Mounting a flatbed ?'s

[Fordsandguns]

Okay, so my truck had a home built flatbed on it when I got it. It just wasn't finished and they put the fuel fillers up top right in the way.
I bought a used commercial built bed for a good price. It needs a little tlc but it's not bad.
It also has a built in goose neck which should be a plus even though I don't have one.
The unfinished bed is mounted with two pieces of c channel up front and slopes down in the rear where they bolted it straight to the frame.
The bed I bought has the mounting pieces bent where it was set on the ground so they need some work. They also look a little flimsy to me and I want to use thicker stock in their place.
It has five pieces of flat iron in what seems to be odd locations to me.
The front two set kind of far back from the front of the bed and the two rear aren't even with each other. And one odd one somewhere in between.

I haven't ever put one on before so I'd like to know the right way to do this.
Especially with the gn ball on it I would assume it needs to be solidly mounted.
It came off a 90 f250 btw.

 

[MIDNIGHT RIDER]

The mounting brackets on your new-to-you bed are most likely specific to the truck that it came from and will be of no use to you.


The flats on my trucks have channel-iron frame-members running length-wise.

These are the same width as the truck rails = 34-1/2" outside to outside.

If your truck is not a commercial cab-chassis, it's frame will not be standard width.

In that case, some improvising will be in order.

On my cab-chassis trucks, there are thick plates welded onto the flats of the channel-iron that extend down the outsides of the truck frame, where large bolts attach them to the frame; one of these at each corner of the flat, about 1/4" thick and six-inches wide.


Many later-model trucks have "perches" riveted to the outsides of the frame put there for mounting a flat.

Store-bought flats have matching brackets made on them that mate with these perches and just sit atop them and a bolt passes through both.


These are convenient for dealer/installers to quickly attach a flat; BUT, they are in no way nearly as stout as the way mine are attached.


Without actually being there, seeing what you have to work with, it is hard to envision just what remedy you will need.

 

[MIDNIGHT RIDER]

On further thought, your best way out may be to design four L-shaped perches to attach to your truck frame.

Then design mating brackets on the flat to attach to these perches.


THEN, once you get the flat mounted on the truck and bolted onto these perches, you can better see what you need and fabricate some bull-stout mounting brackets that firmly attach the flat to the truck.

The perches can just be left in place for those times when you might have need to remove the flat, making that chore easier.


So long as you aren't pulling anything with the flat, you can use the truck to a fair-the-well with the flat just bolted to the perches.


All this talk about flats has got me in the notion to build another one; each one is better than the last.

 

[Fordsandguns]

MR, by commercial I meant factory made, the truck it came from was a pick up not a cab chassis. So the rails match.
It's just that the mounting brackets are kind of haphazardly placed. You said yours were at each corner, these are nowhere near the corners.
So will four brackets be enough?
The bed is nine feet long and I don't remember the width right now.
Also the bed has no provision for the fuel fillers. Any solutions there?

 

[towcat]

every flatbed I demount, I am fanatical on stripping everything that is remotely related to it. every one I have taken apart has had 4x6 hardwood bedding that has been routered to fit the hump in the frame. flatbar and all-thread make up most of the mounting brackets except for the left front where the fuel tank is in the way.
hit a wrecking yard where you can get "experienced" filler hose and pipe. buying this stuff new is ungodly expensive.

 

[Dieselcrawler]

i used body lift pucks in the original bed mount holes. got 3 inch tall pucks and cut them down so the bed sat level all the way back. never had an issue with them cracking or squashing. granite i never had a load on my bed, but off road i put the frame in some really wicked twists and never had one break.

 

[MIDNIGHT RIDER]

I like my four big brackets and the flat "suspended" above the truck-frame.

I have probably put mine to more serious duty tests than most anyone else will ever have cause to.

My receiver hitches and the goose-neck plate are firmly welded and an integral part of the flat itself.

I occassionally see the contoured-to-fit wooden beams sandwiched between a flat and the flat then sort of squeezed to the truck via the long U-bolts or flat bars and all-thread; and, I have also seen that type of mounting get knocked askew or pulled backwards a foot or so.

The always wet wood against the frame and flat is a source of corrosion.


Also, wood is not a constant; it is always swelling and shrinking, thus always working itself loose, requiring constant surveilance of the mounting straps.

 

[Diesel_brad]

Okay, so my truck had a home built flatbed on it when I got it. It just wasn't finished and they put the fuel fillers up top right in the way.
I bought a used commercial built bed for a good price. It needs a little tlc but it's not bad.
It also has a built in goose neck which should be a plus even though I don't have one.
The unfinished bed is mounted with two pieces of c channel up front and slopes down in the rear where they bolted it straight to the frame.
The bed I bought has the mounting pieces bent where it was set on the ground so they need some work. They also look a little flimsy to me and I want to use thicker stock in their place.
It has five pieces of flat iron in what seems to be odd locations to me.
The front two set kind of far back from the front of the bed and the two rear aren't even with each other. And one odd one somewhere in between.

I haven't ever put one on before so I'd like to know the right way to do this.
Especially with the gn ball on it I would assume it needs to be solidly mounted.
It came off a 90 f250 btw.

So the new to you flat bed came off of a 90 f250 and you are putting it on a 91 F350 CC SRW? If so it will be a dirrect bolt on. If you want to strengethen the sub frame i would just beef it up by boxing it

 

[Fordsandguns]

Ok, I am finally getting around to putting this bed on tomorrow and I want to rehash this so that I get it right the first time.
I want to mount the bed as Midnight Rider suggested, with 1/4 inch steel plate on each corner welded to the bed and bolted to the frame with grade 8 bolts.
I currently don't have a rear tank in the truck and I want to mount the bed high enough that I can slip the filler tube in without pinching it far enough to cause filling problems.
Do I need to put a support between the bed frame and truck frame where the goose neck hitch is? Or will it be alright suspended from each corner?

 

[typ4]

you need 2 inches for the hose to pass thru and still fill. I am going thru this with my lowered utility bed install, front is going to be creative.

 

[Fordsandguns]

2 inches is about what the bed that is on there has and it was darn tight when I removed the tube when I took the bed out for having a hole in it.

 

[MidnightBlade]

When I put the dump bed on my truck, I cut some 3" C-Channel the length of the frame ( from back of cab to back of frame). Then we got 6 sheets of 1/4" plate and put 3 on each side, Under the C-channel you should weld another piece of the 3" C-Channel(about 6" long) somewhere near the front so that the sub frame will sit level (weld the small chunk of channel to the bottom of the subframe, not truck frame).

I'll post pics of mine tonight

 

[MIDNIGHT RIDER]

Ok, I am finally getting around to putting this bed on tomorrow and I want to rehash this so that I get it right the first time.
I want to mount the bed as Midnight Rider suggested, with 1/4 inch steel plate on each corner welded to the bed and bolted to the frame with grade 8 bolts.
I currently don't have a rear tank in the truck and I want to mount the bed high enough that I can slip the filler tube in without pinching it far enough to cause filling problems.
Do I need to put a support between the bed frame and truck frame where the goose neck hitch is? Or will it be alright suspended from each corner?

That all depends on the structural integrity of your steel flat.

It would not hurt a thing to put two additional brackets sort of centered in the goose-neck area.

I have seen the filler-tubes addressed in many different ways, none of them ideal.

On my personal truck, the front filler is accessed under the goose-neck trap-door, instead of poking across the frame toward the side.

The rear filler fits between the flat and frame and may or may not have a slight notch cut in the flat's channel to accomodate it; it has been a long time since I have even given it a thought.


I see many that have little trap-doors made into the floor of the flat, with the filler-caps located under the trap-doors; this is fine so long as you are not always hauling something that would be covering the trap-door when fuel was needed.


The biggest problem in figuring all of this out is that the factory tanks are not designed very well for use with a flat.

Outside the frame saddle-tanks are much better.

 

[MIDNIGHT RIDER]

Looking at this from another angle, instead of trying to route that aggravating flexible fuel-tank filler hose stuff to where you want it and using the factory pick-up bed type filler-caps, which always sort of look cheapy on a big heavy-duty flat, why not do this instead :


Decide where you want the filler-caps to be.

Instead of using the fragile plastic factory mess, use standard pipe with a standard pipe cap being the lid, anything around 1-1/2 to 2-inch should be fine.

You can weld this heavy pipe to the flat; it can be custom bent to weird angles; it can be cut, mitered, and welded into whatever shape necessary, so long as you keep the fuel headed down-hill.

Terminate the steel pipe about a foot away from the filler-hole of the tank and connect them together via a short length of the factory hose.


The filler-neck and cap on nearly all factory saddle-tanks found on mid-size trucks, such as F-700s or C-70s, is nothing more than a standard NPT pipe-nipple welded into the tank's top and capped with a plain old NPT pipe-cap that has had "wings" added to make removal easier.

 

[Fordsandguns]

Well, the guy that was going to help got called in to work so it is put off till sunday.

I agree that the filler tubes aren't the best suited to a flat but I'll use the bed more for hauling than I will the hitch. At least for now anyway, so I want to go in the general factory location. I like the idea of having a trap door and just going straight to the tank but that just wouldn't be practical for me.
Keeping the tube angled down is another reason to want a little more height on the bed.
I don't want to be ridiculous with it just up a little.
I think maybe a piece of two inch square tube welded to the bed on each side of the hitch to rest on the truck frame should support it. Then a mount on each corner of the bed bolted to the frame.