Frame rails

[JSabah]

It was brought to my attention that our vehicles (‘52-‘59 FFPW) actually have a frame inside a frame - 2 c channels nested together and that back when they were built had no rust preventative in place. Mine look to be solid and intact and being California trucks were most likely not subjected to as harsh conditions as some of you have. Therefore I’m not that keen on taking the frames apart just to have a look. Is there any way to test the integrity of the inner parts? I’m planning on a 4BTA swap and don’t know what the weight difference is (if any). These trucks will be used for primarily for city driving, maybe some highway for occasional camping trip in the mountains but no rock crawling. Thanks

[ChristianT]

Hi,
I have a 69 FFPW and did the full disassembly of the frame due to rust, mine where coated but there where rust in between the frames. The second half of the inner frame had welded in a new section, this was clearly coated. The front half had lots of surface rust but had traces of coating. This is a 69 so it is possible they did it different on earlier trucks.

[Doc Dave]

If you go with the 4BT, plan on adding a couple leaves.
Thats what I did; I started with a NOS spring pack and had a spring shop add 2 leaves for the extra weight. This was for my M37 build.
Similar issues for the civilian power wagon, and most of these trucks have tired springs now, so building a new pack is the way to go IMHO.
Also, there may be some interference with the oil pan so some extra height will help with that too.

[Matthew Welcher PWA]

A visual inspection is all that you can really do, do you see any rust or swelling in between the frame rails?
I have used and installed inner frame repair sections that work really well. It replaces the rear 4 feet or so of the inner frame section.
The 4BT is not an insane amount heavier than the flathead. As far as a weight consideration.
I agree with Doc Dave for sue, replacing the spring packs is the way to go.