Flat bed to chasis mounting

toyota1

toyota1

Well-Known Member
Joined
Apr 17, 2008
Location
Fort Mill, SC
Looking for some input on building a flat bed for c&c 1999 f550 that will be my crawler hauler and pretty much anything i want to move. Im just curious what everyone thinks is the best way to mount the bed to the frame. I wouldnt be concerned as much but im putting a gooseneck hitch on it and it will be part of the bed.
Picture is the wooden first step of design
 

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@mcutler built a nice bed for his ford. He can probably give some good advice.
 
I dont think @mcutler put a gooseneck in his. If it wasnt for the gooseneck it would be easy
 
What brand is that? I'm trying to find it on their website.
 
@Croatan_Kid its part number 1500 from b&w they dont make a chasis mounted gooseneck plate for my truck so i went this route
 
Why not do a trap door design for the gooseneck ball instead of spending the money on a pop up ball? Open door to reveal ball or close it for flat bed.
When I mounted my flat bed to my c&c I put some treated 2x4's between the frame of the truck and frame of the bed. I have no idea if this is good or bad, just did it b/c I have seen it on other trucks and larger box trucks.
 
Jman78CJ7 said:
Why not do a trap door design for the gooseneck ball instead of spending the money on a pop up ball? Open door to reveal ball or close it for flat bed.
When I mounted my flat bed to my c&c I put some treated 2x4's between the frame of the truck and frame of the bed. I have no idea if this is good or bad, just did it b/c I have seen it on other trucks and larger box trucks.
Click to expand...

The wood between the bed and frame was standard from Ford in the 60's. Even my 79 dump truck has wood between the bed and frame. Easy to cut out and a soft landing. Have no idea if the 79 was stock for it is treated? The 60's were definitely not and rot became an issue.
My '64 Flatbed has 3x6's stock. I'm in process of mounting it solid with metal though.
 
Link to my bed build.

Work truck build

I added nothing between the flat bed and the ford frame. Rear of bed at hitch is bolted to the sides of the frame. Front of the bed has some massive square u bolts from a dt466 or something. it is then tightened down to frame and bolted through the sides as well. I left provisions to add a goose neck of I later desire, (which I hope I won't, i don't like goose neck ride empty or loaded). Only have to cut a trap door and add a ball. Plate is already in the frame. Let me know if you have any questions or need one built. ...
 
I ended up buying the ford manual for aftermarket beds and it says to use sheer plates from the bed to the chasis so thats what i did.
@Jman78CJ7 i went with that hitch because i will ocasionally be pulling a 5th wheel trailer also and its a b&w
 
Sheer plates? I have built numerous beds and plenty with gooseneck hitches. I have also used various mounting techniques and hitch designs, but that term doesn't register. Please explain.
 
Basically just a plates at all 4 cornes welded to the bed rail then bolted to chasis in spots with holes that are already drilled for that purpose. I looked at new dodge at the dealership and thats how it was done as well. Itll be 5 grade 8 5/8" bolts per side
 
Oh, fancy wording for known technique. In the old wood and ubolt method, most of this was done to over come the fact that older chassis designs allowed for alot of flex. The wood was basically an old school flexible bushing. Not that the wood compresses much but it allows it to slide and move a bit. Sort of a rigid structure floating on the frame. Newer double rails, box designs and better alloys are much stiffer. The result is less chassis flex and the suspension working more. Still in many long applications some thought should be taken for less rigid mounting. Many fire apparatus use an array of bushings, supporting out rigger frame designs, and even spring loaded floating bolt designs. Basic flatbed mounts in almost all production beds use the bolt on bracket methods. The best one bolt front rear and mid ship for gooseneck. Several aluminum builders build a generic frame work that includes the front, gooseneck hitch, and rear mt. substructure. It is even multi patern drilled for several models. Then the aluminum flatbed is bolted to the subframe.
 
Yeah sheer plate is just the term used in the ford manual
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heres that plates i made for the front and rear and im going to put 2 u bolts just in front of the gooseneck. The plates are mouted with 10 5/8s bolts
 
U bolts apply more of a clamping pressure straight up and down. They don't fight the forward and rear pushing forces exerted during towing. Hard breaking is the worst. Many manufactures like B and W produce hitches using one or so similar u bolts on the frame area but they also use several through bolts in just the hitch configuration. I would suggest applying a minimum of 2 bolts per rail on the hitch area. A lot of people use 3 by 4 3/8 wall angle, 1/2 by 4 flat bar or similar in this area to spread out the hitch load and bolt through it. Often I see them bolted and welded (though in these cases the welds are questionable any way). And as always be sure the hitch area is "beded" to the frame. Floating rails or center areas are suspect to twisting from the forces. Look at the hitches on line and you can get a good idea of how they spread the bolt patterns out in the middle of the factory rails.
 
On another note to the purist of frame "engineers" tacking, welding, and drilling any of the flat areas of the rails especially in front of the axle is highly frowned upon. I doubt the size of those tacks are going to due to much to the integrity but the purist will argue the internal and external damage to metal grain structure will degrade the rails. But this is coming from a guy who clipped and shortened the CA on one truck three feet and added the same amount to another. Both of which are actively being used in fire service. :D
 
Haha i knew my tacks would be pointed out as bad. I used existing holes for the 5/8bolts in the frame so no drilling but those tacks are all very small and cold i just needed to hold the rails to the frame while i built the bed.
The front plates are over 16" long front to back to spread the braking load and rear is 9" long 3/8 plate all the way around.
 
hey no more fancy words we are keeping this thread "real". glad we're not concerned with single or double "shear" those panti hose get expensive
 
I just noticed that but my phone auto corrects to sheer.
 
I used to design aerial lift trucks (some on F550 chassis) and we used shear plates. You did it right. They also had no issues with drilling holes in the vertical part of the chassis frame in front of the axle to mount the shear plates.
 
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