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Old 10-17-2012, 11:25 PM   #1
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Angry Cracks in the fibreglass exterior

I have a Forest River Shamrock 23RS which has a rear queen bed slide out. I have 2 cracks in the fibreglass which are both located near a corner next to the slide out. One is at the top right corner and the other is at the lower left corner next to the slide out. Both are about 5 inches in length. I also noticed hairline cracks beginning to form in a few areas. My trailer was manufactured in 2008 (sold as a 2009 model) and I am the second owner so there is likely no warranty left. I am wondering if I can repair these cracks myself or is this something requiring a professional. Any advice on how to do repairs would be much appreciated. Thanks!
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Old 10-18-2012, 07:22 PM   #2
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Old 10-18-2012, 08:15 PM   #3
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If the cracks are on the corners of the rear wall at the slide opening, the slide stop may be not properly adjusted causing some flexing of the rear wall. I had a couch slide TT that bowed out the wall before I adjusted the stop.

Try having someone operate the slide and see if the back wall to pushing out around the opening before the clutch disengages. If so, the stop needs adjusting.

Once that's sorted out, the fiberglas can be repaired if minor. A shop that specializes in marine repairs would be a good choice.


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Old 10-19-2012, 12:22 PM   #4
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Cracks in the fibreglass exterior

Thanks Dave for the advice. I am still wondering if I can do this repair myself or if I should take it to a shop. I much prefer to do my own repairs if this is not beyond my skill level (I mostly repair my own stuff - minor auto repairs, appliances etc.).
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Old 10-19-2012, 02:34 PM   #5
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Yep, what dave said!
I have done a lot of glass and smc work on vettes, bedcovers and toppers. The best repair is if you can get to the backside and grind the back broken strands, sand the area to accept the repair matierial with 80 grit sand paper, blow off dust and apply backing patch. You can use fiberglass mat or cloth with resin or what we use most of the time- fiber reinforced tape(like drywall mesh) and 3M's fiberglass and smc repair material, that comes in a 2 part mix tube with nozzles and requires a special gun to use it.

The next part will work after reinforcing the backside or if back is not accessible.
- grind the cracked area out in a V gradually working out from initial crack and grinding out as much of the broken area as you can( if hollow on backside and not accessible leave a thin layer of the broken matt to hold the new material from sinking in to far). And when I say V, I mean feather it out from the center of crack an inch ir so. If you don't feather it out it will not bond to a large enough area to hold and flex with original panels and will crack out again and again.
- After grinding, sand around the area getting repaired with 80 grit at least as far as material is going to be applied.
-now you can fill in with long strand filler, fiberglass matt or cloth w/ resin cutting small pieces and building up with bigger and bigger pieces as you work out.(matt and resin is hard to do on anything but horizontal areas) or like I usually use any more, a little piece of fiber reinforced tape and 3m smc and fiberglass repair material.
- when any of the above has hardened you can grind or sand down. And any further build up can be done with the same or short strand filler or regular body filler, and any pin holes can be filled with glaze.
-final sanding should be done with 150-220 grit and then can be primed. Sanded with 320 grit and then sealed and refinished.
--- I recomend a resperator, latex gloves and long sleaves any time you are grinding and sanding- and of course safety glasses or face shield.

Sounds complicated but someone with a little experiance could knock it out in an afternoon- less primer drying and refinishing.

Hope it helps any ? Just ask!!
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Old 10-25-2012, 11:07 PM   #6
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Cracks in fibreglass exterior

Thanks for the advice with all its details MillerTime. I will have to take on the challenge next spring as the weather where I live (Winnipeg, Canada) will not allow me to do any outdoor work on the trailer before then. I will likely contact the RV dealer where the trailer was sold and see if they will do the work for an affordable price, or possibly a marine dealer. I don't think I have the skills to pull apart the interior of my trailer to do the work on the inside. I am pretty sure the slide out is causing the problems. I need to try and figure out why before I get it repaired. Thanks again.

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