I clipped a concrete block at dead slow speed. It bent my rear bumper.

This is the view of the full bumper now. You can see the "knee" I put in it. Bumper "Knee"
The bumper itself has a piece of angle iron running through the center to give it support. It is about 1/2" - 3/4" on each leg,as you can see here: Bent Angle Iron
As you can see in this photo, there is no gap between the angle iron and the fiberglass.
There are small "Stem and Cap" fasteners that hold the fiberglass on to the angle iron. They are not removable. Fibergalss & Iron
I believe that the fiberglass can be mended after the angle iron has been straightened. Here are some photos of the outside & inside. Outer View

Inner View
How can I fix this without damaging the fiberglass any more than it already is?


  • 1
    Which vehicle is the bumper off?
    – HandyHowie
    Commented Dec 13, 2021 at 9:11
  • 1
    If your time has any value, it will cost you more to repair it than the cost of a new one, or possibly a salvage yard. Commented Dec 13, 2021 at 15:53
  • @HandyHowie This is a 1991 Safari Serengeti Motorhome. Not my rig, just a picture of what it should look like. google.com/…
    – Scottie H
    Commented Dec 13, 2021 at 17:44

2 Answers 2


I think it is very unlikely that you can straighten the steel.

I would carefully cut the steel out from the back, get some new steel, weld the brackets back on if necessary, then fibreglass it back in place.

That is what I would do if a second hand replacement is not readily available. It would be a lot easier to repaint a second hand one than repair the one you have.

  • I am not a welder. How do you feel about JB Weld?
    – Scottie H
    Commented Dec 13, 2021 at 17:45
  • 1
    If you can’t reconstruct it just as it was originally, then I would suggest that you look for a replacement bumper. You wouldn’t want the bumper dropping off the vehicle on a busy road because the ‘glue’ failed.
    – HandyHowie
    Commented Dec 13, 2021 at 17:54

You shouldn't attempt to repair a bumper. You will not be able to restore the original performance correctly - remember that its job is to absorb impact in order to protect the vehicle (including occupants) and environment (including other road users).

If you make it too stiff or too soft, you have compromised the safety of the vehicle.

The only reasonable choice is to replace with a new or reputably salvaged one.

  • 2
    You could say that about all car body repairs seeing as car bodies are built to crumple in a specific way in a collision. As long as repairs are done correctly, there should be no issue.
    – HandyHowie
    Commented Dec 13, 2021 at 14:20
  • That's a good point, but I do have a sense that bumpers are somehow special in that regard (perhaps because that's their main/only function, as opposed to keeping weather out and contents in). It seems to me that fibreglass-patching of body panels is less risky than the same operations on bumpers, though I have no facts to corroborate that. Commented Dec 13, 2021 at 15:58
  • 4
    On the vast majority of modern cars, the bumpers are purely cosmetic and not designed to be rigid parts to take impacts like they originally were. This is a good example where a very small incident has only damaged the cosmetic bumper which is easily unbolted and replaced. That thin length of angled steel was giving no real strength to the car.
    – HandyHowie
    Commented Dec 13, 2021 at 16:26
  • I was thinking the likely risk was making it too strong, rather than too weak. As you say, with modern cars it may be a cosmetic piece rather than a real bumper. The last vehicle I had with a proper rigid bumper was a Series III Land Rover; I had to hit a tree head on to get even a slight dent in that! More seriously, front bumpers in particular are now designed to be pedestrian-friendly as much as possible, so be cautious repairing those. Commented Dec 13, 2021 at 17:11
  • I'll look around. These parts are hard to find.
    – Scottie H
    Commented Dec 13, 2021 at 17:46

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