I am wondering if anyone can give me some advice as how to repair this crack?

I bought these wings recently knowing some work would be needed. I am planning to rub down the wings then prime and paint but the crack in the photos needs addressing first.

The grinding of the top surface was done by the previous owner as I haven't touched them yet. The crack doesn't appear to have gone right through the fibreglass. I've taken a couple of pictures of the underneath and the material there looks fine.

I've done search of previous posts but there doesn't seem to be much info about. Chris Gibbs posted years ago with a link to his home website with a guide to fibreglass repair but his home website no longer seems to be going.

All help and advice gratefully received

If you are worried about the structure of it...

I would grind back the FG around the crack and then lay a strip of woven fibreglass tape and resin ontop..followed by some surface tissue...followed by some body filler and a sanding block...

Or just fill it...sand it... and then re-inforce the back side where no one will see it!

Mmm looks like a gel coat crack that's already been filled and sanded.

I'd drill a hole at each end of the crack first to stop it spreading anymore. Then grind bac abit more along the crack and lay up a short piece of matting over it. Then fill with fibre paste and skim with filler then paint.

^^^

As above - someone has attempted a poor repair in the past I'd say.

You need to carefully grind back until the mat just starts to show. Feather out the edges to about 40mm away from the crack. As Omega says you could drill a small hole at the end of the crack to stop it moving. Then use mat and resin over the crack itself a couple of times about 20mm each side. You'd probably just get away with that and a skim of filler depending on depth.

JC

Thanks lads,

What's he best kit to grind it back with? I was thinking a flap disc on a grinder or is this a bit brutal? I've got a dremel type tool also if that is any better.

Also what size drill bit would you recommend or does it not really matter?

cheers

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Also what size drill bit would you recommend or does it not really matter?

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I'd drill a hole at either end and use a cut-off disc in a dremel to enlarge the crack into a groove. Then flood the area with flowcoat, rub it back. Job done. The crack's not that big and the rear wheel arch is well supported and non-structural. I wouldn't worry re re-inforcing. If I was I'd put some matt on the inside of the wheel arch and slap on some polyster resin. I'd use a countersinking drill bit from both sides so they meet in the middle. Nice and gradual, no risk of snagging / tearing.

I had a petrol tank cover on my Rickman Kawasaki years back and after I got it resprayed at considerable expense, all the cracks I had filled reappeared and ruined the paint job.

If I was fixing this wing Id grind the crack right out, all the way through to the other side and make the crack into a slot with the grinding wheel. Open it up just the thickness of the wheel. Feather the edges out as much as you like (you've made a good start) then, as another poster suggested, some chopped strand mat and resin to fill the ground out portion and then some tissue over the top, all in one lamination. You've got a surface to work from so as long as you don't make a big lumpy mess, you'll have a nice strong mechanical repair and a bit of filling and sanding to do. This method will ensure that the crack does not work its way back through the repair, as happened to me. If you use masking tape over the ground out crack in the back you can rip that off when the resin is cured and maybe put a layer of tissue down on that just to finish it off. Cracks in laminates can be an absolute bugger but if you're aggressive enough, you can repair even a big crack. The important part is to remove any delamination or torn edges.

[Edited on 2/3/09 by Benonymous]

Thanks for all the help, I think I will have an exploratory poke with the dremel at the weekend and see how bad it is.

They are 13 inch wide rear wings which I need as I'm using a Capri axle and a pair of fat rear tyres. They are worth spending a bit of time fixing as I dont know where I'll get another set from.

when you do glass them up it'd be an idea to do it in a"fitted state" as I think the crack probably came from the stress put on it by bolting it to a bent or off the square panel this could have pulled the wing down and caused the crack to appear over time.