Eyebolts and backing plate question

[traveller]

just sold my Tacoma and bought a F250. I now need to mount my FWC and drill some holes in the aluminum bed. Which brings me to the following question. Most are adding large 1/4 inch aluminum backing plates under the bed. I plan on doing that as well. I was also planning on adding a plate, maybe 2x6 by 1/4 inch on top of the bed. Figure this would also help distribute the load better and help the bed from bending etc. I haven't seen anyone else do that. Is there a reason NOT to do it? To me it seems like additional insurance to protect the bed. I would also have a thin strip under the backing plate where the bed indents.
Thoughts?

 

[kmcintyre]

I did that (but not on a Ford but a RAM) just for insurance. I also did the same in my FWC where the eye bolts are and upgraded all the hardware, etc.

 

[steve whiteside]

I cant think of any harm in doing that. Basically you are sandwiching the bed material with load dispersing plates. I don't see much use for the upper plate but I don't see a drawback either. As a related note. Last fall I bought my new Grandby and had the factory put in the mounting hardware. My last trip back from baja showed one of the turnbuckles gone and the truck bed where the eyebolt penetrates the bed is deformed into a 1/2 inch high dimple around the eyebolt. I think the camper tried to jump out of the bed, deformed the sheet metal of the bed. That deformation provided some slack in the turnbuckle which fell off and rattled out the back of the truck.

Steve

 

[Beach]

Sounds like a good plan. I would also encourage you to radius all the square corners and edges of the plates to prevent a can opener effect if/when they are pulled off angle. Prime any holes you drill before installing plates.

 

[Jon R]

I put a 1/16 thick piece of polyethylene sheet between my 4x6x1/4 aluminum backing plates and the bed metal in addition to breaking edges and rounding corners. I wanted to avoid rubbing through my bed’s corrosion protection.

The upper plate helps spread out the loads from the shoulder of the eyebolt that arise from lateral load. How much difference it makes depends on the angle and tension on the turnbuckles. I used a 1.5x2x1/8 inch top plate that fit nicely in the bed groove where the eyebolt is. This is a big improvement over no plate, where the edge of the eyebolt shoulder is pressing only about 1/8 inch from the hole. With less than a 30 degree turnbuckle angle from vertical, a large bottom plate and a small top plate should be fine as long as the eyebolt is tight, maintaining the clamping force.

Just remember that anything you do that increases the height of the eye above the bed increases the cantilever length and increases the bending forces for a given lateral load, so minimize your stackup if you add a top plate.

 

[traveller]

Jon R, good advice on the polyethylene sheet between the bed and the backing plate. Maybe I'll find a piece of hard rubber material to put between both surfaces.