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View Full Version : Repairing fiberglass?


V
06-23-2013, 03:28 PM
I have a fiberglass part that has 2 significant cracks on main areas. It is structural, not just cosmetic. However, replacement is impossible, so repairing is the only option.

I'm trying to research the proper way to do the repair. So far I've learned that I need to grind/cut down into the cracks and clean them out, basically V them out. Once that is done, I'd use fiberglass resin and fiberglass mat(not cloth) and start laying pieces in and soaking them with resin. I will try to gain access to the back side to lay additional fiberglass matting. The part is not thin like a hood and should not have much, if any, flex to it.

Questions:
1. Once I have the areas fiberglassed, do I just use bondo the do the final smoothing? or a special product for going on fiberglass?

2. All the paint needs to be removed from the part. I will carefully scrape/sand it off. So the whole issue of gelcoat comes use. From checking the corvette forums regarding fiberglass prep, it seems gelcoat was only used by the factory with the lacquer paint and not on the late 60's and up cars. So I shouldn't have to worry about doing a gelcoat. The overall opinion is that a quality high build epoxy primer sprayed right over exposed glass is the route to take and will seal and cover any fibers. Is that correct?

3. Once its actually ready to be sprayed with primer and paint, do I need to add a flex agent to the primer and also to the paint? Although it shouldn't flex due to thickness and weight, I'd rather be safe than sorry.

grazi
06-23-2013, 04:40 PM
I'm no auto body pro but have a decent amount of repairs on kayaks and hoods including the one I brought from you. I always grinder a v out of the crack, then used mat or cloth to span the crack. Then poured alittle extra resin over the last piece of cloth. That makes it so you won't sand down to the cloth. Then I used a bondo over everything, then a glazing putty over the pinholes, if any. Then hit it with a couple coats of high build primer and sand that. Then your ready for paint. Hope that helps.

1320B4U
06-23-2013, 05:38 PM
Correct on 'v'ing' the area out. This stuff is real good for build up and reinforcement too.

http://www.clausenautobody.com/proddetail.php?prod=gorilla-hair

Sometimes, depending on the part, you can reinforce the backside w/a metal structure to provide better rigidity.

V
06-23-2013, 07:01 PM
yea, I found a few fiberglass based fillers so I have to research which is recommended. Access to the back is limited at best, but I'm going to try. I dont want to hack it up too much considering there are less than 750 of these worldwide... lol