Repairing broken plastic on side tow mirror


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Thoughts on how to go about fixing a broken out chunk. See’s the bottom left. Of the outside not the cracked mirror. I have two part epoxy and some graphite to make it black.
I don’t have the missing pieces.
In my opinion this will be a very difficult repair to make. I don’t think I would use epoxy though as I feel it would fail with time. My belief based on my experience with doing plastic repairs is the epoxy would not flex, nor expand the same as the plastic leading to an eventual failure. You also are not going to match the texture of the existing plastic. Having said that if you still want to try epoxy use some type of reinforcement, either drilling and pinning into existing or else melting into existing plastic and then casting the epoxy in place on the part. If you are sure you want to attempt a repair I think you’d be better off to try using a plastic welder. You could embed a wire “mesh” backer on the inside edge of the mirror housing and then layer plastic on top of it. I think about midway I’d also embed a second mesh screen. Then build up until you are flush with the existing surface. To finish it off I’d probably even put some of those “w” shaped wires melted along the outside seem. The texture though is going to be quite horrid. You can sand the repair smooth but it won’t match the existing plastic. I have heated up plastic till it was soft and then lightly “pressed” a pattern into it but I don’t think you’ll match the original. You could sand the whole part smooth then paint but then it wouldn’t match the other plastic on the truck. Harbor freight used to sell a plastic welder kit for around $20. You usually only get a couple of uses before the tip breaks but it comes with some mesh and probably enough filler to do this repair. Disclaimer though. I’m not in automotive refinishing business in any way. I’m a back yard hack and most my experience with plastic repair is non-automotive related. I figure you’re best off leaving as is or replacing. But if those mirrors run the same as my Superduty mirrors that’s a grand or more to replace. And I know that chip would drive me crazy so I understand wanting to do something. Which is why I gave my advice. If it was mine I’d also worry the repair would look worse than the damage. Maybe someone can give you better advice, but I think most are gonna say it needs replaced and that any repair would have high risk of failure/just not look right. If I’m wrong guys please let me know. So if you attempt it good luck.

P.S. I forgot to mention that some plastics epoxy won’t stick to anyways. Things like polyethylene and polypropylene you would have to weld, the epoxy just wouldn’t stick well.
I probably should have checked pricing before I posted. It looks like they’ve really come down. When I checked for mine it was quite a bit higher. If you’d be ok used I just checked on and in my area they have these mirrors listed starting at around 150 and going up to 300. Not sure exactly where you’re located but I’d at least check there. Also, don’t be afraid to call the salvage yard if it’s far away and inquire about shipping. Some of the yards will ship. I know there’s one in Michigan that used to for smaller items such as this. Again I’m not in the business so there may be a better source for used parts…maybe LKQ but I think they’re geared more towards shops, I ordered a bumper from them and had to get it delivered to a local business. That may not be the norm as that’s the only part I’ve bought from them. Again good luck with whatever you decide.
Yes thanks. I’m in Canada. Local used are about $200-$300 a pair. None close by at the moment but that’s probably the way to go since I need a convex mirror also.