Adapting chassis cab flatbed to pickup

[anesthes]

I got this nice aluminum flatbed, it's quite similar to the ones you see at home depot. Theproblem is it's for a chassis cab so the sills are set at 34" apart. It's all gusseted and all that so I don't want to cut it up.

My frame is about 42" apart. Normally I'd just run some rectangle tube over my frame and call it a day, but the bed would be very high. It's high enough as it is, considering the sills are 5" channel, and then the floor crossmembers on top of that are another 3".

I have some 1/2x4" bar stock in the shop. If I lay 3 pieces across my frame, do you all think it would be ridgid enough to hold the body + 3,000lbs of cargo, or do you think it would bend?

Thanks!

-- Joe

 

[flyerdan]

I'd get an OS/OS measurement of the bed rails, and an IS/IS measurement of the frame rails and see what that was. There will probably be enough room that you can run a stick of 1.5" x 3" or so just inside the frame rails, anchored to the four hard points with brackets. With a little plasma trimming it shouldn't be any higher than the rails, and the bed should anchor to it from the inside. You'll probably have to set it in place to get the mounting hole locations, then weld threaded inserts in to bolt to.
If there were any holes in the frame that the additional rails could bolt to, I'd do that as well so there would be more than four anchors holding the whole thing. It would take quite a bit of fussing to get it to lay in right, but it should be a good looking, secure install.

 

[4570Man]

Bar stock has almost no strength like that. I think it would bend.

 

[anesthes]

I'd get an OS/OS measurement of the bed rails, and an IS/IS measurement of the frame rails and see what that was. There will probably be enough room that you can run a stick of 1.5" x 3" or so just inside the frame rails, anchored to the four hard points with brackets. With a little plasma trimming it shouldn't be any higher than the rails, and the bed should anchor to it from the inside. You'll probably have to set it in place to get the mounting hole locations, then weld threaded inserts in to bolt to.
If there were any holes in the frame that the additional rails could bolt to, I'd do that as well so there would be more than four anchors holding the whole thing. It would take quite a bit of fussing to get it to lay in right, but it should be a good looking, secure install.

Are you thinking 90ｰ brackets with gussets?

I could probably cut up all that bar stock into brackets with the plasma cutter.

 

[flyerdan]

I wouldn't use that 1" bar stock at all. Measure as indicated, if the difference is, say 3" then a stick of 1.5"x3" .120" wall for makeup rails and no more than .250" for the bracketing, probably a chunk of 4" wide flat bar would be perfect. You can gusset the front anchors as they are raised a bit, but the back will be straight across.
It looks like there is some plumbing to the back, at least on the starboard side that will interfere with the extra rail, I'd relieve that section of the added rail with the plaz, like I said it will take a lot of fussing to get everything to lay in properly.

 

[anesthes]

I wouldn't use that 1" bar stock at all. Measure as indicated, if the difference is, say 3" then a stick of 1.5"x3" .120" wall for makeup rails and no more than .250" for the bracketing, probably a chunk of 4" wide flat bar would be perfect. You can gusset the front anchors as they are raised a bit, but the back will be straight across.
It looks like there is some plumbing to the back, at least on the starboard side that will interfere with the extra rail, I'd relieve that section of the added rail with the plaz, like I said it will take a lot of fussing to get everything to lay in properly.

I'm struggling to understand what you're saying.

Are you basically suggesting running the one and a half by three sistered to the sills of the flatbed, effectively making it wider?

 

[Mat4644]

You only need 4 inches inside truck frame to contact bed frame. Make supports similar to factory supports inside frame to support bed beam. Modifying front supports would be a breeze.

 

[Oldpath05]

34"-42" frame, interesting problem, if it was me I think I would grab my saws-all with several metal blades and cut the sills off and relocate to 42" and reweld, then see what the cost of a dump kit would be.

 

[anesthes]

34"-42" frame, interesting problem, if it was me I think I would grab my saws-all with several metal blades and cut the sills off and relocate to 42" and reweld, then see what the cost of a dump kit would be.

I actually just took a dump body off of it. It was always way overweight, so I made a dump trailer instead.

I still have a hoist and everything and this body technically is rated to be used as a dump, but I don't want to bend it being aluminum and bang it all up.

 

[BlueKnife]

I have some 1/2x4" bar stock in the shop. If I lay 3 pieces across my frame, do you all think it would be ridgid enough to hold the body + 3,000lbs of cargo, or do you think it would bend?

Thanks!

-- Joe

I think if you used that and then welded some 2" or so bar stock vertically underneath it between the frame rails of the truck it'd work fine. The vertical pieces wouldn't need to be 1/2" thick (neither do the flat pieces either, but you said you already have them....)