ok all, the insanity continues. Was out in the garage this afternoon making room for some "new" old parts that I'll be picking up in the near future for my 52 extended cab project, and I had a brainstorm. With the stretch I am doing, I need to lengthen my frame 20 inches to match the length I am adding to the cab itself.
While adding this length to the frame I was planning on going ahead and replacing all the frame cross members with either 2x4 or 2x6 3/16th rectangular tubing (depending on which cross memember it is), boxing the frame, adding new engine/tranny, and brake booster mounts, as well as X-bracing the entire frame (something I read in a recent classic truck mag). Pretty much going to make a rock solid 3/4, 1-ton frame.
My latest brainstorm though, is while I am at it, to go ahead and widen the rear half of the frame (basically from the cab back) 2 inches taking it from the stock 34 inches to a new 36 inches. I think the benefit to doing this will be allowing me to use a stock, aft axle gas tank out of a 70's or 80's full size ford truck.. which could give me either 19 or 38 gallon capacity depending on which tank I buy. Also, since I'll be using a Dana 60 rear axle and rear suspension out of the same 70's/80's truck I might not have to move the spring perches on the axle, as well as allowing me to use the stock sway bar.
Any comments on this? Anyone see any problems that I may have let myself be blinded to, or do y'all think its workable? Sorry for the long message, but I figure its been a while since I've rambled on with my ideas so I figured you were all about due. thanks. As always, comments and constructive critisism always welcome. Thanks

Jon

 

It might be hard to find some C channel the same size as your frame. The only C channel I could find was with a 1 1/2" flange. I could get various heights though. The C channel was ALOT heavier. To widen your frame you will need to make some cuts in the flange. Make one cut then make a pie wedge to fit in the crack which will make the channel angle out. A fews inches after make another cut removing a pie wedge. This should straighten it out and make your frame wider. I would have a professional welder weld the frame extension. When you are welding the crossmembers you will need to flip/turn the frame to weld them it. I would also get one of those adjustable straps and winch it tight to keep the frame tight. It might just be easier to get a 70's truck frame and just lengthen it. It is about 34" width in the front. Just find a F-250 Supercab Longbox. 158" WB. With that you may not have to lenghten it all.

 

As far as getting the steel for the frame, I'll have no trouble at all getting it. Through my dad and the company he is an engineer for, I can order pretty much anything I want, at cost. (have a nice thick steel catalog to look through). I know for certain I can get the rectangular tubing I want in the dimensions and thicknesses I'll need in mild steel. I will NOT be using C-channel, since the frame will be boxed anyway

I know how I would go about widening it, I actually have drawn up some schematics, its just a matter of making sure I cut the frame at the correct angles (guess that trig class I took will come in handy). The 20 inch extention for the frame will be added to the middle of the frame, not the end, and I would be doing the actual widening of the frame in this 20 inch section of new frame (so techincally I could make a straight cut in my frame, and not angle cut.. put the angle in the new metal)

When it comes to the welding, I'll be doing that myself. I have a pretty good clue of what I'm doing (worked in a machine shop for 2 years). When I have the actual stretch done on the frame, and comes time for the final welding and boxing, I'll strip the frame down as much as I can, and use 2 engine stands as a rotisserie so I'll be able to turn the frame as needed. I also won't be attempting the frame work until I buy my new MIG setup the end of the summer.

I guess I'm not concerned with my ability to build up the frame this way, but I guess I was just wondering if you all thought it would be worth it to take the extra additional work and widen the frame to allow for readily available gas tank and axle.

And when it comes to using a complete modern frame, that is not a concideration. My goal is to modify the original equipment parts so I can retain some of the originality of this truck. Not simply cover up completely modern setup with an old steel skin.

Jon

 

Well it seems you have everything handled. Just thought I might suggest it.

 

Jon

Moving axle spring spring perches is an extremely easy task and would not warrant re-engineering all the cross members or other major frame mods. There should be some fuel tanks that would fit without frame mods too. You don't have anywhere near the justification I would require to widen a frame.

Be careful not to turn this into something that will never be finished. Your stretch job is a handful already without adding to it. If you think you have the motivation to take it to completion, then knock yourself out if you really want to widen the frame. You'll no doubt learn a lot from the experience.

 

I notice you talk about using RHS sections for crossmembers. In my experience this is not a good move. You do not want an x-member to be torsionally rigid. They must be able to flex to allow the member to flex when running over uneven ground and cornering. RHS members tend to crack at the welded ends or end up cracking your chassis.I would suggest using an open section such as channel.

Dan