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How to Repair a Cracked Bumper

Created on: 2019-05-30

Be your own auto body! Learn how to repair a cracked bumper cover with fiberglass and then repaint it yourself! Watch this video to see how to do it.

  1. step 1 :Securing the Bumper Cover Crack
    • Check the crack in the bumper to see how well it meshes together
    • Sand the area around the crack on the rear of the bumper cover
    • Sand the plane of the crack in a V shape to accept fiberglass material
    • Clean the sanded areas
    • Line the crack up
    • Tape the crack together on the opposite side to hold it in place
    • Cut the fiberglass material to size to cover the crack with overlap
    • Mix fiberglass resin following the instructions on the container
    • Apply fiberglass resin to the crack and the surrounding area
    • Apply a layer of fiberglass
    • Apply resin to the layer of fiberglass
    • Repeat for as many layers as necessary
    • Allow to dry
    • Remove excess material
    • Remove any tape
  2. step 2 :Filling the Crack in the Front
    • Stand the area around the crack
    • Fill and smooth the area with fiberglass body filler
    • Sand the body filler
    • Smooth the area with finish body filler
    • Sand the body filler
  3. step 3 :Painting the Repaired Area
    • Mask off areas of the bumper cover you do not want to paint
    • Scuff the paint area
    • Apply primer
    • Apply matching paint as necessary
    • Apply clear coat as necessary

Tools needed

  • Angled Die Grinder

    Surface Prep Discs

    Duct Tape

    Painter's Tape

    Dust Mask

    Safety Glasses

What's up, guys? I'm Andy from 1A Auto. In this video, I'm going to show you how we're going to repair this crack in this bumper. We pulled the bumper off and we're going to repair it from the back side. If you need any parts for your vehicle, click the link in the description and head over to 1aauto.com.

We want to check this crack out. The best thing to do would be try to get this to line up as best as possible from the front side. There is an area on the bottom here that's popping out. Try to get that like that. Just take a look at it from the back side. Make sure you can access everything, and we have good access back there, which is good.

The first thing I want to do is make sure from the back side that everything seems like I can put this together like it's going to actually mesh together after doing this before doing the repair. It looks pretty good, so what I'm going to... first step, I'm going to take and use one of these sanding discs and a die grinder. I'm going to make sure I wear safety glasses and a mask, and I'm just going to grind about two inches on each side of the crack and even in the crack a little bit just to roughen up the area a little bit.

We're sanding this down because we have a fiberglass repair kit that we're going to be using and we want something for the fiberglass to stick to to make sure it sticks really good. There'll be other kits out there that won't use fiberglass. Some may use epoxy or some screens and stuff, but they're probably still going to have you sand down this area.

The area is where the sanding disc was a little bit too big. What you can do is take one of the sanding discs and actually take some scissors and trim it down to a smaller size and then get right in there. Makes it a lot easier, and then you also want to try to sand a little bit of the crack itself. Get some of that out of there. You want to try to shape it kind of like a V so that some of the fiberglass resin gets in there.

Now, I want to clean this with some acetone and some rags. Wipe it up, and then clean the front side with some acetone. Wipe it up, make sure it's nice and clean. Now, what we want to do is line the crack back up, make it look as natural as possible. Now, if it's a bigger crack, what you could do is drill a couple of holes and then take some wire ties and make it real tight and then we could do the repair and then you cut those off afterwards. This is still attached down here, so I'm not as worried about that. Right now, I'm just going to take some tape and tape it together as good as possible. Holding this together real tight, take the tape, tape it together.

That's on there pretty good. If you want to you can take some stronger tape and tape it on there so it really stays together good, but I would definitely use masking tape over the crack. Now, we're going to flip it back over. Everything looks good. It's lined up nice on the back side. I'm just going to wipe it one more time with acetone. It's probably all set, but it doesn't hurt to wipe it one more time.

Our kit comes with this fiberglass cloth that we want to cut it in strips before we actually start mixing the resin because you only have so long to use it while it's drying. We're going to try to get this mat about two inches from the crack on both sides, so that looks about good. Go right there. We're just going to cut several pieces of this first. Now, you're going to want to follow the directions on your resin. You mix with this and you mix one ounce of resin with 10 drops of the hardener. Set that aside. I'm thinking I'm going to use two ounces. I don't think this is going to be enough, so I'll mix up two ounces. Like I said, just follow the instructions on the bottle. There's two ounces. One, two, three, four, five... 18, 19, 20. Now, I'm going to mix it up. Just going to use a wooden paint mixer.

This mixed up pretty good. Now, I'm just going to take a paint brush and I'm going to try to get deep into the grooves of where the crack is. Try to force it into the crack. Now, we're going to take these pieces of fiberglass and fit them in. Now, this is what's going to give it strength, so we'll layer these up. Take the paint brush, go back over it. Now, I'm just going to keep repeating this step until I feel like it has enough layers on here. Probably about four times, probably about four layers, and use your best judgment of how many layers.

I can trim this a little bit if I need to. Should have cut this one a little thinner. This does a number on your scissors, too, so make sure you don't use good scissors because they're probably going to be ruined afterwards. You want to make sure you're in a well-ventilated area while you're doing this, and also make sure you wear some gloves while you're doing this. You don't want any of this stuff to get on your skin.

There was an area right here where it was cracked on this grill area, so I did put some resin in there and a little bit of the fiberglass sheet, and I'm just going to take these locking pliers, get it lined up how I want it, and lock it on. Hopefully they don't stick to it when I'm done. Just like that. Then, once it dries, it should be all set. I put about four layers of the sheets on here, so that seems pretty good. They're thick. It should hold nice. Now, just let it dry and do its thing.

Now that we let this sit overnight, it takes about two hours to dry, but we let it sit overnight, and I did patch up these two areas, too. There was some cracks there and I used some wire ties to position them in the right spots. We can take these locking pliers off. They didn't stick to that, so that's good. What I could have done was put a little piece of paper in between here or even plastic. I thought of that afterwards, but it looks like it stayed secure and that works out good. Just going to cut these wire ties just using some wire cutters.

Just going to use a utility knife to cut off any of the excess. You're not really going to see this from the front of the bumper, so it's not crucial, but I just want to clean it up a little bit. Cut off some of this excess. If it's too thick, I can use some type of grinder and cut it off. Be careful when you're cutting this stuff. You don't want to cut yourself, but this stuff is pretty strong. Well, that's good to know that it should hold up pretty good.

That looks pretty good. You're not going to see this from the front side, so I don't have to clean this up any more, and because there's no bare metal or anything, I'm not going to have to spray this or anything. It's not going to rust. That's fine. I can flip the panel over, we can take our tape off, see how it looks on the front side.

This came out pretty good. If you look at the crack all the way around, it's sealed up really good. Now, if you wanted to make this a lot stronger, the right thing to do would be to sand this down and then puts some sheets of that fiberglass and do the same thing as the back side on the front side, but it's going to raise it up. It's going to take a lot longer to make this smooth. You'd have to go out further, so what I'm going to do is just sand down along the crack and I'm doing to use some body filler that has a fiberglass in it and we'll do it that way.

Now, I want to sand down this crack. I'm going to us some of these sanding discs. We actually sell a kit of these at 1aauto.com. These work really well with your die grinder. You can use some other type of grinder or you can try sanding it down by hand. It's just going to take a lot more effort. I am going to wear a mask.

Take some acetone and wipe this off. If you have anything that's raised up or high, you're going to want to cut it off. You can use a razor. I'm going to mix up some fiberglass body filler. I have the hardener right here. Take the air bubbles out and just work it around. Follow the directions on the can that you have, and then I'm just going to squirt this hardener on just like that. Now, I'm going to mix it around. I'm doing this on a cardboard tray and I just taped some plastic to it because you're not supposed to it on something that's porous. Generally, I still do it on cardboard, but for the sake of the video, I'll do it on the plastic. Just mix it all together. You don't want to stir it up, you want to mix it like this and you want it all one color. It should turn like a brown color.

Now, I'm just going to take it and press it in. Just put a thin coat on. Oops. You have to move pretty quickly with this. This only takes about 10 minutes, maybe 15 minutes to dry, so try to smooth it out as much as you can. The more you smooth it out, the less sanding you're going to have to do, so it's just like icing a cake. That looks pretty good. I think I'm going to let that set up, and then we'll sand it down.

Now, I'm going to use some sandpaper on a sanding block before this gets too hard and sand this down a little bit. It's easier to sand it when it's a little bit soft. I probably should have waited a little bit longer, but it's okay. We'll let it dry another minute. I'm using 80 grit sandpaper with the sanding block. Good idea to use a dust mask while you're doing this. You don't want to breathe any of this in. Do that. Also, if you're outside doing this, you could put a fan next to you and have the dust blow away from you. When you're sanding on a plane, just keep the sanding block flat, going one direction. You can go in crosses, back and forth, up and down, and then go to the next plane and do the same thing. That's how you're going to get your corners nice.

I'm spending a lot of time with the sanding block, and the more time you spend the better it's going to come out. There's some tiny pinholes. I'm going to go back and fill those with some regular body filler once I'm done, once I feel like it's sanded down enough. Wipe it with a little bit of acetone. Now, I'm going to put some of this body filler on, just mixing up the hardener. Just take the air out of the hardener and just mix it up a little bit. You're supposed to do it for a minute or two. We'll just take a little bit of this, a line across like that. We'll mix this up. Once this is one color, then we can spread this on. I'm going to spread this a little thinner than I did the fiberglass filler.

That's mixed up pretty good. Just spread it nice and thin. This is just for the little pinholes in some of the sanding lines. Once you're done spreading that, take the spreader and just push it down like that, and then when this hardens you can just peel it off. You don't have to clean it. Now, this is nice and dry. I let this dry a little bit longer than I did the other body filler because now I'm going to use this sander. This is a DA, or dual action sander. It doesn't spin, it just like oscillates, so it's pretty safe to use. Still, be careful when doing this. I'm going to sand this down, try to make it even.

Now, if I was trying to be a little more picky, I could sand it with a hand sander, sand it down and then give it a couple more coats or another coat of the body filler, but I'm just going to make it look pretty good just with this.

Just trying to feather it out a little bit so that it's pretty much an even surface across the whole thing, so sand down even some of the paint over here and over here. That actually looks pretty good. It's pretty smooth. I'm not as concerned with the bottom. You're not going to see that as much for the top, so I'm not going to spend a lot of time on that. That's all sanded. Just take a blow gun, blow it off. You're going to wipe it down. Use a little bit of alcohol. At this point, we're ready for primer. We're going to prime this area right here. Now, the paint that is still there, you can take a scuff pad and scuff it up a little bit and that'll make the primer and paint stick to it a little bit better.

Now, I'm going to mask off the area that I don't want to get paint on or primer on. It's a good idea if you have a body line to go up to a body line. It's too bad there's no like line right there or anything. I'm going to do the best I can with the paint that I have. It's not a perfect match for this color, but it'll do. Now, I'm going to prime this. There's many different types of primer. They do make specific primer just for plastic and other types of metals and stuff, so make sure you use the right kind of primer, and then we're going to leave this in a can to let it warm up. Follow directions on the can as far as temperature-wise, and then we'll just prime this area right here. Make sure it's in a well-ventilated area. You should wear a special mask while you're doing this.

I'm going to let that dry, but I am going to move my tape line. Luckily, it didn't go up to the line, so I'm not going to get a line... maybe a little bit right there, but that's okay. What I'm going to do is I'm actually going to move this down a little bit because I want to blend the color a little bit further.

Now, I'm going to do the same with the paint. Leave it in a bucket of warm water so it warms the paint up, and follow the directions on the can. I'm going to paint this. Now, like I said, the color is not exactly what the color of the car is, so I'm just trying to blend it the best I can. Now I'll let that dry and give it another coat in a little while.

That came out pretty good. I put about three or four coats on there. Now, I'm going to put a clear coat on it. Everything is dry. My tape line is back a little bit more. I sanded that down a little bit. Just blend it the best you can, then I'd do the same with this can, put it in a bucket of hot water. Let it sit for a while. Shake it up, follow the directions on the can.

That came out pretty good. You can't even tell where the crack was. It would be nice if the paint matched a little bit better, but for the age of the vehicle, it's going to do. This is one way you can do it yourself.

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