Quote:
Originally Posted by rvcycleguy
I see what your chatting about. I thought it was on the bottom of the roof, which is the stirrup hold down, but your dealing with the underside of the bottom box. There are rivot nuts that can be installed into the bottom. Like an expandable nut or sleeve that is threaded for a machine nut. Not a lag screw that essentially digs or carves itself into the wood or metal and over time can pull out. As you mention, wood rot is probably the culprit there due to the underside is so close to the road surface and rain, wet roads can penetrate over time. Does appear that there is some staining with a wet area. I don't know I would open up that can of worms on what's under the bottom panel or belly cover. I've offered a link for rivot nuts.
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I tried this solution, rivet nuts rely on going through a structural metal hole and crushing to the opposite side to hold. The bottom of the TM is plywood sheathed in thin sheet aluminum. The wood doesn't resist the expanding rivet well enough to hold and the sheet aluminum is just thick enough to protect the wood from water.
I was hoping that a sheet of steel reinforcement was there that I could see between the wood and the aluminum sheet due to the dark color of the hole.
I am going to try pumping structural epoxy into hole with the bolt and see if that can make a strong enough bond with the wood to resist the tension pull.
If I were to redesign the construction of this part of the TM, I would use blind nuts instead of relying on lag bolts, which I believe are better in shear and less so in tension.
Dave