Tried to weld fenders before and it looked good but they broke when we went riding in 0 degree weather, A buddy showed me how to sandwich the cracked pieces with tin and rivet it together. A little paint if you want then you are on your way. Have not had any problems with the fender since this type of fix.AlaskaBoy.

 

I've used the "glorified soldering iron" one quite a bit and it's works very well, but takes a little practice. The polyethyene rod works the best on ANY fender I've ever welded (I've used old cut up fenders too, but the rod works a little better I think). The main trick is to get the plastic to the right temp, not hot enough and it won't melt together, too hot and it turns to goo. I use a die grinder to V out both sides of the crack, tack it on one side and lay a good bead on the other, go a few inches and allow it to cool enough to have a bit of strength, then go on. Then I weld the back side. The part I've welded ends up being a bit thicker than the rest of the finder. To make it look good, I take my die grinder and thin it out, try to make it match the rest of the fender. You can tell it's been welded of course, but IMO very acceptable. I've also found that the welds can be made stronger than the rest of the plastic if you leave it a bit thicker and get it melted together properly. The downside...very time consuming, especially if you're paying shop time. BTW, I think that welder is pretty reasonable to buy, when we bought our first one about 15 years ago or so, i think it was under 100 bucks, we replaced it a few years ago and seems to me it didn't go up in price THAT much.

 

I welded up a fender just this week, trying some of the suggestions posted here, and the method of "mixing" the hot plastic together seemed to produce the strongest "weld", although it was the ugliest too. Another method I tried that worked pretty good was to heat up both sides until they started "sagging" and then pressed the plastic from the top and bottom "fusing" the plastic together until it hardened.

I have tried the liquid type plastic repairs before, and from my experience, the repair has always been more ridgid than the fender plastic, resulting in breaking the "welded" area - more like it was designed for ridgid plastic like ABS. Kind of like the post from ajo771, the article says the fender plastic requires drilling holes for their stuff to bond to because the solvent doesn't melt the fender plastic.

I was looking more for what dzzy has posted, wanting to make the weld more like welding metal - I will try this the next time I have to weld a fender and see what the results are.

Thanks again for all the replies.

 

I agree. I posted that article just so people know what thier options are. The "FUSION" method I spoke of early on in this post is true plastic welding and is by far the best method Ive ever used. Just takes a little practice (like real welding) and you get a stongest repair.