Suggestions on retrofitting fogs to bumper

General Composites Discussions Composites Talk
#1

Hi,

I’ve been dealing with composites for quite sometime, but with simple designs only… mostly 2 dimensional such as multicolored key chains, stained plastics (like stained glass), and wood lamination (certificates, pics, etc…)

This is the first time I’ll be doing something a bit complex. Here is a pic of a target car (not exactly my car, but its the same as mine). See the area where a dummy insert was placed on the bumper just below the headlight/turn signal? That is where the fog lamps should go.

Here is the fog lamps that i wish to retrofit. Its a hella FF50 fog lamp. http://www.myhellalights.com/halogen_lamps/FF50.html

I don’t want to use the stock fog lamp since I find it too little for use so I got those and plan on fitting it where it is suppose to be.

So far, here were the tasks done…

  • The “dummy thingy” on the bumper was removed and stripped off with paint. ***
  • I have made an oval ring approx 5 mm thick out of PER and 1.5oz CSM that will fit around the perimeter of the fog housing
  • My intention is to create a cut on the middle horizontal line enough for the oval ring to be inserted and use CSM/PER to bind it to the original housing.

*** I found out that this material is a soft plastic material that becomes soft and pliable with “too much” paint stripper. The form was preserved even though some minor surface scratches were left. The “dummy” is still very usable.

Now here are my questions:

  • Given that the housing melted a bit with paint stripper, is there a chance that PER will melt it as well? (There were no markings behind to identify the kind of plastic)
  • Assuming that PER will melt the plastic housing, can I brush the surface with glue, let it dry and start laying out PER and CSM?
  • Is there a chance that PER/CSM will separate from the original plastic housing?

If you have any ideas on how to approach this, please do so. I’ll be glad to hear/read all your suggestions.

#2

Find a wrecked bumper from one of those cars - the same make and model, so that you know the material is the same. Autobody shops should be able to help you there.

Then, I would set up a peel test, bonding strips of fiberglass cloth to the material in question, leaving a part of the strip sticking out from the bond, so it can be peeled up afterward to test it’s ability to hold things together. Prepare the bonding area using different methods, and see what works best, if anything.

First test, no surface prep, leave it dirty, even!

Second test, sand the area to give good mechanical grip

Third test, wipe with acetone

Fourth test, acetone AND sanding

Fifth test - your idea of a glue between the bumper and the PER.

…and so forth…test all the variables you can come up with, let your imagination go wild, and you’ll quickly see if ANY of the methods will work for you.

#3

Or do your tests on the back of your bumper…

If you can’t get it to stick succesfully then try another type of resin (Epoxy maybe) or resort to making it as a seperate component and use mechanical fixings to hold it in place.

#4

thanks for the advices.

the bumper itself (the big thing) is made of a different material from the fog housings. i stripped the paint of an exactly the same bumper and its was made of a harder, tougher material. btw the housings are just fastened by screws behind the bumper. the same goes for the oem fogs. definitely, i’ll be creating a custom bracket for my hellas.

i haven’t thought of your idea of wiping it with acetone then per + fg. if the material will melt a bit with the acetone, the fibers might have the chance of bonding with the melted plastic along with the per. hope it will work.

i’m hoping that i won’t resort to mechanical attachment because i want to make it look like its oem even though its not.

ultimately, the outcome that i am looking at is similar to the oem fogs like this one, but i’ll make it oval shape to fit my hellas

in any case, here are some pics from my work on this project.

here are the two dummy housings, lh and rh. i tried stripping the paint of the right one. the idea is to cut out a segment from the middle rib and insert the pre-cut oval rings made of per+csm and bond it with the original material with resin and fiber as well.

it turned out that paint stripper can melt the plastic as seen from a closer view.

here is how i made the oval rings to fit the hellas.

i placed the hella housings back to back and wound an old carboard material around, building up to 4 layers which is approx 3mm. i then wrapped it with a continuous plastic bag which is taut enough to hold the shape. this is just one layer of 1.5 oz csm. i am going to build it up to 10 layers.