Plastic Grill Housing Repair

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bob7four

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My grill housings on my 69 Fish are not a total disaster but do need some TLC. Looking for recommendations to repair cracks that will hold up.
 
On my ‘72 Demon I put epoxy in a groove on the back side. Then buried a heavy wire in it and coated over it with more epoxy. It has held up so far. Don’t know if this will work for you,just what I did.
Yote
 
For a really strong repair...like fiberglass. Both sides connected to each other....or to say, a groove on each side.
 
Do you know the type of plastic it is? Epoxies do not stick well to polypropylene and polyethylene plastics that they use in newer cars. Anyway I have seen repair kits for these plastics using heated wires imbedded into the plastic to hold cracks together. If you use epoxy on any plastic, I would rough up the area with 80 grit paper to give the epoxy something to grip or hold on to.
 
I believe you are talking about the black piece that the egg crate portion fit onto. That can be repaired with fiberglass as I have done it. It's not a ideal situation to only apply to one side but it does work and it doesn't see too much wear and tear. Unless of course there are pieces missing in which case you have a bigger problem. I simply glued the two pieces together with cyanoacrylate (crazy glue) to hold it in place after I roughed up the underneath. Then carefully applied 3 or 4 layers and let it set. It worked fine. The crack is barely noticeable.
 
I will tell you what I did to my 69 Barracuda grill cracks. First, with a 1/16" drill bit, I drilled a hole at the end of the crack. This is called 'Stop Drilling'. It stops the crack from going further. Then I put a decent groove in the crack on the outside part that is visible from standing in front of the car. I folded a piece of 320 grit sandpaper and used the edge to cut the groove. Then I rounded out the edges of the groove for a smooth transition for the filler. You do not want a sharp corner; it will be harder to make the crack disappear when sanding filler. Make sure you groove and round out the 1/16" hole too. Then, on the back side of the grill, you need to reinforce the crack area. I do it with JB weld 5 minute epoxy and woven fiberglass cloth. I use the woven cloth because I like the strength, and I think it is a bit thinner and easier to work with. Scuff up the area on the back about 2" on either side of the crack with 320 grit sandpaper. Then cut a strip of the fiberglass cloth a little longer (maybe 1/4") than the crack and about 1" wide. Then cut a strip of the fiberglass cloth a little longer (maybe 1/2") than the 1" strip and about 3" wide. Then mix up enough epoxy to spread on the scuffed-up area (about 4" wide) and to work into the fiberglass cloth. Better to mix up a bit too much than having to stop and mix up a bit more. First, spread a film of epoxy on the scuffed-up area. Spread enough to soak into the fiberglass cloth. Then lay the 1" fiberglass strip over the crack making sure to try and center it over the crack and overlap the 1/16" hole. Make sure you have a glove on! with a fingertip, and a little more epoxy to the top of the 1" strip and work the strip into the epoxy below it. Smooth it out with your fingertip. You do not want any air in the patch. Then place the 3" wide strip on top of the 1" strip. Once again you will try to center the 3" patch over the 1" strip and overlap where the 1" strip covers the hole. with your gloved fingertip, place more epoxy on the patch and work it in and smooth it out. extend the epoxy a bit past the edge of the fiberglass cloth. Make sure the fiberglass cloth is not dry, but by the same token, don't smear on too much. After the epoxy cures, you can sand the epoxy patch area smooth. Then use some body filler to smooth out the fiberglass patch area on the back and to fill in the crack on the front. Sand it all smooth, apply primer, sand the primer smooth (probably ending up with 400 grit wet) and then paint it. I used Krylon Satin Black. The grills look pretty good and the repairs have held up very well.
 
Many of the old grills were ABS. Oatey makes ABS cement. Or, if you're really adventurous and have a dead keyboard, or unwanted LEGO's, make your own ABS paste with some acetone and an old pickle jar.

Oatey® ABS Medium-Bodied Black Cement | Oatey

Oatey® ABS Medium Bodied Fast Set Black Cement is recommended for all non-pressure applications. The black color easily identifies application to pipe surface. Its medium body has excellent gap filling properties and is easy to apply with included in-lid dauber. This fast set cement can be used...
www.oatey.com www.oatey.com
 
I have fixed many 69 cuda grills. First I’d remove the the plastic grill from the chrome trim and enlarge the holes that the pins set in. The plastic grill shrinks but the chrome trim piece doesn’t which is what leads to the cracking. I then repair the crack and or replace missing sections with a product call Plast-Aid. No reinforcement is needed other than a little overlapping of the material on the backside. The repair is stronger than the original material. One note is that the Plastic-Aid cures very hard and I’ve had to use a Dremel to rough it to shape.
 
Plastic weld it using an old soldering iron with a flat wood burning tip and black zip ties as filler.
 
Deltatech said:
Plastic weld it using an old soldering iron with a flat wood burning tip and black zip ties as filler.
Click to expand...
I have actually done this technique several times since I first saw it on YouTube about a year ago. I think you have a good idea. If I need to do this again, I'll try it. It works very well.
 
The trick to using zip ties as filler is puddeling enough original plastic and mixing it really well with the Zip plastic, when I shape it I use a body dolly, get the plastic just the right temp(juuuuuust enough where it will compress) and mush it flat with the dolly.
You can just push hot staples in the plastic to hold a bad crack together enough to fill it.
PLastic welding isn't common knowledge and a lost art.
 
The lower corner of this guage cluster was missing and has been filled in this picture, after this I heated it and flattened the filler plastic then dremeled it to almost perfect shape.

20190326_185331.jpg
 
Deltatech said:
The trick to using zip ties as filler is puddeling enough original plastic and mixing it really well with the Zip plastic, when I shape it I use a body dolly, get the plastic just the right temp(juuuuuust enough where it will compress) and mush it flat with the dolly.
You can just push hot staples in the plastic to hold a bad crack together enough to fill it.
PLastic welding isn't common knowledge and a lost art.
Click to expand...
This is what I got from harbor freight to fix a badly cracked bumper cover on my Dodge Journey. It worked great. I drove it in bad weather conditions and it hasn't cracked again. First time I used it and it worked easy. I bought some extra plastic welding rods and I don't think I even had to use them. It doesn't take much!
80 Watt Iron Plastic Welding Kit
 
One quick way to fill a big crack or even hole in plastic is to use glue gun but use plastic rods or zip ties insted of glue sticks.
 
JDMopar said:
@partsmonsta restores Cuda grills, so maybe he will chime in. :thumbsup:
Click to expand...
Thanks for the plug, but we quit doing the 69 Cuda Grilles since they came out with the repro.
Customers kept sending the repro stuff with the OEM and they don't interchange. It was a major nitemare for us.
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90% of our work is the 67/8 Grille/Panel Cuda stuff now.

68-CUDA-BART-01.jpg


Dan Belanger 67 Cuda.JPG
 
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