So i was in my shop the other night working on my truck when an idea dawned on me. I am trying to put my Supercab on a regular cab frame. I still want to have a long box on the truck so I will have to extend the frame, witch is no big deal. The problem is that on the regular cab frame were the cab sits the frame rails are not flat (they swoop down) as opposed to the Supercab frame where the cab sits the frame rails are perfectly straight. One solution to this is a body lift witch I DO NOT want to do.

So what if I cut each of the frames 4 inches behind the rear cab mount and 4 inches in front of the front cab mounts, took the Supercab frame section and weld/ fishplated it onto the front and the rear of my regular cab frame where I cut out the regular cab section?

I will be using my truck as a DD but also as a work truck, it needs to be able to handle anything farm work can throw at it, especially heavy hauling, both with a gooseneck hitch and a regular rear hitch. My concern is the frame twisting/ breaking under load. Let me know what you guys think I'm looking to see what you guys think of my idea!

Thanks!

~Hunter

 

done properly it will be fine. they stretch frames on semi trucks. to make room for pushers ect. it will need to be properly welded and plated to make it safe

 

The best way to do this is called a z notch. After welding it you will want to fully box that part of the frame maybe even 3 to 4 inches over each side.

 

Look up "fish plate" for maybe a better or at least different idea to reconnect your frame after you lengthen it. Fish plate might just be for a repair of a frame. not to sure?

I would get the advice of a reputable welding shop, or race car chassis fab shop, but they will probably want to do it themselves rather than advise you on how to.

 

i think the best way to do it would be to take two frames, cut the one you intend to use for the front half of the frame at the back of the flat section of fame, then take your other frame and cut it off at the front of the flat section of frame then trim one end back for your overall frame length you need and attach the two frames together this way you only have 1 splice instead of two. after its welded together get some c channel that just barely fits ether inside or over the frame and extends well past both sides of your splice and bolt it too you frame on the flat sides and not the top or the bottom.

 

Okay cool! That gives me some hope!!

 

I have heard of the z notch, witch do you think I better a straight cut or a z notch? Does anyone have any pics of a boxed in frame?

 

Yeah I know what you mean, I have heard the term used many different ways. I will have to looks it up. From my understanding a fishplate is a piece of steel shaped like this <>, that is welded over a cut in a frame to strengthen the joint. I am lucky to have a good friend that own a fabrication shop that will be doing all of the welding for me.

 

I have thought about doing that also, the only problem that I have is that out if the two frames I have to work with one is a highboy and one Is a lowboy, the frame rails on the highboy frame are narrower than the lowboy frame. The frame rails wouldn't perfectly line up. I have seen the c channel method and am considering using it.

 

One thing you haven't mentioned is how your wheel wells center over your axle. I've swapped my 78 reg cab f350 dually onto a 89 f350 dually frame. I'll be doing a unibody style box and will need to relocate the wheel wells, something I was expecting to do. Just a reminder to measure everything twice and put it on paper. As for the frame there's nothing for me to add as you've already gotten good advice.

 

i saw this post in the what have you done to your truck today and thought of this thread, i don't know if i can quote from one thread to another but we will give it a shot here

this is how i would re-enforce your splice. the reason for doing it like this is to make it stronger without adding adding any stress points to lead to cracks in the frame. as the frame flexes and vibrates you want to avoid having it go from ridged to flexible and back again or it will add stress to these spots.

 

Okay that helps a lot! Thanks guys!!!

 

Seems to me like you could find a supercab chassis and just change it out that way for a whole lot less work and a whole lot better finish product.

 

That's what I was thinkin also Allen. The Rep gods got me locked out out
till I love some more.

 

I think that's what I'm gonna do, I have a F-350 supercab chassis the is rust free so I decided today to just use that. It ain't gonna be easy but it's doable.