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  View original topic: fiberglass question
hotair65 Wed Aug 29, 2007 1:24 pm

the top middle of my hood is cupped(warped) probably from sitting for 20 some odd years. if i push on the center of the hood from the bottom it pops out , almost like a large dent on a metal panel. if i heat the hood in my friends bake booth at his shop do you think it will alow me to take out the "dent" and let it cool that way.i am going to re-layer some glass on the back after but i cant seem to get it to hold shape. i have tried wooden ribs and braces to push the hood into position, but they dont work right. they end up distorting the entire hood. any ideas?

Elwood Wed Aug 29, 2007 2:14 pm

I have repaired such things by cutting and repositioning.
Major job but sometimes thats the worse case scenario.
With out pics it's only a guess as to how bad it is.

lostinbaja Wed Aug 29, 2007 2:44 pm

I have fixed 2 "dished" hoods. Do you have a picture of your hood?

hotair65 Wed Aug 29, 2007 2:51 pm


hotair65 Wed Aug 29, 2007 2:52 pm

if you drew a line across the wiper mount holes and triangulate it to the gass cap. that is the dropped part. tough to see on the pic. basicaly the whole area around the hood scoop

seabeebuggy Wed Aug 29, 2007 6:14 pm

2 easy way to fix it.
first. With hood removed. Turn the hood upside down add a little weight on the area to hold the sag out . Take a small round foam tube. Home depot sells it . It is used to fill gaps around doors, premade foam about 1/2 round and 15 foot of it in a box...

Lay the foam across the sag area from one side to the other then lay glass and resin over the foam tube. let it get hard. Take off the weight. now it will not move again. this makes it very strong and adds almost no weight.
Another way to do it is with hood on body . use something to hold dent up from the outside or inside but knowing it will not be removed. Use expanding foam. It is called good stuff from home depot.. The foam will fill the area over the tank. It is very strong but not so easy to remove the hood if you ever wish to.. I would tape plastic over the tank to act like a nonstick. So if you ever do remove the hood the foam will not hold the 2 parts together.

hotair65 Fri Aug 31, 2007 6:50 am

think i am gonna go the fiberglass route. are you talking about a foam weatherstripping?

mach4 Fri Aug 31, 2007 9:58 am

It's kind of hard to visualize exactly what the problem is but there are essentially two routes to fix the problem.

[1] Leave the indentation as is and fill it.

[2] Pop the indentation out and attempt to support it from underneath

The proper route kind of depends on the severity of the problem.

I would probably be inclined to attempt the first solution because that condition is "stable" - it has deformed but it has taken a "set". If it is really deep, I would layup layers of fiberglass of decreasing size following the contours of the depression (think coutour lines on a topo-map). If you do this right you will have "leveled" the area leaving it just a very small amount lower than final contour. This can be filled with a thick slurry of microbaloons and epoxy of about the consistency of Rage (essentially a very strong "bondo"). Then sand to rough finish and hit once more with a good plastic filler like Rage. Prime and paint and you're done.

The second solution would entail "popping" the indentation back to it's original position and somehow holding that in position while you support the rear. What I would attempt here is to epoxy (using a epoxy/microballoon slurry) several 1" x 1/4" foam strips to the bottom about 1" apart. This will give you a series of "ribs". Then layup about 5-6 layers of glass cloth over your ribs. (Paint the ribs with epoxy/microballoon slurry before you do your glass layup to ensure a good bond to the foam) By the way, this will not work with polyester resins as it will dissolve the foam. This should provide plenty of support.

There's actually one other solution you could try for #2 strategy and that would be to cut out a piece of sheet metal an inch or two larger than the popped area. Support the area in its original position as above, only this time glue the sheet metal in place using an epoxy/flox mixture. Slather the mixture on the sheet metal quite heavy (such that as you put pressure on the sheet metal, the flox mixture spreads out providing a 100% contact between the underlying fiberglass and the sheet metal. )

In the second case, it probably won't be exactly level, so you will probably have to finish the surface with a good body filler anyway.

In all cases make sure the fiberblass is ground down and clean to get a good bond. A wire brush in a drill or die grinder works good as do disc sanders e.g. DA sander with something like 80 grit. (Wear a mask, eye protection, gloves and long sleeve shirt as fiberglass dust is ugly) If you go the sheet metal route, make sure you rough up the metal good to ensure a good mechanical bond.

Epoxy and fiberglass materials can be secured through boating supply centers or try aircraft supply places that cater to the homebuilt crowd, like Wicks (www.wicksaircraft.com) or Aircraft Spruce (www.aircraftspruce.com).

Hope this helps.



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