Just ripped the old rotten bed off of my '73 I'm going to buil d a nice flatbed with an oak deck. What is the best way to level out the frame? Contoured 4x4 lumber or steel tube "Bed Mounts" that sit higher than the hump. I'm stumped here and pictures would be especially helpful. Thanks a lot guys

 

I am replacing framerails now which rotted out under the contoured wood. I will be doing the same thing when I get to that point. I was thinking mounting a backet to the frame, a nice heavy spring, and some heavy angle iron. My truck has a dump body though. I have not thought that far ahead, but in theory that is my plan.

 

I, too, am very interested in seeing the responses you get to this question.

I'm in the process of replacing some body panels on my cab, in order to have it painted. Before painting, the flatbed will have to be removed and I'm trying to figure out how I want to re-mount it after the painting. The previous owner simply welded the bed directly to the frame with a few metal tabs. It makes for a rough ride for anything on the bed (strapped down or not). I'm hoping to create a bracket that will elevate the bed just over the frame hump and possibly include a heavy duty spring for load support.

 

all the beds I've seen mounted on a regular frame truck use a 4x4 piece of wood trimmed to fit level. thats how mine is, but I don't really like it, the wood is cracked and moldy and Im' sure its holding moisture against the frame and the bed. The problem is that the wood shrinks and cracks and etc, and that leaves slack in your bolts, which are 3 or 4" off the frame, so the bed gets leverage on them. I plan on replacing it with some channel welded to the flatbed.

 

huh? who cares how "rough" the ride is in the bed, first off? are you hauling people around back there? lol. and second off, how do you think welding the bed to the frame would yield a "rougher" ride than bolting the bed solidly to the frame, the way most flatbeds, dump beds, and regular beds are attached? For that matter, besides a 1/4" puck of rubber with a steel insert, the same way the cab attaches to the frame as well?

Are you guys talking about the way they attach rigid beds like tanker trucks to tempered steel semi truck frames, with retained springs? this doesn't soften the ride of the truck, it just allows give so that when the tempered steel semi truck flexes, it doesn't tear the tanker open. I've never seen a flatbed mounted this way, because the steel flatbed can be rigidly fixed to the truck without any damage to the flatbed (and a flatbed will reduce any flex in that section of the frame anyway).

There is no point in using such a mounting system on a flatbed on a truck like ours.

 

Good point. I need to get a pic to show just how shoddy the mounts look. The tabs are just pieces of steel that are welded at each end, attaching the flatbed to the frame. As for rough ride -- I hauled a hot tub for a friend a couple weeks ago and every bump was exponentially made worse due to the heavier load. I do agree that a spring may be a bit too much for such a mount.

I dont like the idea of using wood to level the frame, so I will likely resort to channel steel to accomodate the hump, use bolts to attach the flatbed to the frame/mount, rather than welds. Here, I'd use bushings on the bolts between the flatbed and frame to absorb some of the contact between the frame and bed. Either way, it looks pretty crappy under the bed at the moment the way it is welded together.

 

The factory beds don't have bushings, but the factory beds have a lot of give in them compared to an aftermarket flat bed. A friend of mine told me he likes the wood crossmembers because they give a little bit and let the frame flex underneath the rigid flatbed. personally, I disagree, because there is no way it can "flex" unless its pulling or pushing on your mounting hardware. I am going to flip C channel so the C is up facing the bottom of the flatbed, cut it so that the ends are even with the truck frame, and weld it to the bottom of the flatbed. this way I can drill holes through the C channel and use a wrench on the outside ends of the frame to hold the bolt while I tighten the nut from inside the frame.

Also on my truck the rear recovery points are integrated into the flatbed because mine has a built in rear bumper, and I also plan on adding a rear receiver hitch that will tie in. I don't like the though of yanking or being yanked on with a block of wood and some carriage bolts being my means of being attached to my recovery point. Yanking a 500 lb steel flatbed off in the boondocks is not my idea of a good time. lol.

 

I built one in the early 80's for a brand D with rotten bed. To level and gain needed wheel clearance, I cut wood blocks to for the front of the "hump" and the back of the "hump" to get to the same level as the top of hump. Then I cut a full 8' length strip to go on top of the front and rear blocks and over (just touching) the hump. It was strapped down with plates under the truck frame and over the wood and 1/2" all thread.

I used un-treated wood (lighter). The front block started as a 6"x6" and the back as 4"x4" from memory ripped down to size. After cutting I brushed on wood preservative. The bed was 1" nominal oak on 2"x6" (nominal) oak cross members. It extended about 6" beyond the cab. The cross members were tapered outside the rails so the edge of the bed wasn't too wide, heavy and akward looking. The edge was piece was about 4" high including the thickness of the floor.

That bed was in hard service including daily rust belt farm service for much of its life until the frame of the truck rotted beyond repair in the early 2000's.

The edge wood and low stake sides were varnished oak and the bed floor was painted black. With a red cab, I thought it looked sharp. No pics. Sorry.

I am a fan of flat beds but I still don't mind that the original bed of my dent was repairable to a solid and attractive condition.

 

I leveled the frame for my flatbed by setting a square tube on the frame and adding tubing blocks under it with bolting tabs to existing holes in the frame. I tacked welded it and took it into the shop to finish weld. Its been 10 years since I built it but I'll see if I can find some pictures for you.

 

I guess i'm gonna try running a heavy piece of angle iron down each frame rail and use 2" square tube cut to level heights at each bolt location. with a long bolt run through the tube, frame and angle iron. Would this work? Should I use body mount bushings or just go metal to metal?

 

Well the frame changes widths so I cant just run a straight piece of steel down each side... Im going to have to fab up some brackets for the first set of mounting holes. They are only 33" centers and the rest are 35" and that puts me 2" off the frame for the front two brackets.

Then I can run my 3"x3" angle iron down each frame rail and keep everything squared up. What is the best way to accomplish the lift needed to clear the hump though? I can use 1.5"in tubing stood up on end and cut each set of holes a different height to achieve a level surface to run the angle iron on. I would then run bolts through the angle, square tubing and frame and tighten them together. That should keep everything tight. Do I need poly/rubber bushings or can i just go metal to metal?

 

I was at the junkyard today and they have started getting in a lot of "medium" duty trucks, like moving vans and single axle flatbed delivery trucks and farm/garden trucks, or utility trucks... pretty much every kind but tankers. I was thinking about this thread and I walked among them and checked them out. About half of them had the beds bolted to the frames on solid steel, and at least half, maybe more, all had wood blocks between the bed and the frame, even some of the really beefy looking flatbed trucks. Many had what looked like landscaping timbers run lengthwise up the frame between the frame and the flatbed, and the used giant U bolts down to the bottom of the frame. Lots had them running width wise, too. So I guess even on those bigger trucks a lot of them still use wood.

 

I put a tongue-and-groove treated fir bed on my 79 F250. Here is the process I used:

1. Mounted 4x4s to the frame in 3 places, 2 in front of the "hump" and 1 behind, a little over the width of the frame. I leveled the tops of the 4x4s with the top of the hump by notching each 4x4 accordingly. Secured with carriage bolts.

2. Once I had 4 level anchoring points, I ran two 4x4s, lengthwise, directly on top of the frame. Secured with carriage bolts.

3. Next I secured four 2x4 stringers width-wise on top of the 4x4 runners. I think I used lag screws, but I dont remember.

4. To complete the wooden frame, I capped the ends of the stringers with 2x6s.

5. With the frame complete, I laid down my tongue-and-groove fir planks.

6. I capped the back of the bed with a 1x12 secured to the ends of the 4x4 runners and the outside 2x6s. The 1x was necessary to fit the plate between the bumper and the wooden frame.

I hope this makes sense and you can visualize it somewhat. Once I got past the "hump" problem and getting the bed level on the frame, it was pretty self-explanatory.