How to Spot Bad Body Work and Hidden Rust
If you’re driving a beater car around, bad body work or body flaws isn’t really going to worry you too much. But if you’re driving a classic car, building a show car or looking to buy something with minimal surprises down the road, bad body work and body flaws can ruin your day once they’re discovered. Some of the things you’re looking for here is bad prep work or rust under the paint, body panels that have been worked to hide collision damage, and body filler that’s been used to hide dents and dings, or collision damage that someone was too lazy to repair properly.
Spotting Rust That’s Been Painted Over
No matter how old or new the car is, rust is your number one enemy, but this is especially true with older cars. Luckily, it’s pretty easy to spot. If it’s bad enough, you can spot it quickly just by looking closely. You can also lightly run your hands or fingers over the body and feel for rough spots or bubbling in the paint. Simply painting over rust won’t stop it from spreading and the paint will only look good for a short time before the rust starts pushing through again. Likely places to find it are around trim pieces, windows, wheel wheels, rocker panels and body joints.
Spotting Shoddy Body Work Using Body Filler
Body filler is probably the most misused product there is when it comes to body repair. Now there’s nothing wrong with body filler itself and is a necessary product for filling in low spots and fixing small imperfections in your body panels but if you build it up too thick (like packing it into a dent) then over time it can crack and ruin the paint.
Some collision shops cut corners to reduce costs and will use body filler (commonly known as Bond-o) to fill in dents and dings. I’ll grant that it’s much easier to strip a section of body down to bare metal and pack some body filler in than it is to get out the body hammer and dollies and reach behind and put in the additional time to work the dents out properly. But far too many “body repair technicians” will do just that. These hacks will slap body filler in dents and dings, let it dry, and then sand it “smooth” before painting.
Spotting their work is usually fairly easy if you look really closely. Unless they use extremely fine grit paper when they sand the filler down, it’ll leave scratch marks in it which you can see if you take a close look under good lighting. Look closely enough, and you can see light scratch marks in the paint under the clearcoat. This works great for around windows, trim pieces, and body joints. You can also look for cracks in the paint, since old paint will glaze and fade instead of cracking. Old filler will crack.
Another way to spot the use of body filler is with a piece of paper and a magnet. Body filler is made with fiberglass and as such is non-magnetic. Find yourself a smallish magnet that isn’t very strong. Place the piece of paper on the body panel to be checked and place the magnet on it. If it sticks, you’ve got metal. Next, slide the piece of paper around the panel, trying to cover the whole panel. If there’s body filler under that paint, your magnet will fall off.
One of the tricks that most body repair techs use is to drill small holes in the metal and then use a body puller (mechanics call them slide hammers) to pull the dent out. This is completely acceptable. However, what’s not acceptable is to get most of the dent out with the puller and then fill it with body filler. The sheet metal should be pulled out so it’s close to the surface of the car with a contour as even as possible. Those small holes from the slide hammer need to be welded shut before applying body filler or else moisture will eventually get in underneath the filler, cause rust and ruin the paint job. An incomplete fix like this can be spotted easily by looking and feeling behind large panels. The filler will seep through the holes and create small (or large) “bumps” on the inside of the panels.
Spotting Shoddy Metal Work
Often times you’re going to find body work that was performed by a tech that didn’t have enough experience working metal and hanging panels. For this, you’re going to have look closely again and start looking underneath the car and in the trunk.
Slowly walk around the car with you finger in the joint between panels (you can also use a dial indicating micrometer if you have one). You’re looking for gaps between panels that are of varying width. Or whose width is different from the matching panel on the opposite side of the car.
To spot terrible metal work, you need to have a pretty good eye and know what the lines of the car you’re looking at should look like. Look at the wheel wells especially. The curvature should match exactly on both sides. Measure from the bottom of the wheel well to the frame rail on both sides.
Getting a completely wave-free body panel after the car is in an accident without replacing the panel takes a real pro. By gazing carefully down both sides of the car length-wise along the panels, you should be able to see all but the smallest waves in the panel. Look along the sides and across the top.
If you’re buying a classic car, you’re going to want to inspect it closely. This means checking in the trunk under the carpet and plastic trim pieces. Run your hands on the inside of the body panels and feel for obvious dents and dings. While you’re doing this, check the seams for evidence of rust. If the owner screams, take your money elsewhere.
These are the easiest ways I’ve discovered to determine if slipshod craftsmanship has been used to repair body damage without doing some major disassembly. And I’ve only touched on the most obvious areas of the car. If you’re performing a pre-purchase inspection, chances are this is the best you’re going to be able to do. If you’ve got a really copacetic owner, you can start removing sill plates and door trim panels to do a deeper inspection, but I’m guessing that these will have to wait until you shell out your cash and get the car home.
About the Author
Gearhead Diva Purveyor of the illest car stuff on the net, decreaser of stance and performance suck world-wide, proud superfan of mods and now recommended by 4 out of 5 people that recommend things.