I recently glassed the rusted holes beneath my trunk carpet. I plan to use body filler to smooth everything out and make it look good. My question is what is the best filler to use with fiberglass? Also, I have a mustang scoop I may put on my decklid, but I've heard it might mess with the paint if you mold it on instead of bolting it on, true? Any advice is appreciated. Thanks

You may have seen my rantings in many other threads, but I did a simple project- fill in my luggage rack holes- and it turned into a real mess. I used "the correct" filler, SMC, and when I took it to get painted, it bubbled up. Then he excavated all the filler out and put his own stuff in. It bubbled up. Thank God hes an honest man, because he knocked of a substantial amount of money. Long story short- just keep it stock.

I just removed MOST of my stock trunk rack/spoiler but left the "spoiler" and about 4 inches of the rack strips that are attached to the spoiler sides and center. (You have to leave a few inches of the rack to support the spoiler.) THE OPEN HOLES can be plugged with a 1/2 inch white plastic plug available in the small-parts-drawers at hardware stores and Home Depot. They snap right in and look like "rivets". My car is white and they are almost invisable!

------------------
WAYNES' WHEELS: White 84 SE from eBay with 17K.
A touch of blue: body trim, wheel highlights and front pegasus decal.
"Sweet little Peggy, You'll know her if you see her"

I am not a bodywork guy, nor have I done much - but what I have used sofar is just the classic Bondo Body Filler. seems to like fiberglass. used it when I did my hood vent. last year, I rear-end someone, and it wrecked the hood quite a bit. The 3 year old Bondo job did not crack, chip or de-laminate.

If you've already glassed it, and just want filler over that, I think one of the best is supposed to be Evercoat Rage Gold. Hunt around the net and you'll find that is what most high-end bodyshops use. I just bought some to use on my projects and it is very nice stuff.

Rick

The Bondo type filler will work on fiberglass. Although, I personally do not use the Bondo brand. It has wax in it, which gums up your sandpaper. I prefer the PPG brand, which doesn't have wax, and therefore doesn't gum up your sandpaper as much.

That said, your floor is going to be covered with padding and carpet. So smoothing it out with body filler is unnecessary.

Id leave it alone and cover it with drying rubberized undercoating myself, then lay the pad and carpet.

Plain old body filler will work fine on fiberglass. I use cheapo Bondo brand on used cars just because its cheap. I dont have any problems with sanding it. Fiberglass manufacturers (parts, boats, RVs) all use regular filler in their own stuff.

On your scoop, you have to remove ALL the paint where you bond it or it wont stick so reaction to paint is moot. Personally, I finish the edges of scoops and bolt them on. Factories do it. If you really want to finish that off better, go around the base of it with black rubber door edge molding. It looks like a factory gasket. My Coronet 6 Pack scoop is just bolted on the hood.

I used a evercoat fiberglass filler that I got for REALLY cheap. It worked well although it did shrink mildly.

Be sure to let the glass cure for many weeks before sanding or laying bondo over if possible. Sand it from there so it is mostly flat, use any light/fiberglass bondo to fill in the scratches, and sand from there.

The hardener used in most bondo's absolutely requires to be mixed well before you mix with the bondo, as the bleach/peroxides used in it separate from the rest of the goo, which will react with the paint you spray on. Also hardener that is not perfectly mixed with bondo will cause paint to lift.