I have my truck ready to remove the bed and get started on the rear suspension. I have the Air Ride Tech triangulated 4 link and the Shockwave 8000 air springs ready to install. I have jacked it up at each end and the jackstands are literally at the ends of the frame. It's level side to side and the rear is a little higher than the front.

In a previous thread concerning boxing the frame it was stated that the frame was designed to flex to soften the ride. That's why the spring shackle points are spread the way they are, to distribute the load across the frame. It was also stated that I should have bags of sand for weight on the frame when welding in the boxing plates.

The questions I have are:

With the weight of the front clip, 289, C-4 and cab on the frame would I still need to have bags of sand on the frame?

With the jackstands that far apart and the weight of the rest of the components, do I need to be concerned with the frame bowing down in the middle?

Should the middle portion of the frame be supported also before I start welding in boxing plates?

I really don't want to weld a rocker into the frame. I don't imagine it would hurt anything but it would make the bed and cab have a wedge shaped gap between them.

I know to stitch the plates in short burts allowing the metal to cool between stitches to prevent warping. I plan to weld about 2 inches at a time and spread the welds out to keep from warping.

 

I just got done welding in a Corvette IRS and IFS in my 56 using FlatOut Engineering's kits. I used the front boxing plates and the rear weld-in bracketry but did not box in any more of the frame. I set the frame up on four jackstands positioned on the main rails (approximately at the front cab mounting points and the rear forward shackle mounting points). With the frame level I proceeded to make all my mods, checking the square of the frame as I went. I didn't see any bending or twisting as the result of the welding...I haven't heard about sand bags either, but I'm sure there's a rationale for them.

 

It won't hurt to have support in the middle of the chassis and it will ease your mind.

 

I've never heard of using sandbags to weigh down a frame when it's being boxed, but I've seen the distorted results of well-meaning builders having boxed a frame without putting it in a jig.

A professional chassis builder would tell you that the right way to box a frame is to pull the body off, completely strip the chassis down to the bare frame, and then rigidly clamp it down in a frame jig on a rigid table, preventing anything from moving.

When you're done, measure it from opposite corners (from left front to right rear, and from right front to left rear), to make sure that both measurements are the same. If it's off, what do you do then?

If you're interested, I wrote an article about building a frame jig on this page: Race car chassis builders

Dave
1956 Ford F-100 panel truck project