How do you glue these back on?

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That may be the worlds strongest bond like is says on the package, but bonding the plastic back by melting its original material back into one another cant be beat especially in areas where you cannot add thickness like an A pillar moulding. I have used an aluminum paste version of JB Weld fixing more sections of these grille pieces shown in prev posts as well. It works well in some applications just needs a good scuffing to get it to adhere.

I have also bonded 1/16" thick polycarbonate sheet behind repaired cracks with MEK and clamps to hold it till dry. Being that the MEK melts the plastic fusing it back together to its original state its just a better bond. See pix below for bonded doubler over back side of repaired crack.

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Broken w missing piece is a perfect place for JB weld to be used as a filler. Sometimes these types of repairs need to be done in multiple steps, letting everything dry between steps. I had a corner broken on one of these grilles. I had to use JB weld, MEK, and polycarbonate to repair. See below for start of repair
 
The first part was to rebuild the curved part. Once i scuffed it up to accept the jb weld, i made a mould with a piece of polycarbonate and some release film tape. Clamped it into place and filled in the missing piece with JB weld. Once dry i sanded it to shape.

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Second part was to fashion the missing lip out of polycarbonate. I only had 1/16" and the lip was 1/8" thick so i glued 2 pieces of polycarbonate together with MEK, clamped thrm together and let dry, then shaped the new piece to fit and installed w JB Weld. Notice it is not filed to final shape on the ends yet, but it basically a trapezoidal block at this time.

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Final shaping to make the curves after its dry, and ready for primer. Notice how i added more jb weld and feather edged it into the base plastic.

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I think what helps is i was into model making as a kid, specifically scratchbuilding different kits that werent available, plus doing autobody as a hobby since i was 15. The surrounds will get sprayed w dupont sandable laquer primer. Yes it does eat plastic, however if sprayed in very fine coats letting it dry between coats it will etch into the plastic nicely without cracking or crazing. This makes a nice base to sand smooth and apply topcoat to. I will leave them in primer and let my son decide on black or silver.
 
I got a couple more. The upper headlamp cutout area on these is notoriously weak. I glued the pieces together, however slight flexing and they will break. I made doubler angles out of .016" 301 1/4 hard stainless steel sheet because it was nice and thin, yet very strong. Plus concidering its working 3nvironment, it wont rust. Adding the 90° angle to it stiffened it right up. I then sandblasted the bonding side of the stainless to rough it up. I ground the plastic back slightly , and sanded it with 80 grit sandpaper to rough it up so when the doublers are installed they bond well and are keeping the part at the same dimensions to fit flush back in the grille opening. Then with JB weld and a bunch of clamps i clamped it into place. This was done to both surrounds.

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Had a deformed corner, decided to bond what i could with MEK. This spot was previously glued with super glue. And was missing a piece. I cleaned off the super glue with a razor knife and got enough to bond. Then i fitted a straight spare grille trim and clamped it. This resulted in the plastic cracking somewhere else in the corner. I half expected it to do that, so it could relieve the stress in that corner. Then i removed the trim. Brushed on a small amount of dow corning DC33 O ring lubricant to the back side of the chrome trim as a mould release, stuck a piece of shrink tubing over the trim stud, and packed the corner full of JBweld. Once dry i popped the trim off, and will final shape, and sand the corner to shape when i have more time.

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I hate to kinda take over moparmandans thread, but theres lots of ingenious ways to use these repair products like JB weld, and MEK to fix major parts. I hope my replies help some folks who need to fix this stuff.
 
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The cost of $750 for repop plastic surrounds was the big reason for doing this. I bought a header panel with broken grilles bolted in it along with a cache of 69 cuda parts for my sons car. The broken grilles stayed in the header because i wasnt sure how i was going to fix them, and the fact that i wasnt going to just remove some good parts off them and pitch em. The whole pack rat mentality i guess lol. The biggie was the $750 though.

I figured i got more time than money. Couldent hurt em any worse than they are. Honestly though, if the new ones were $150-$200 for the pair, i wouldent have bothered fixing these. 50 year old plastic is brittle as hell. I dropped one of em, had to glue it back together all over again in different places. These pieces are fine once assembled and bolted in the header, but until then need to be treated with care.
 
moparmat2000 said:
The cost of $750 for repop plastic surrounds was the big reason for doing this. I bought a header panel with broken grilles bolted in it along with a cache of 69 cuda parts for my sons car. The broken grilles stayed in the header because i wasnt sure how i was going to fix them, and the fact that i wasnt going to just remove some good parts off them and pitch em. The whole pack rat mentality i guess lol. The biggie was the $750 though.

I figured i got more time than money. Couldent hurt em any worse than they are. Honestly though, if the new ones were $150-$200 for the pair, i wouldent have bothered fixing these. 50 year old plastic is brittle as hell. I dropped one of em, had to glue it back together all over again in different places. These pieces are fine once assembled and bolted in the header, but until then need to be treated with care.
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Hey Mat, I went to buy MEK at Lowes and all they have is MEK Substitute. I didn't want to waste $10 on it. Who else carries the real deal?
 
So I tried the MEK substitute and it seems to work fine. I had to encapsulate the one in the upper left. The po had already tried to glue it back with JB Weld so the MEK wouldn't work.
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Using MEK:
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Sorry i didnt reply earlier about the MEK substitute. I never got an alert from fabo. Sometimes that happens my favo homescreen wont ahow all my alerts. I am glad it worked though.
 
moparmat2000 said:
I hate to kinda take over moparmandans thread, but theres lots of ingenious ways to use these repair products like JB weld, and MEK to fix major parts. I hope my replies help some folks who need to fix this stuff.
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Hey Mat you ever try MEK on a taillight lens? Not necessarily a crack but I have a couple chips on the painted silver parts. Like around the back up light lens.
 
I have glued em back together with MEK, then wet sand em smooth when its dried for a week or so. Never used it on chips.
 
I have used the mesh Sheetrock tape on the back sides of plastic repairs. If you can embed in in your glue, it makes repairs a lot stronger. It has a little adhesive on it so it will stick in place if everything is really clean.
 
Most of those automotive plastics were ABS so use MEK to glue, if you need to fill, use ABS cement from a plumbing store, it's usually a thick gooey grey semi liquid melted ABS, I use it to build up around studs that have broken off making it stronger than OE when dried, and you can sand to shape if needed as it's essentially the same material you're trying to fix.
 
If using the MEK on a cracked piece that is oily. Can you use brake cleaner then after it's dry put the MEK on it?
 
Brake cleaner will likely melt the part and destroy it. Use a sink full of hot water and liquid dish soap like Dawn to soak, scrub, and remove the oil from the parts to be glued, dry thoroughly, then use the MEK.
 
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