Grandby flatbed with behind-the-cab boxes?

[Bluebeard]

Hi all -

I have an F-350 crew cab diesel with a 9' flatbed, otherwise stock, and have a Grandby flatbed on order, with delivery in April 2021 (!).

A lot of forum folks discuss the limited storage space, and to address this (we will be travelling with 2 young boys, so lots of stuff) I was hoping to put a "backpack box" behind the cab, and consequently would have to shift the camper back to accommodate the width of the box. Most of the commercial backpack boxes are 2' in width, and the Grandby has a 7'9" footprint, so this would have the back end of the camper hang off the back of the 9' flatbed by about 9".

I've seen photos of similar setups, and in fact FWC has photos of similar setups on their Grandby web page. However, when I ran it by the FWC installation guys, they were concerned about the center of gravity (COG) of the camper sitting behind the rear axle, potentially destabilizing the truck off-road and hindering braking performance. While I understand this concern, the camper is pretty light compared to the overall truck, and with a crew cab/front engine truck the COG is already so forward biased that I can't imagine the overall COG of the truck:camper union being anywhere but between the axles where it belongs.

Just curious to know if anyone has this kind of a setup, or if there are any owners with this setup who are willing to comment on any performance issues. Also curious whether airbags might help level the load and better distribute it between the axles.

Thanks in advance for any input

 

[longhorn1]

I would listen to FWC. Just get a small offroad trailer to haul all your supplies.

 

[heinphoto]

Most of the flatbeds with tunnel boxes I have seen have been with Hawks. Although I know of at least one Grandby with tunnel boxes, but it is on a standard cab truck, I believe. The flatbed floor plans have a lot more internal storage than slide-ins. In addition, you may also have external storage cabinets on your flatbed (or if you already have the flatbed, maybe you can add under-bed storage cabinets?). So, you may actually not need the tunnel boxes. The Grandby flatbed has a ton of storage under the dinette seats and cabover bed.

 

[Bluebeard]

I do have a pair of small underbody boxes, and will probably add two more, but it's nowhere near what we will need to accomodate skis, boots, helmets, Pack N Play, and all the other crap it takes to keep the kids entertained while we try and drink wine in peace I specifically went with this setup to enable us to drive faster than 55, which we would be limited to while towing....

 

[rando]

Given how much you are investing in this, could you just have someone fab you up a 15" wide aluminium box to keep the camper on the flatbed? It seems like it would not be that expensive and would be more elegant than having the camper hangin off the back.

 

[Durango1]

Hi all -

I have an F-350 crew cab diesel with a 9' flatbed, otherwise stock, and have a Grandby flatbed on order, with delivery in April 2021 (!).

Just curious to know if anyone has this kind of a setup, or if there are any owners with this setup who are willing to comment on any performance issues. Also curious whether airbags might help level the load and better distribute it between the axles.

Thanks in advance for any input

I basically have what you describe, Bluebeard, except we're running a 2018 Ram cab & chassis in a regular cab. We had our tunnel box custom made at 22" wide. (I wouldn't go much narrower because you'll lose functionality.) Almost 30% of our box is taken up with the Ram's full size spare because in a chassis cab it doesn't have room between the frame rails.

Even with the Ram's 4,000# payload we put additional springs on the back since it was sagging a bit. On my previous Ram 2500 with a flatbed hawk we put air bags and they worked. But most here will advise you to bite the bullet and respring. They are correct.

re: weight distribution you'll learn a lot with weighing both the front and they back axles on any good scale.

We also heavily modified the cabinets inside our Grandby to make them much more accessible. Sorry but I'm too dense to understand how to post photos here! Email me at steve.toburen@gmail.com if you want to see how we set things up.

Best wishes,
steve