Note: This tutorial is a work in progress rough draft. I will be editing and adding more content and photos soon. I wanted to share this information with you as we I go. Check back often to see what has been added to this lesson.
When it comes to welded on body panels, we need to carefully think about what type of metals are going to be welded, the sectioning locations, and restoring corrosion protection.
Welding is one of the skills which require a lot of practice to perfect. In fact, I hear welding skills is one of the most important skills for a technician to have from shop owners. With that said, passing a welding destructive test one time does not necessarily mean you are ready to start welding on cars, as you do not want one in every three or four welds to be good welds. You want all of them to be good welds. So don’t every be afraid to put a little extra effort practicing.
Other than the skills, there are many things to consider when welding on modern day cars. For example, UHSS and boron should not be repaired or welded. Trying to repair these types of metals may rip the metal and overheating the metal can change the properties of the steel and weaken the metal.
However, this lesson is not about how to weld or the different types of metal. We are going to focus on exterior panels that can be welded, methods to remove and replace the welded body panels, sectioning locations and restoring the corrosion protection.
Repair The Damage First
The first thing you need to do before cutting and replacing a quarter panel or any other weld-on panel is to straighten the damage. This will help realign the structure the part is welded to and provide correct gaps when the new panel is installed. Removing the part before straightening it is a common mistake and should be avoided.
This may be confusing at first, but it’s really simple when you think about it. If you have never replaced a weld on panel, such as a door skin or quarter panel, you may be quick to remove the door from the vehicle and start taking the glass, handle, and whatever else is needed in order to remove the door to replace the door skin. However, this can lead to many problems that can be prevented if you follow this simple step.
Repair Before Replace
I am going to refer to a door skin in this example, but the same rule applies to all weld-on panels. Repair the damaged door skin before continuing to the next step. I’ve had students ask, why repair the damage if it’s going to be replaced? Well, the reason you want to repair the damage first is to realign the door shell. This will allow proper gaps and assure the new skin will fit properly and the panels will align correctly when the door is reinstalled back onto the vehicle you are working on. This sounds simple enough and makes sense, but I have found this to be a common mistake when learning how to replace welded body panels.
When repairing a damaged weld on panel it is not necessary to pull the metal until it’s ready for body filler or try to metal finish it, you just need to rough pull the damage to assure the door closes correctly and the gaps look straight. After this step is performed you can take the door off and continue with your door skin removal and replacement procedures.
If you’re a technician, I’m sure this is a normal procedure for you. However, it you are a DIY or you have never replaced a weld on panel, I hope you find this tip helpful.
What Problem Could Occur By Making This Mistake?
Let’s say that you removed the door skin and you straightened the shell and flanges after the skin was removed. It looks good so you start replacing the new door skin. Looks great when you’re done…that is until you put it back on the car and realize that the shell is a little tweaked. This may result in uneven gaps, the door edge in too far or sticking out too far making it impossible to align properly. This applies for a door skin, quarter panel, or any other panel that is welded on.
Repair, remove, test fit, and install part for welding. This will assure the car will look like it was never involved in an accident, which is your goal.
Tip: Did you know that you can buy reconditioned welders? Check it out to see if they currently have one available. www.CollisionBlast.com/ReconditionedWelders
Tip: When separating panels use a seam buster tool. This tool makes a much cleaner cut without damaging the panel as with an air hammer. www.CollisionBlast.com/SeamBuster
Remove The Part and Hardware
Once the damaged part is pulled and realigned, now you can start the removal process. Remove any necessary items from the panel, such as glass, hardware, or anything else that will need to be removed to gain access to the factory spot welds. You will also want to disconnect the battery and remove any electrical component near (within 12 inches) the areas you will be welding. Once you have everything removed, you can start looking for the spot welds. Spot welds are easy to identify, as they appear to be a small dimple in the metal. However, some of them may be covered with excessive coatings or seam sealer. To remove these coatings or seam sealer, use a wire brush or a brush with plastic teeth that fits onto a drill to remove the coating. The plastic teeth type of tool will not remove metal when removing the coating. Once you can see all of the spot welds, you can begin to drill them out.
How To Properly Use a Drill
I know, this sound self explanatory, but this is another task where many mistakes are made. In this case, more is not better. What I mean is, the higher rpm you set the drill will make the job more difficult.
In order to drill through metal it is important to use low speed when drilling. If using a too high of a speed, you will overheat the drill bit, which will dull the bit making it difficult to drill through metal. In addition to using a lower speed, you should use a cutting oil or paste to help keep the bit lubricated and from overheating.
I don’t know the exact speed, as it depends on the hardness of the steel you’re drilling. Generally, the harder the steel, the slower speed you should use. Therefore, high strength steel should use a lower speed than when drilling mild steel. This speed can range anywhere from 30 to 200 sfm, which is much slower than the speed used to drill wood.
Many drills have variable speeds, which makes it easy to slow the drill down. However, if you are using an air drill, you may need to turn your air pressure down to achieve the slower speeds.
Using A Drill To Remove Spot Welds
There are many different ways to drill out spot welds. However, just a drill a a couple of bits is all you need. Once you have located the spot welds, use a hammer and center punch to strike the center of the spot weld. Place the punch in the center of the spot weld and hit the punch with the hammer. This will create a small indention in the metal, which will prevent your drill bit from walking or moving around on you. Make sure to make the indention in the center of the spot weld, or you may not properly drill out the spot weld. Now that you have punched all of the spot welds, you can use a 9/64 small drill bit to drill through the panels welded together. Next, use a 5/16 drill bit and drill only through the front side of the panel. You do not want to drill all the way through both panels, just enough to drill the spot weld off. Once you have drilled the top panel on all of the spot welds, the panel is now ready to come off. Using a seam buster (a chisel type tool) split the panels apart. You can also use a air hammer, but this tool causes a lot of additional damage . A seam bust does a much better job. Using a hammer, just hit on the seam buster to break to two panels apart.
Using A Spot Removal Tool
There are special tools to help you remove spot welds as well. A pneumatic c-clamp spot removal tool does a great job of removing spot welds on flanges. However, if not by an edge this tool will not work. To use this tool, simply locate the spot weld, place the tool on the spot weld and pull the trigger,. As the trigger is pulled it will also apply pressure at the spot weld location. The tool eliminates the need for a smaller drill bit before using the tool.
Hole Saw Spot Welder
They also make another hole saw type bit for drilling spot welds. This has a sharp pint in the center of the tool to help you align the bit as it drills out the spot weld. I have never had good luck with this tool, as it seams the bit dulls way to fast. Maybe it was just the bits that I used, but they have not worked well for me. However, it is another tool you may consider trying.
Using A Cut-Off Wheel To Remove Spot Welds
Another method to remove spot welds is to use a cut off wheel. When using a cut off tool, be sure to use one of the thicker cutting wheels. The edges of the wheel will be used as a grinder to grind the weld location. This does a good job of grinding out the spot weld locations; however, this does damage the panel being cut off. If you are replacing the damaged panel, this will not matter, as the part will be thrown in the junk pile anyway. However, if you are taking a panel off to reuse for another car, this method is not recommended.
I have always preferred on of the drilling methods, but there have been many technicians that prefer to use the cut of wheel. You can try these different methods to determine which one works best for you.
To perform this method of removing the spot welds with a cut off wheel, first locate the spot welds as you normally would. You may have to remove coating to find or access the spot welds. Once located, use the edge of the wheel to grind directly on the spot weld location. This will grind the outer panel until the spot weld has been ground off or ground enough to pop the two panels apart with a seam buster. Once all spot welds have been ground, you can separate the two panels and remove the outer panel. Care must be taken not to grind into the inner metal surface when using this method.
Using a Plasma Torch to Remove Spot Welds
A plasma torch can also be used for removing spot welds, but I don’t recommend this method. It is easy to damage both panels using a plasma torch. However, the plasma torch can be set to minimize the damage to the underlying panel.
To use a plasma torch locate the spot welds and cut around the spot weld location. You only want to cut the outer panel. Once all of the cuts have been removed, separate the panels using a seam buster or air hammer. Once the outer panel is removed, you will have a little extra clean up on the inner panel, as the weld nugget will still be attached and will need to be ground smooth.
I really don’t recommend this method, but I did want to mention it. This way if someone tells you it can be done this way, I wanted you to know that it can be done. And it may work great for some people, but this method requires more skills and can cause more damage than the other methods.
Which ever method you choose, once all spot welds are removed can begin to separate the panels. You may find that there is adhesive holding the panel on in addition to the spot welds. In fact, most newer cars and trucks are held together with spot welds and adhesives. So we’ll briefly discuss removing adhesive. (That is it for now. Check back for more soon!)
If you suggestions, input or questions as I complete this lesson, leave a comment!