Re: 70 gmc DIY build
 

First stage complete and ready to move on to the frame. Broke the bed back down since I'm working in a 2 car garage and need space.

Re: 70 gmc DIY build
 

Frame was next. I know people typically cut the frame on these trucks under the cab but I didn't feel like lifting up the cab and trying to work under it. And taking the cab off was too much work. So I decided to make my cuts behind the cab and move the crossmember forward. Being a leaf truck made this easy but wouldn't be too bad on a coil truck either. You have to remove 8 rivets to get the crossmember out (12 on a coil truck) 2 of which have to come out anyway to remove the front bed mount. With this method you don't have to move the cab mounts forward requiring removing 8 rivets and drilling 8 holes. I chose to just weld the crossmember back in instead of bolting it, easier and stronger. Laying out your cut lines is simple. Just pick any spot make a mark then make another exactly 12" from your first mark. Then make the other side match. So long as you're taking exactly 12" from each side things will line right back up. Back of the frame is easy. Mark and drill the rear bed mount bolt hole up exactly 8" then cut 8" of off measured off the end of the frame. Next post I'll get into prep welding and fish plates.

Re: 70 gmc DIY build
 

Ugh, I should not have opened this thread. Its like watching a great show and all of a sudden ... Previews for next weeks show ... Noooo, I want it now!!

Great thread and cool build. Lots of very good info in here!

Re: 70 gmc DIY build
 

I agree!!!

Dad gum welding on bed looks SO good, might be able to smooth over the welds, body work them, and TOUCH UP THE PAINT....Job well done!!! On everything!!!

Re: 70 gmc DIY build
 

x2!!!!!

Re: 70 gmc DIY build
 

Thanks I add more when I remember to.

Yeah a good body man could get them straight enough to paint. I've seen a few guys blend in the factory paint and do a great job.

Re: 70 gmc DIY build
 

So onto welding the frame back together. First a little background on myself. I've been working in industrial steel fabrication more than a decade and have welded on everything from oilfield trucks to pressure vessels for refineries. I chose straight cuts because I see no need for the "z" cut. I've done straight cuts in various types of materials that hold 10's of thousands of pounds so it's good enough for a half ton pickup.

So here's a bit of a P.S.A on what I feel is the proper way to do it. First thing you need is a welder rated for the thickness you're welding (220 volt machine). You need mig wire with shielding gas. I'm using 75% argon 25% co2 with .035 er70s-6 wire. Even though I have welding experience I took the pieces of frame I cut out and cut them to make multiple joints to practice on which I highly recommend. It will allow you to get your machine dialed in and work on your travel speed.

When it comes to prepping the 2 halves of the frame you want to put a bevel on the inside of the frame rails almost to a point and leave about a 1/16" gap between the front and rear rails when they go back together. This is to achieve full penetration welds. You want to weld the inside of the frame rails first then grind into the back side of your welds on the outside of the frame with an 1/8" grinding disk to make sure you're achieving full penetration and welding to nice clean steel. When you knock down your welds don't go crazy, stop when they are flush.

First picture shows the prep and fitup you want. Second shows how running a few practice joints helps get things dialed in. My first weld had porosity from the ceiling fan being on. If you get any porosity you need to grind it completely out before continuing. Third picture shows the penetration on the outside of the frame. As you can see the first weld didn't burn all the way through the second and third is what you're looking for. Last picture shows the first weld ground into the weld then the weld after finishing.

Hopefully I wasn't too preachy or long winded but I see a lot of sketchy scary welds on frames. If cutting down your truck is your first welding project I strongly recommend watching some quality how to videos and getting some scrap to practice on before moving on to yourframe.

Re: 70 gmc DIY build
 

Great info! Also your work looks fantastic. Keep er going:metal:

Re: 70 gmc DIY build
 

My mind is blown... wow

What an amazing job

Speechless isn’t the word, but it’s close to it

Re: 70 gmc DIY build
 

Thanks. Progress has slowed lately but not caught up on posting.

Thank you very much, though I think you are giving me far too much credit. Lol

Re: 70 gmc DIY build
 

Now that I'm off my soap box from my last post here's the finished frame. Made sure everything was square and level and welded it up. Made a fish plates to hold inside the frame for added overkill.

Re: 70 gmc DIY build
 

Looking good, killer skills on that bed, keep going and hopefully I will see you cruising it around the area, provided they let us still drive around ;)

Re: 70 gmc DIY build
 

Thanks. We'll be fine this is Oklahoma not California.

Re: 70 gmc DIY build
 

Had my driveshaft shortened and had them put in New u-joints and carrier bearing. I didn't measure just told them to take exactly 12" out of the front shaft. I ordered a intermediate parking brake cable for a short bed and it fit perfectly. Was concerned they were different for coils and leafs but apparently not. New rubber brake hose and wheel cylinders and it was ready to move under its own power. So much more room in the garage now.

Re: 70 gmc DIY build
 

Why not a 1-piece drive shaft?
Just curious

Re: 70 gmc DIY build
 

2 reasons. I plan on upgrading to a 700r4 at some point and can have a new shaft made then. That and I'm not 100% on where I'm going with my suspension. I'd eventually like to bag it and I hear a 2 piece is better for that.

Re: 70 gmc DIY build
 

I'm still stuck on how good of a job you did on those bed sides, where did you get the ideas or learn how to do it?

Reason I'm asking is, I have already made my long bed into a short bed but was just going to buy the new sides but seeing how well yours turned out I may give it a try and save myself a bunch of money.

Re: 70 gmc DIY build
 

Yes the 2-piece driveshaft with the rear slip yoke is perfect for the extreme drop of a frame laying truck. (Like Porterbuilt, GSIMachineFab, ChoppinBlock,etc. )
But mild dropped/bagged trucks with just a bolt in c-notch (no step notch) work better with just a 1-piece.
This is my favorite build on this forum!

Re: 70 gmc DIY build
 

Long time Lurker, infrequent poster here...I had to subscribe to this thread. That is the finest welding I've seen.

Re: 70 gmc DIY build
 

I did a ton of research even before I bought this truck. There's some great information on this site. I also looked at tons of pictures to try to figure out in my head how they did it. One of the best out there is a guy who goes by metaloxfab on Instagram. Spent tons of time looking at his pictures. He actually released a how to video, right after I did mine of course. Lol. If you already have most of the tools to do it I say go for it. Otherwise it might be cheaper to just buy bedsides.
For now I'll probably just go for a static drop like a 4/6 or 5/7. And thanks I really appreciate that.

Thanks. I started learning to weld when I was 14 I'm 36 now but it's been a long time since I've done it all day every day but I guess it's like riding a bike.

Re: 70 gmc DIY build
 

so with the frame done it was time to put it all back together. But I had to decide what to do about the trim. The upper trim was easy, just remove the end piece cut off 12" and put the ends back on. I could have searched for used lower short bed lower trim which could be difficult to find in good shape, buy repop trim that would be too shiny and of questionable quality. Or try and cut down my trim. I had seen people cut theirs down at the wheel opening which leaves the ends open and doesn't look right. I decided to cut it at the front and back. My trim wasn't in great shape and had a few screw holes (in the parts I cut off) so I cut them off leaving a little extra to fold over. I used a piece of wood I shaped as a buck to hammer against. If a guy was good with a router he could make a nice grooved buck to perfectly match the trim. I'm not that guy I stick to working with steel.
Stainless doesn't shape well but they didn't turn out too bad. First picture shows original ends compared to new ends.

Re: 70 gmc DIY build
 

Man.... Skills.

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Now you are just showing off :)

Great work. Patience is such a key to all of this and I don't have much of that.

Re: 70 gmc DIY build
 

X2, nice work and looks great.

Re: 70 gmc DIY build
 

Thanks I try.
Sometimes I feel I don't have as much as I used to. Gotta walk away sometimes or call it a day and start fresh next time.
Thanks I still say the pictures are flattering but I'm just building a fun driver.