Cracked the bed of my truck
So, this summer my camper spent a lot of time on the truck. Made several long trips. One to Inavale Horse Trials in Oregon and another to Kalispell, MT for The Event at Rebecca Farms. In September I...
Forum Discussion
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It's dark (and cold) outside now but it did make me curious what the floor/underside of my 2000 F-250 looked like, so I took a flashlight. The design shape is apparently identical to your newer truck, although the trend is to use thinner, higher carbon steel all the time. I don't believe my truck ever carried a TC (yet), but I was more interested in the structure design.
It looks like there may be a transverse crossbeam running right behind the crack area and the smooth rear box edge is probably thicker/reinforced across the top also. This would mean that the cracked area of thinner corrugated floorpan on your truck occurred right on this edge of firm underpinning. Adding to the stress, I would also surmise that there may be slight factory cracking, or at least work hardening, of this same area because of the forming process. I think that the ribs always flex from load, but particularily the rear of the truck bed is under high pressure from the cantilevered camper extension. Note that the ribs are the high plane at the rear, higher than the stronger rear transverse box edge which is at the same height as the rib valley's.
I would agree with those that have suggested diverting the load to the bottom of the bed corrugation with a "spacer the height of the ribs for the valley". In addition, I definately believe that a spacer across the back of the stronger bed edge would also go a long way relieve the rib pressure at the rear.
Really, when we think about it, the ribs are not there so much to bear the bed load on their top peak as there are there to form many valley sidewalls that stiffen the broad expanse of sheet metal. That the load is borne by the top rib surface is just incidental. All this to avoid the oil-canning ripple effect. Or since old type shop oil cans are not so familiar now, to avoid the cricket sounding noise maker effect that snaps bulging metal planes. So the concensus is that we needn't ride the load on the rib tops. It is perhaps even desirable to ride all the the load in the valleys since they are directly supported by "joist" framing underneath and do not flex like the hollow top rib "protrusions".
I know someone else more-or-less said all this already, in less words, and I am saying I agree because of the elaborated logic above.
Wes
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It's dark (and cold) outside now but it did make me curious what the floor/underside of my 2000 F-250 looked like, so I took a flashlight. The design shape is apparently identical to your newer truck, although the trend is to use thinner, higher carbon steel all the time. I don't believe my truck ever carried a TC (yet), but I was more interested in the structure design.
It looks like there may be a transverse crossbeam running right behind the crack area and the smooth rear box edge is probably thicker/reinforced across the top also. This would mean that the cracked area of thinner corrugated floorpan on your truck occurred right on this edge of firm underpinning. Adding to the stress, I would also surmise that there may be slight factory cracking, or at least work hardening, of this same area because of the forming process. I think that the ribs always flex from load, but particularily the rear of the truck bed is under high pressure from the cantilevered camper extension. Note that the ribs are the high plane at the rear, higher than the stronger rear transverse box edge which is at the same height as the rib valley's.
I would agree with those that have suggested diverting the load to the bottom of the bed corrugation with a "spacer the height of the ribs for the valley". In addition, I definately believe that a spacer across the back of the stronger bed edge would also go a long way relieve the rib pressure at the rear.
Really, when we think about it, the ribs are not there so much to bear the bed load on their top peak as there are there to form many valley sidewalls that stiffen the broad expanse of sheet metal. That the load is borne by the top rib surface is just incidental. All this to avoid the oil-canning ripple effect. Or since old type shop oil cans are not so familiar now, to avoid the cricket sounding noise maker effect that snaps bulging metal planes. So the concensus is that we needn't ride the load on the rib tops. It is perhaps even desirable to ride all the the load in the valleys since they are directly supported by "joist" framing underneath and do not flex like the hollow top rib "protrusions".
I know someone else more-or-less said all this already, in less words, and I am saying I agree because of the elaborated logic above.
Wes
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