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Bumper Cover Repair - How to Repair Broken Slot Tabs
This video will show you how to repair those "slot tabs" that are very common on bumpers. "Slot Tabs" are those rectangular slots on the edge that snap into the brackets on fenders and quarter panels. Often, these can break when you are removing the bumper. They are hard to repair using two-part adhesives since they present so little surface to stick to.
This video will demonstrate how to repair a slot tab with the nitrogen plastic welder.
Our Bumper Pliers Kit is a great tool for easily repairing slot tabs with the nitrogen plastic welder. It comes with a variety of dies to fit different size slots. Watch our video on our Bumper Pliers Kit here.
Always wear proper safety gear while working!
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Note: This is a list of the Polyvance products that can be used to make this repair. This list does not include sanders, grinders, or other common tools you will need. If you have any questions, please don't hesitate to call technical support at 800-633-3047.
In this video we will show you how to repair one of the "slot tabs" that are very common on bumpers. These are the rectangular slots on the edge that snap into the brackets on fenders and quarter panels. Often, these can break when you're removing the bumper. They are hard to repair using two-part adhesives since they present so little surface area to stick to. There are many sizes and shapes of slot tabs, but two common styles are like this - one where the flange is straight and one where the flange follows the contours of the slot. We will repair both using different techniques.
First, cut out the bar going across, even if it's only broken in one place. The repair will be stronger if you cut the bar out. For straight flanges, you can use a piece of narrow ribbon that you have cut down to match the width of the bar. Using a die grinder or Dremel tool, taper the bumper down on either side of the slot at least three-quarters of an inch. The plastic should be very thin at the edge of the slot. Use aluminum tape or a paint paddle covered in aluminum tape to support the melted welding rod as you make your pass over the gap. Here, we'll use the tape-coated stick and clamp it to the flange.
Starting on one side, begin the welding process by pre heating the bumper and the rod for a few seconds. When you touch the rod down and it sticks, you're ready to weld. Focus the heat a little more on the rod than on the bumper, since the bumper is so thin here. The rod should fold down naturally as it gets to the right temperature. When you get to the gap, continue to weld directly across, just as if you were welding onto the bumper. The aluminum tape underneath will support the plastic. Pick it up on the other side by, again, pre-melting the bumper and continue welding until you reach the end. If the plastic is a little low in the middle, you can immediately come back and do a second pass. Notice we'll just weld across the gap and that we are focusing nearly all of the heat onto the rod, since the plastic we just laid down is already nearly melted. While the plastic is hot, use the hand seamer tool to flatten the weld. This will help to mold it to the same thickness as the flange. Press gently for a few seconds. This tool will help to cool the weld so you can handle it right away.
Remove the backing support. It is very important to get the dimensions of the slot and the flange thickness the same. You can use a razor knife to trim the edge, and you can use the hot airless welder to shape the slot and smooth it out. Look at the backside of the flange where you should still be able to see the original dimensions of the slot.
A one-sided repair should be plenty strong to hold the bumper in place; however, if you want to get the ultimate strength, repeat the same process on the bottom. V-groove into the bumper on either side of the slot and also across the bottom of the bar you just welded on. This time we'll use the round rod to lock into the welding rod on the other side. Pre-melt the bumper and the end of the rod. Touch the rod down and keep the heat focused at the point where the rod meets the bumper. We'll focus a little more heat on the rod instead of the bumper, since the bumper is so thin here. Go right across the bottom of the bar you welded from the other side. This will help lock the repair into the bumper even more strongly. When you finish the weld, smooth it out with the airless welding tip. Just a side note: be careful when you're welding very thin plastics - the base material may lose its structure if it gets too hot. If that happens, just back off, let it cool a bit, and then come back later.
Now we'll repair a slot tab where the flange follows the curvature of the slot. Here, we'll use the round rod since it can make curves a lot easier than the ribbon can. V-groove into the plastic deeply with a sharp carbide burr like our part number 6125. We'll want to make a deep v-groove right to the edge of the slot. This is what gives us strength across the gap. Because we're not disrupting the original structure of the rod, it maintains its original strength. Continue the v-groove on both sides of the slot. Remove the burrs and also remove the paint from the edges of the flange, so that the welding rod will stick to it. Support the melted welding rod by using our 6485 aluminum body tape on the back side. You can use a couple of layers of tape to make the foundation stiffer.
Using the round polypropylene rod, pre-heat the bumper and the end of the rod. We will direct more heat onto the rod, since the bumper is so thin here. Note that the angle of the torch to the bumper is almost flat. Apply a steady downward pressure on the rod and it will fold down naturally as it reaches the right temperature. Weld right across the gap on the aluminum tape, just as if you were welding to the bumper. Pick it up on the other side and continue to weld all the way to the end. Reheat the rod until it turns translucent, then lightly squeeze with the hand seamer to get the repair to the same thickness as the flange. Peel off the aluminum tape and then use the hot welder tip, a razor knife, and a rotary tool as required to reshape the slot and the flange. DA the plastic to get it to the final shape.
Test the strength by pulling on the tab. A one-sided repair will have plenty of strength for this. The tab is not meant to be bent on its application. If desired, you can further strengthen the repair by welding on the backside as we did previously. Make a second pass over the middle of the slot if necessary to fill it out. You can smooth the plastic and shape the slot with the airless welder tip. A final strength test, and you're ready to go.