Long bed to short bed conversion

[MarshMobbin907]

So I'm sure this is a repetitive topic, but I just like some baseline tips for a first-timer. I've watched quite a few videos and read even more Forums on this subject and a lot of people have different ways of doing it. I think I have the gist of it, new brake lines, fuel lines, short bed tank Etc. But one of my main questions is if I did this on flat ground with all tires inflated properly can I trust that cutting the frame and Welding it back together basing not only off measurements but on level a trustworthy technique? This is my project / daily so I really don't want to screw this up.
87 single cab, 2wd, 305 w/ 700r4

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[1987 GMC Jimmy]

I know this isn't what you want to hear, but I wouldn't do it if this was a vehicle you depended on for the simple reason of if it ain't broke, don't fix it. I understand the aesthetic appeal of a short bed, and that's two feet less space that it takes up, but it's your daily driver. If it were me, and I was gonna undertake this, I wouldn't cut, fab, or weld anything. I'd swap the cab onto a short frame that already had the bed, tanks, brake lines, fuel lines, driveline, etc. If you found one that had a 700R4 under it, that would actually be a fairly quick and painless ordeal.

 

[shiftpro]

This ^^^^^^^^^^^^^^^

Instead of switching cabs, why not get another truck like the shortbed you want? Unless your frame is hooped...
WHat could be better than a square body? TWO square body Chevs! A 4x4 and a 2X for summer shot haulin.

 

[shiftpro]

Having said that I am building a crew cab with a shortened frame. But no cutty weldy... just moving the perches and axle forward and then whack off what's left behind the rear spring hangers. In BC if the DOT sees a welded frame (other than welding on a hitch) you get to pay for a tow truck.
I've welded frames and ground and filled the frame flat, then entire frame was blasted, painted and undercoated. But from the inside of course the fish plating was visible.

 

[shiftpro]

So I'm sure this is a repetitive topic, but I just like some baseline tips for a first-timer. I've watched quite a few videos and read even more Forums on this subject and a lot of people have different ways of doing it. I think I have the gist of it, new brake lines, fuel lines, short bed tank Etc. But one of my main questions is if I did this on flat ground with all tires inflated properly can I trust that cutting the frame and Welding it back together basing not only off measurements but on level a trustworthy technique? This is my project / daily so I really don't want to screw this up.
87 single cab, 2wd, 305 w/ 700r4

You must be registered for see images attach

If you really need to cut and weld, level the truck on jack stands, four big ones holding the cab. With chalk or marker make a horizontal line on the sides of the frame behind the cab. I take it you will be cutting the frame just behind the cab? So use a 4' level to make this mark along the rear portion so after you cut it off and section the frame you can get it back to the same horizontal plane as you but up against the frame cut behind the cab.
If you're within 1/4 you will be fine. And it's not hard to get it much closer than that but just saying.
And without saying... but I'm saying it anyway, you need to know how to weld and cut and fishplate. You will need more than a 110v hobby mig welder btw.

 

[shiftpro]

Preheating the frame and post weld wrapping with a weld blanket to slow cooling is theoretically optimum. I did major welding on broken tractor frames without these steps, and they always held. Semi tractors with long wheelbase for hauling drilling rigs. 1/4 thick at least so multi pass with low hydrogen rod. After first pass hit with air peen hammer to stress relieve. Finishing cap lace uphill welding. Never ground and hid these welds...
Saskatchewan circa 1981-1988.

 

[74 Shortbed]

I helped a friend do this one time, there's a lot of work involved in this way more than what it's worth IMO, I would just look for a shortbed myself...

 

[Honky Kong jr]

I wouldn't do it, but I prefer long beds. Not saying I can't I'll cut anything but being a structural fabricator and crane builder I wouldn't hesitate if I felt the need, that being said not an ideal project for a novice with a tombstone and a few rods or a 110 flux core machine.

 

[shiftpro]

After my crewcab I want to build a shorty sbc 4x4 daily driver. 383 pane 5 speed 33" tires kinda thing. 20 mpg.
Na **** it... big block.

 

[shiftpro]

I cut the frame and that damn console still doesn't fit.

 

[Honky Kong jr]

I cut the frame and that damn console still doesn't fit.

 

[WFO]

If I find a deal on a short bed, I'll trade trucks with you. I like the color of yours, and long beds ride better.

 

[74 Shortbed]

If I find a deal on a short bed,

I have a rust free short bed, lol.

 

[harcorshe]

I'm in the process of doing a short-bed conversion and it's a lot of work, but to me it's worth it. This is not a daily driver so I've been able to take my time. (Although at this point the project is occupying all three garage spaces at the house and winter is coming...) I used four jack stands with 4x6x48 wooden beams across each pair to support the frame. One support under the rear of the cab, one behind the front rear spring hangers. I used a 3 inch "Z-cut" with an cut off wheel in an angle grinder. I also paid a mobile welder ($60.00/hour @ 3 hours). It lined up very nicely. Frankly, that was the most nerve-racking but actually the easiest part of the project.

 

[MarshMobbin907]

If you really need to cut and weld, level the truck on jack stands, four big ones holding the cab. With chalk or marker make a horizontal line on the sides of the frame behind the cab. I take it you will be cutting the frame just behind the cab? So use a 4' level to make this mark along the rear portion so after you cut it off and section the frame you can get it back to the same horizontal plane as you but up against the frame cut behind the cab.
If you're within 1/4 you will be fine. And it's not hard to get it much closer than that but just saying.
And without saying... but I'm saying it anyway, you need to know how to weld and cut and fishplate. You will need more than a 110v hobby mig welder btw.

Thank you for the tips, i really appreciate it. I used to be certified with 7018 in a few positions so I was going to go that route if I can find someone with the welder. Thought about Mig but I want guarantee that it'll hold up, plus my wife won't let me get a welder yet. Gotta love that military pay lol but again thank you