Motorcycle fender finishing

Anything goes in the world of fiberglass and plastic



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PostPosted: Tue Oct 22, 2019 9:28 am
I'm not a body guy, just cheap and competent. I have a fiberglass motorcycle fender that my prepping (SEM high build aerosol) has shown needs something thicker than primer to fill a slight depression left by the molding process/fabric seam(unless I do quite a few heavy primer coats but I'm pretty sure that's not best practice). The fender needs to be compressed to fit through the forks and even though it's just a small/thin area im hesitant to use Bondo as a glaze for fear that it would crack. This isn't a show bike, just my commuter so Im looking for something cheap and readily available locally.

All help appreciated,
TroyC

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PostPosted: Tue Oct 22, 2019 1:03 pm
Hmmmm.... so you want it probably thin but still flexible.....I would think USC's Poly-Flex might work. It can withstand something like 100 degrees of bend on plastic bumpers. I've use it and it's less flexible companion, Body Icing with great success.
Here it is on Amazon...
.https://www.amazon.com/U-S-Chemical-Pla ... B0082LFHNY
Shop around for the best pricing.
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PostPosted: Tue Oct 22, 2019 3:33 pm
Lol I actually thought the same thing, ordered the single use flexible glaze and got a call today from pep boys and they now can't get it/not available and cancelled my order, called the company directly and they said they dont distribute to Florida...I can do Amazon but it's a week delivery for 2x the price and I'm looking to spray tomorrow which is why I came here for help.

Other than finding a local shop that uses that product and offering 10$ for a quarter size glob w catalyst...any other ideas?

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PostPosted: Tue Oct 22, 2019 11:38 pm
Any of those flexible fillers are not cheap....try some local paint jobbers (PPG, Transtar, Dupont, etc.) and see if they've got some of those smaller dual syringe kits or the smaller tubes. Just make sure whatever you get it rated for flex and is a catalyst hardened filler.
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PostPosted: Fri Oct 25, 2019 8:15 pm
Ok, new fun. So I ended up using SEM bumper repair a flexible 2part epoxy that reminded me of JB weld from both color and odor. It went on and sanded well but kicked fast.
Anyway, new problem. I primed and let sit till today when I went to grab for a final sand I noticed a dark .5" "stain" and a few smaller less dark ones and even a light white color blemish NOT associated with the repair area. I know now that I was prepping incorrectly, used 91 IPA applied to a lint free rag. Could this be from that? Should I be concerned with bleeding to my base?

Forgot to add that all the plastics for this bike were prepped the same way Including using the same epoxy repair on a few spots and do not show any flaws in the primer. All were cleaned with Dawn and a scotch Brite and dried indoors for 5 days, then a IPH wipedown , plastics got a spray of SEM plastic prep then 2 coats SEM high build, sanded with 400g, cleaned as per above/IPH, 2 more coats SEM.

...also this is a fender from a top quality manufacturer, it's been on the bike for years so oil etc. could play into it.

Again, all help appreciated
TroyC

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PostPosted: Sat Oct 26, 2019 8:32 am
So the 91 IPA is isopropyl alcohol? Were you using that straight? Hmmmm.....wonder if this part was an open molded part or possibly an SMC (sheet molded compound) fiberglass? SMC has more porosity to it and stuff can indeed "bleed" up..... I mean even regular fiberglass can trap stuff if it gets driven down past the gel coat......not sure what to tell you on this......
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