95 F350 dually fenders repair/respray

[EDP]

Hey all, same f350 I did the roof on, the dually “fender/covers” are thrashed so I want to repaint them. I’m not sure what they’re made of, fiberglass ?? Anyone sure what there made of ?

I’ve read quite a few threads on here re:Corvette repaints, seemed one of the cautions was sand down material , spray w/multiple coats of epoxy and let sit in sun to gas off/shrink back (if remembering right ) before applying filler, sealer and final coats.
Suggestions on procedures for these thing are appreciated .

Thx!

 

[RenewAP]

I believe it IS fiberglass, A magnet will tell you. If fiberglass, unless it is broke or cracked, you can just sand it down to the original primer and re-prime (2K) If you sand down to the gel coat or need to repair the fiberglass, then poly primer will be the most compatible to the original gel coat. I may be wrong, but I don't see any advantage to the epoxy on fiberglass, as corrosion is not an issue, and the adhesion of the Poly will be excellent.
I have found that unless you are wanting to get it "show car" flat and straight, that the extra layers of product just make it rock chip and crack easier.

 

[bmenard]

I’m gonna disagree and say sand ‘‘em and epoxy only, 2 coats under filler and whatever it takes on top. Best and simplest way. Epoxy has worked miracles for me on fiberglass and plastic.

 

[Chris_Hamilton]

It's actually SMC (sheet molded compound) which is similar to fiberglass but uses a different resin. If you need to repair it use only material that irated for SMC.
Sorry to disagree with Renew's advice but epoxy is the best thing you can use on fiberglass or SMC. Better even than gelcoat. It has been covered here in many different threads,

 

[RenewAP]

It's actually SMC (sheet molded compound) which is similar to fiberglass but uses a different resin. If you need to repair it use only material that irated for SMC.
Sorry to disagree with Renew's advice but epoxy is the best thing you can use on fiberglass or SMC. Better even than gelcoat. It has been covered here in many different threads,

I'll have to try the epoxy on the next boat I do. I would always spray it on SMC as the adhesion advantage is clear. I still would avoid extra product layers if there's no advantage, but the epoxy is a rather amazing product, so I will have to try it.

As a extreme test, I sanded down some very bad rust scabs with 80 grit on my DA on the front edge of the hood on my old Caravan delivery van. 320K + miles. These scabs were 4-6" around, and had a few holes rusted all the way through the metal. I simply sanded them flat, leaving most of the rust. I sprayed 3 coats of white epoxy on just the sanded areas (PW7 white hood) . This was more then a year and a half ago in Wisconsin weather and winter salt. It still is holding strong. As a SPI distributer I use this as a customer show and tell for the epoxy.

 

[MikeK]

Easy to tell if it is.SMC looks like fiberglass but obviously different once you Look at it raw. More like sheet rock, really compacted product. Not fibered at all, well not like 'glass anyway.
The 85 Dually I did had one that was smashed/splintered on the rear of it.
I basically glued it back to form with smc type resin/hardener to work it after a gentle media blast of the original paint. Then smc resin and 'glass mat on the back side for support and metal glaze filler on the outside.
2 good coats of Spi Epoxy and blocked it up to 150gt,2 coats of Feather Fill 2k poly primer to White Spi Epoxy for the finish. Was Spi Red when finished. Yeah,the inside didn't win any beauty contests but that wasn't the idea anyway. I have pics if you want just not right now.

 

[EDP]

Thanks for all the input/ideas. I’ve got 3/4 gal of white epoxy and a qt of black so planned on that anyways. I like using the epoxy as final primer , sands out nice and seems to work great , it’s what I painted the f350 roof with.

My only real “plastic” experience is the air grabber hood bubble on my 71 Satellite, it was cracked to hell and I ground em all out V groove style epoxied it and used West Systems epoxy with some “micro balloon” filler added as thickener ( looks like finely ground up fiberglass) and it worked perfectly on the hood bubble. Had a hard time determining what they’d made those old bubbles out of & was told the WS will not shrink .

No issues with that material , was thinking of using that on these fenders, they do have some decent sized divets in them that need filling . Is Rage gold an SMC compatible product? Got that too...

So if I sand down to base material / original primer then epoxy can I do that immediately or do I need to wait to let plastic to off gas before epoxy? Or is that only an actual fiberglass issue?

Also, are these fenders hard to pull off truck bed??

Thanks all!

 

[EDP]

So I just realized now I'd posted this question last year when I posted it again a hour ago - now deleted !

Its either early onset alzheimer's or the fact I waited 9 months and did a house renovation project inbetween. Getting back to these fenders finally, is my last post of questions on 10/1 accurate?

Will the rage can tell me if its SMC compatible, if not what to use or is the West Systems a good idea?

Thanks all !

 

[EDP]

Can anyone tell from these - fiberglass vs SMC ?
Image on right(pass fender) looks like fiberglass strands , other 2 don’t really (drivers fender)

 

[crashtech]

The stock fender is SMC, a previously repaired area may appear more like fiberglass.

 

[AAE]

Polyvance has an SMC hardset filler that works well.