3/4ton and 1ton trucks, pivot frame needed/worth it?

[IdaSHO]

Hey guys.

Not wanting to clutter up the pivot frame thread, I figured I should start a new one.
The other thread seems primarily for larger 2ton+ trucks anyways...

Im curious to hear your thoughts about utilizing a 3 or 4 point pivot frame on a light duty truck.
My rig is a 1996 F250 Powerstroke 4x4. I purchased it with a flatbed on it years ago, and am about to tear it off to refurb it.
Blasted, painted, rewired, new deck, and new LED lighting.

Im considering a 3-point pivot mount for it, but I simply do not know if it is worth it.
I dont think Ive ever seen or heard of a flatbed pickup breaking a frame, but Id like to cover my bases.

The flatbed is very strong and rigid. 6" C-channel.
The bed is currently hard mounted (bolted/welded) to the chassis.

I think my next step is to do some flex tests on it, to see just how much the bed is limiting the flex of the chassis. But Id like to hear your thoughts.

Thanks

[LukeH]

If the chassis is closed section ladder style I wouldn't have thought it was worth the effort. However we know youre going to have a wonderful time unbolting the front end of your flatbed and going off in search of some axle twisters. Load up a few sandbags to give a more realistic idea of a the twist under the real body load.

[LukeH]

Oh and you know how we like photos here....

[IdaSHO]

I know that the "OBS" (Old-Body-Style) Powerstroke F-series has been know for some pretty substantial chassis flex.

Here is a sample photo (not my truck)



The chassis these trucks run is pretty standard for the era. Heavy C-channel frame with stamped crossmembers, riveted and bolted together.


My primary concern is the integrity of the chassis. Millions and millions of these trucks are on the road still, and frame failure is, from what I can tell, nonexistent. So I think Id like to assume the engineers knew what they were doing. So I should encourage the chassis to do its thing, as designed and intended.

Second concern is fairly obvious. I dont want the truck to twist a camper into pieces....

I currently have the truck in the shop for tie rods and front suspension bushings. After the work is done, and the truck gets aligned, Ill start my flex tests.

Thanks

[IdaSHO]

Well, this truck is definitely getting some sort of torsion free mount.
I had the chance to test it a bit in the shop this afternoon.

With just 8" under the left rear, and right front, this is what Im looking at without any weight.



Doesnt look to bad from this angle...


This angle shows the twist in the bed. This would twist a camper to pieces in no time.



More to come....

[Ford Prefect]

Seems like a good idea.

[ujoint]

I'll be using a pivot mount on V4 for sure. Hopefully we'll be starting the bed construction next month.

[IdaSHO]

Okay guys, Im moving the updates of this project to my camper build thread...

http://www.expeditionportal.com/foru...74#post1129174


Starting at page 9, post #89


Thanks

[Fuzzydog]

How does the flex of the flatbed differ from the flex of the stock pickup box with a camper in it?

I ask because I am considering flatbedding my 95 F250 4x4 Powerstroke and it's primary duty is to haul my camper. I had resigned myself to the idea that twist shouldn't be a problem because the flatbed wouldn't be twisting any more than the original box would, and you don't hear about campers getting twisted to bits all over the place. But now you have me with doubts again....

[haven]

If off-road travels are on the menu, Slide in camper owners often choose spring-loaded tie downs, rather than bolting directly to the pickup box or frame. The springs allow for some flex of the bed without coming loose. Examples include Torklift Fastgun and Happijack.