[Sandwich]

hi frens
I bought a roof rack for my idiotic italian car but it came with a broken piece in the mail. It's the locking cover, not structural, but I would like it if I can make the lock function, not rattle, and look like a solid piece. Unfortunately this is going to be the most challenging sort of plastic repair possible, with a tiny little tab that attaches a big piece to another big piece.

I MIGHT be able to slide a small piece of sheet metal underneath to give it a bit more rigidity, but that's going to be it. What is going to give me my best chance at getting a solid closure and not immediately shattering the thing upon removal? JB Weld? regular epoxy? Maybe glue down the middle, then an additional bead over the top and bottom of the seam?

 

[Sandwich]

What it's supposed to look like:

 

[Sandwich]

From below.

Above I have the aluminum rail, below I have the steel support.

 

[Jm_]

I don't understand this structure, but: Epoxy putty and shape it as you need with a dremel?

 

[canadmos]

Is that a spring under it?

 

[jonKranked]

that's injection molded, if it's a structural element no repair is going to be long lasting. can you get a replacement from the manufacturer?

 

[canadmos]

Make a new one out of electrical tape.

 

[Westy]

Often there are marks that will tell you the type of plastic. I repaired some plastic bodywork I cracked on my motorcycle when I dropped the dumb thing while turning it around in my driveway. It was thermoplastic and thermoplastic pipe cement did a fine job on it. I added a little fiberglass mesh for reinforcement. The thermoplastic cement actually dissolves some of the base material so adhesion isn't an issue. If you use epoxy I would highly recommend sanding the surface so the epoxy can get some bite.

Either way whatever glue you use should be made for the type of plastic.

Or you could just say fuckit and gob as much hot glue on it as you can.

 

[johnbryanpeters]

Epoxy.

 

[6thElement]

Gorilla tape residue.

 

[Westy]

Get a radio frequency friction welder

 

[Jm_]

Gorilla tape residue.

Winner. Just strip the adhesive off with a razor blade, build up a pile of it, then mold it into whatever shape you need. This will probably last at least 10,000 years, + or - 1000.

 

[StiHacka]

Gorilla tape residue.

A lifetime fix.
Recommended by 10/10 WY monkeys.

 

[Sandwich]

Is that a spring under it?

that's injection molded, if it's a structural element no repair is going to be long lasting. can you get a replacement from the manufacturer?

It's not spring but rather a retention bar for the cap that goes over the metal pieces. The metal bars just swivel, but they do spread of you lift it up high enough.
So, it's not structural in the sense that it supports anything, but it does retain another piece. The lock also closes behind it to keep it closed. I'm shocked at how shitty the locks are, but my glue actionb isn't going to make it less safe.

 

[Sandwich]

Often there are marks that will tell you the type of plastic. I repaired some plastic bodywork I cracked on my motorcycle when I dropped the dumb thing while turning it around in my driveway. It was thermoplastic and thermoplastic pipe cement did a fine job on it. I added a little fiberglass mesh for reinforcement. The thermoplastic cement actually dissolves some of the base material so adhesion isn't an issue. If you use epoxy I would highly recommend sanding the surface so the epoxy can get some bite.

Either way whatever glue you use should be made for the type of plastic.

Or you could just say fuckit and gob as much hot glue on it as you can.

I can't find any marks. There may be some under the rubber bottom, but I don't want to risk breaking it by taking it off.

I have jb weld in my possession, I was thinking of using it because I have it. I may be able to reinforce the "weld" with some sheet metal above and below bent to the right angle. The plastic has a perfect fit, I wouldn't want to sand the mating faces down, right? Maybe just the surfaces perpendicular to the break?

 

[Westy]

I can't find any marks. There may be some under the rubber bottom, but I don't want to risk breaking it by taking it off.

I have jb weld in my possession, I was thinking of using it because I have it. I may be able to reinforce the "weld" with some sheet metal above and below bent to the right angle. The plastic has a perfect fit, I wouldn't want to sand the mating faces down, right? Maybe just the surfaces perpendicular to the break?

Yeah don't sand the two mating surfaces but a non visible side and add extra epoxy there for reinforcement.

 

[Sandwich]

Alright, I'm thinking some plastic epoxy (JB Weld Plastic weld?) and then some reinforcement with epoxy putty. I don't have a lot of room up top, but I think I can make two "arms" that will support the thing from the bottom to keep it from snapping in that direction...if they will bond to the epoxy/plastic...

 

[Sandwich]

either that or maybe a couple of brass rods underneath with a bend in them ___/ to match the curve of the plasticy doodad?

 

[HardtailHack]

You could try some SuperTAC 500, not sure how it would go in full sun on a summer day.

 

[Sandwich]

Grabbed some permatex black plastic cement, whatever that is:

the depot had some, and it seemed the wisest path.

made a bead up on top...was not easy to work with so it looks like shit

And then I did one on the bottom as well. I also used some picture hangers bent to match the shape of the slope as support. Those went on after the initial bead. Everything was "roughed up" with sandpaper to get a better bite.

Final result: it works! I can actually lift and close the little lid without issue, though I'd probably still want to be cagey about how rough I am with it. Should get used rarely so if I'm careful, I think it'll be fine. Thanks for steering me away from JB weld regular unleaded.