Upfitting a Fixed Body

[Steve Frazier]

I've noticed that when a fixed body is mounted to a truck frame there's a slab of hardwood between the body and truck frame. Does anyone know the purpose for this? The reason I ask is I'm converting the formerly dumping flatbed on my truck to a fixed unit. I'm concerned with both moisture being trapped against the steel and the wood rotting over time. Is there any reason I couldn't use a strip of hard polyurethane?

 

[CM1995]

I don't see why a strip of poly wouldn't serve the same purpose. Why are you converting it back to a regular flatbed?

 

[Steve Frazier]

The hoist frame has rusted beyond repair. I'm doing a very limited amount of landscaping now and don't have enough call for a dumping flatbed to justify the cost of a new hoist unit. Do you happen to know the reason for the wood?

 

[RonG]

I have seen that too and don't know the reason for it but I offer that the wood has a certain "compressability" is that a word?,that would be desireable to fasten against with the U bolts to secure the body to the frame.I don't think that steel to steel would ever be secure without welding it and even that might not be enough when the frame flexes as it was designed to do.Ron G

 

[td25c]

Yeah .... old thread but as RonG mentioned I also think the wood strips add a little friction between the steel frame & bed rails .

From a logistics standpoint in many cases the wood acts as a shim or spacer taking up the space needed to mount a scissor hoist as many of them mount on top the frame rail . On some truck frames you will have rivet heads sticking up around the suspension & cross member areas . We would drill holes in the wood slabs about 1/2" deep where it set on top of a rivet so the bed would set even on the frame rail .

 

[pushbroom]

The wood is also there to prevent major frame to body corrosion. On garbage trucks the bodys are mounted steel to steel but with large springs as so the frame can flex separately from the body isolating damage.

There is a good description in the Peterbilt body builder manual.
http://www.peterbilt.com/resources/Peterbilt Body Builder Manuals/Peterbilt Body Builder Manuals_Peterbilt Heavy Duty Body Builder Manual.pdf

 

[stondad]

Yes, the hardwood packing was used when the body was attached with U-bolts, but that has been banned in Australia for years.

Now we go steel to steel with plates down the side of the chassis rail and bolts through the chassis.

Tankers on body trucks will have four or six pads to bear the load with springs under the bolts to allow the chassis to flex without stressing the tank.