Monday, 07 July 2008 11:38

The Never-Ending Journey to Conquer Rust

Written by Rich Evans
One job that is never ending in the body and paint business is rust repair. Since our love of automobiles started us out in the business, we began restoring anything we could get our hands on. I restored my first car—a 1968 Chevy Nova—way back when I was just a little kid. The first step with every restoration, whether it’s a professional or personal project, is identifying the level of rust damage.
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These days, there is almost no way to begin a restoration project without having a fair amount of rust damage to repair. It is usually the first thing to look for when purchasing the project car. The extent of the rust damage also effects the price of the vehicle. People with more money—professional car builders, for example—can afford to spend more on a car with minimal rust damage that he can turn around quickly.
    An average guy with a family and a garage will usually start with something that’s going to need significant TLC. No matter how much money you have, you may just have to take what you can get. Whether you’re a body shop owner, professional car builder, or Average Joe, this is one skill that you will have to become well acquainted with or your project won’t be going anywhere.
    In the many years I’ve enjoyed in this business in various garages, body shops and my own employees, I’ve watched, learned and performed many rust repairs. I’ve worked with a lot of body technicians over the years and it seems that everyone has their own way of dealing with rust.
    After years of working with rust myself and working with other people’s rust repair techniques, I’ve developed my own personal way of dealing with rust repair. In fact, it’s how I try to teach my employees to fix rust. Some of my employees are older and have been working with cars even longer than I have, but for some reason they still have no idea why I want it done this particular way.

Chevy expert
At Huntington Beach Bodyworks, we get a lot of '55, '56, and '57 Chevy classics because we’ve built a reputation for knowing our way around this particular type of car. I have two of my own and restored countless others.
    First I ground away the damaged area with a grinder and a 36-grit disc. After that, I used some diluted Metal Prep Cleaner. My choice is Metal Ready, because it gently etches the metal, helping the primer adhere to the metal. It leaves a light zinc phosphate coating which helps chemical bonding of the paint, with the extra bonus that it is environmentally safe.
     Next, I began to cut out the rotted area in a circular pattern, which is where my technique seems to differ from most. Almost every employee or colleague I’ve worked beside cuts out rotted areas in square patterns, probably because it’s just easier to cut a square than an arch or a circle.

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    The problem: When welding the new piece back in, the weld has to stop at each corner, leaving a high build at each corner which is time consuming to smooth out.
    Rich tip:
That’s why I recommend cutting out shapes in an arch or a circle. When welding the new steel piece back in, the weld will have a continuous uniform look that will come around and meet back with itself, producing a minimum of filler work and sometimes none at all. We al so save a lot of time in grinding and sanding to smooth out the repaired area.
    Getting back to cutting out our rotted panel, first I make a 1-inch border around the rot to ensure that

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I’ve gotten all the rust, then a few reference marks around the opening. Take a piece of scrap paper and place it over the hole. Next, run a finger over the edges of the hole, with the paper over it, to trace an image of the shape onto the paper. After that, I cut out the shape and traced it onto a sheet of heavy gauge steel. Use a steel gauge measuring disc to determine the gauge of steel needed to cut out a new piece.
    After cutting out the piece, mocking it up and adjusting the shape several times, I finally have fabricated a good replacement metal piece to weld back in. Before doing this, shape the curvature of the piece to match that of the panel.
    This is another potential pitfall. A lot of guys make the mistake of welding this flat piece on a slightly curved panel, like that of a '55 Chevy. Then when they’re done grinding down their welds, tons of filler is needed to rebuild the curve.
    Rich tip: Bondo and other fillers are great for their intended use, but were never meant to replace metal altogether. Always take the time to shape the metal the best you can to match the panel to the original.

 
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Putting it together

  
  
It’s time to place the new piece in the hole and weld it back in. The choice of how to hold the piece in place can be left up to personal preference. Some guys just hold it in place with their hands – a technique I do not recommend!
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    At this point our metal has been completely repaired and I’m very happy with the results. I didn’t  need any filler at all, because I took the time to shape the metal. I then mixed up some PCL Primer and sprayed three good coats. When that was dry, all that was needed was a little 400 grit wet sanding and we’re ready for paint.
    That’s about it. Please keep in mind to always cut in arches or circles and shape the new piece of metal to make a fitting replacement, including the contour of the panel. I’ve explained the different choices for repairing rust and pointed out some of the pitfalls that could be occur.
    I hope I’ve helped you in your projects and I’ll be back next month with an article that I think will pique your interest. Now get back to work and good luck.