The Stovebolt Site Forums The Shop Area General Truck Talk shortening a 3/4 ton frame

I seen a post on here a while back but can not find it on where to cut the frame on a 3/4 ton frame to make it a short bed.Can anybody give any help on this.Thanks.

just get a 1/2 frame, they can be found for very cheap.

I have a 3/4 ton frame thats been completed but would like to shorten it now.

I would be sure to cut out a section where there is enough length of the same dimension channel. That way you can butt the two pieces back together and weld them, then put a plate on the inside and completely weld it too. I wouldn't even be opposed to a plate welded on the outside either. If you're not sure about your welding skills, get someone else to do it. This isn't a place to skimp or let macho pride get in the way!

In short, measure twice and cut once. Good luck!

Where ever you decide to cut the frame be sure and cut it at a 45 degree angle. cut the section to be welded together at a 45 degree angle, grind the ends of the 2 sections to a V, put them together and then full weld the 2 pieces back together (inside and out). after cleaning the welds and grinding , then add a section of plate on the inside of the frame with the ends being shaped like a V. Full Weld on the inside of the frame taper the edges of the strap for better width weld.
The first question every one asks is why on a 45 degree angle ? The answer is the stress never gets a straight shot at the weld, the stress is spread out so the weld does not fail. Remember when you heat the frame you weaken it, This technique insures that the rejoined section of the frame is stronger than it was before it was modified. Kieth

"TRUCKS!" featured a '65 or so longbed which they cut down to a shortbed. They did not use the 45 degree concept. They "Z"'d the frame The area behind the cab and in front of the rear axle.
You can see it here if you missed it on TV.

http://www.powerblocktv.com/magazine/?pub=2ae59aac&page=30

What year truck are you working with? This can make a huge difference as to how to go bout shortening it, especially if it is a '47-'54 Advance Design truck (tapered frame).
Personally, I agree with Garandboy, shortbed frames are very common, no need to ruin a perfectly good and much less common longbed.

Its a 52.Was planning on cutting out 9 inches behind the cab or in the area of that.Thought I had seen a post of one being done this way posted a while back on here.Thanks for the info.

Check my pictures ,hope they will help.Frame is Z cut because the front section is not tapered like the rear .When the two are joined the frame fits ! Watch where you use that straight lazy cut !

9", why bother?
Leave it as it is and you have a tad more room in an already small bed.
Turning radius is good to start with, so no worries about the slightly longer wheelbase, you won't gain all that much by shortening.

What's the "reason" you want to shorten the frame?

Grigg

Well 9" is the difference in wheelbase of the 1/2-ton and the 3/4-ton (9-1/4" actually). He can put a 1/2-ton bed on it... and some like that short-truck look better... ??
Anyway, it's his truck to do what he wants.

Why do you want to do it?

TooMany2count
Pictures were taken with my phone .Lesson learned only use the camera .Computer ,phone and photobucket don't get along .The pictures will still show how to cut the frame .

Whether you shorten it or not you're getting unnecessary advice on welding one of THESE frames. The frame under your truck is made from mild steel. It is nothing more and nothing less so as long as your weld is done correctly, complete penetration, no undercutting, etc., you can cut it square, run your weld and be done with it.

Take it from someone who TIG welded for 4 years on automotive parts (including shortening and lengthening frames) and 6 years on jet engine parts for Eastern Airlines, a properly executed weld is actually stronger that the parent metal so as long as it's done right, there is no need for angle or Z cuts nor is there any reason for additional plates. Your greatest concern is that you make your cuts precise and line things up properly.

On the other hand, welding exotic steel alloys and/or heat treated metals is an entirely different story.

My 52 dump truck was lengthened 24 inches using 45 degree cuts with no gussets or plateing. After 58 years there is no signs of bending or cracking.So I would agree with Czechman.

My 48 2 ton frame had clearly stenciled on the inside something to the effect of "don't cut or weld on frame"
You'll find similar notes on most all if not every big truck frame today.

The old frames may not have been as special a steel as we use today for truck frames, but that is not an excuse to do a less than professional job.
Hire a professional if necessary, someone that not only can, but actually knows how to properly repair truck frames.

Still curious about the original post, what's the reason you want a shorter frame?

Grigg

If you look at what some people call welding I don't blame them one bit for that warning.

It's also possible that frames for heavier trucks are heat treated but such is not the case with a 1/2 or 3/4 ton frame.

Good link here to read and see the pictures http://www.customclassictrucks.com/techarticles/0707ct_1971_chevy_c10_tech/index.html

I have been in the used class 8 truck business for 25 years, build dump trucks and have stretched, shortened, or double framed hundreds of big trucks and this is how we shorten them. I did not see the tv show. I will take a look though. I have a complete 65 LWB frame that I am pulling out of a 65 chevy. I was able to find 2 swb frame in 2 days so I did not have to shorten it. Kieth