Has anyone succesfully shortened a frame on a late seventies f150? I want a shortbox 2 wheel drive and they are hard to find, so I was jsut thinking I might try to shorten my frame, then cut the box and remove a chunk, and weld that back together too. I also know id have to get the driveshaft shortened, and brake lines and stuff like that.

 

Normally it is done with a "Z" section. Cut thru the top rail then diagonally across the frame then thru the bottom rail. The frame is usually "boxed" in that section also. Welding a frame is tricky and is best done by a professional that is skilled in welding automotive frames. This is different than just someone that can "weld". They have to know where to weld and how much. Just welding "everything" or "all around" is not correct.

 

My brother had a 79 shortened by a welding shop and it turned out pretty good for what I remember. He sold it a long time ago and another guy put a different body on it and the chassis still is in good shape. Has lasted up for a long time.

 

I'm a truck mechanic by trade and have shortened/ stretched many frames.As Torque1st stated it is normally done with a "Z" cut.After the cutting and welding the rail I like to have a liner or inner rail bent to fit inside the welded section. I try to work it out so the liner extends about a foot each way from the weld. I bolt, not weld, the liner in place using flange headed bolts and nuts.This allows for the frame to flex.If it's too rigid it will likely crack.I've seen several frames with short sections of plate welded over the seam.It seems to hold up well also but I have seen them crack.I've yet to see a linered frame crack.Hope this helps.

 

Excellent info!!!

 

As stated above The frame is easy part cutting the bed down and making look right sucks. I did it on a F350 made a shorty .

 

Thanks for the info guys, great to know it can be sucesfully done!

 

Years back I shortened a Travellal frame for a dune buggy. There was a foot between the front/rear springs. We took 4 1/2' out and used the 'cut-out to reinforce the frame. The buggy saw heavy use and was "jumped" quite a bit. As far as I know it's still running the Oregon sand.

 

So to get a regular box frame to a shortbox, do you guys think it would be as easy and cutting 2 feet out of the frame?

 

Are you planning to use a stock short bed or cut down a long bed? If your plans include using a stock box then I would find the wheelbase spec for a short bed truck.The difference between your existing wheelbase and the short bed spec is the amount you will need to remove.I would make the cut about 18 inches behind the crossmember that supports the rear of the cab.Before you make any cuts I would suggest you mark reference points on the upper frame flange on both rails.In some cases the rivits that hold the crossmembers in will serve the purpose.I mark 2 points on each rail.The first as far forward of the cut as possible without going under the rear edge of the cab.The second as far to the rear as possible but short of the upward curve in the rail.I use a square and a straight edge to ensure they are exactly opposite each other. I then use a tape measure to check the distance between opposite corners.The measurements must match.If not I go back to find and correct my mistake.Once the frame is cut I get the sections in place then use the reference points to make sure it's square.I double check and record all measurements while in progress as it's easy to make a mistake and a lot of extra work to correct said mistake.

 

Good advice. Im not sure what i am gonna use for a box yet. Right now Im just researching different options. For all i know getting it cut and welded might be super expensive too, so i might not do it yet.

 

it would be better if you could trade off or buy a short box.cutting a big box is alota work even if your a professional body man, unless you put on two new sides. the frame is easy i stretched them from as little as 3inches all the way up to 3 feet cut off front of bronco noses to put f 250 on them and i might be adding a box on the back of the bronco. boy too bad i wasnt near you. i have a beautiful short box i would swap for an 8footer . there real hard to find up here ,that are in good shape..

 

Sport truck magazine did a article on this in the march 07 issue. It shows step by step with photo's on what to cut and weld, as well as other measurement such as body mounts etc, you'll need to be aware of.

Granted, they did it to a chevrolet, but the proces and tips would apply to a ford. They however, bought a new short box because of the difficulty and cost of shortning the existing bed.

I looked and I couldn't find the article online, but you may be able to buy a back issue with the article in it.

 

Ok thanks