Keep working in this manner until the majority of the dent is pushed out.
Now you can turn the fender right-side up and continue the smoothing with a hammer and dolly. Most of your work should be off-dolly, so you don’t over-stretch the metal. I can see there is a small crease at the base of the dent, and this may require some on-dolly work to get out. Since the crease is so small, it’s possible that you can get it out with careful hammering, but if it doesn’t come out completely, or if you see that the metal is starting to over-stretch from this hammering, you may need to use heat to get the last traces of the crease out.
If heat is required, you’ll need to get all paint and other contaminants off the metal, both inside and out. I would use an oxy-acetylene torch with a fairly small tip, perhaps a “0” size, and heat an area perhaps 1-inch long to a dull red. This area needs to be hammered while it is still hot, and it is very important not to hit on-dolly, since hot metal will stretch very easily. Work your way along the crease in this manner, until all traces of the crease are removed.
If you over-stretch any area on a high-crown panel like your fender, you may need to use heat shrinking to bring it down. Again, you would heat a small area to a dull red color, and hammer off-dolly. I do NOT recommend chilling the hot metal in any way because that will harden it. Take your time and let the metal cool naturally, which will keep the metal nice and workable. Give these techniques a shot, and drop me a line if you have further questions!
✦ This Chevy fender has some large dents. This month we’ll review some basic techniques for removing damage like this.