Fiberglass help on hood scoop

[Bison]

I have already fiberglassed my Capri hood scoop once to fix little cracks. It lasted a couple months until the cracks started to reappear. Is there something more I can put in with the resin to help hold it a little stronger? I'm thinking some of that wire mesh type stuff, but don't really know what it will do. Here are some pictures of the problem areas. Thanks in advance.

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[dagenham]

You need to grind out the cracks and refill them with fiberglass resin filler. That still may not last for more than a few years. The problem is the fiberglass is thin, old and getting brittle.

[gregpro50]

I build fiberglass boats and for that I'd use an epoxy resin. West System sells a small repair kit that would do that. Instructional video for application: https://www.youtube.com/watch?v=eggAzL9oQxg

[wraithracing]

As stated you will need to cut the cracks to get enough space to allow good material to get into the crack area and bridge across it to make the repair. I would recommend reinforcing the back side of the crack with new fiberglass cloth. Matt cloth will work fine, although woven cloth is stronger. The woven cloth can be more difficult to wet out in these types of situation. You can layer up the reinforcement on the backside to give the repair more strength and lengthen the repair area to help with strength.

Keep in mind you can use filler to finish the repair on the top surface, but filler has not structural strength and will only crack again if you don't fix the repair with good glass work. Best of luck!

[86McLarenCapri]

That's all good advice! The West system is a great product--easy to use and excellent quality. I am making fiberglass repairs to rudders on my sailboat and that stuff has been amazing.

On your scoop, you need to grind out about an inch on each side and grind the crack to a 'V'. If you use a roto-zip tool with a small stone bit, you can get a very small valley where the crack is. Then, clean the surface with Acetone and brush on the West System. put your fiberglass patch across the whole ground off area and work it into the crack valley. Brush more resin on top to saturate your patch. Let it cure over night. When cured, sand with rough grit (60-80) and then repeat with another layer of resin/glass/resin. I would use the woven glass sheets for this, but you could use the mat for reinforcement.

You can get sexy with the last layer of glass by covering the area with clear packing tape. It would come out smooth and would save you some filling/shaping time. You would finish off with a filler or glazing compound.

While you are at it, you should consider reinforcing the whole scoop. Clean out the underside with acetone, then sand with 60-80 grit. brush on the West system and then lay your mat on top of it. It would be a good idea to get one of those rollers with knobs on it so that you can roll the mat and get all the bubbles out. You have about a half hour to work with the resin but you can adjust that time by altering the amount of hardener you use. You really only need one layer of glass. Sand it with a higher grit, like 120 when you are done jut to clean it up. You should then have a bullet proof scoop!

[Bison]

Thanks all, I'll try my hand at it sometime soon and see how it holds.