Suggestions needed on shortening old truck frame

[jeepcj7]

I have a late 50's F600 Ford and need to shorten the wheel base on it. Drilling new holes and sliding the rear axle forward is not possible because the shape of the bottom of the C channel frame is different at the spring perches than it is in the middle of the frame. I have no issue with removing a section of frame out from the middle of the truck and then welding and plating the frame back together. Were I am having troubles with is deciding the best way to make nice straight clean cuts on the frame so I can splice it back together with out having to do a lot of grinding. Should i try using a swazall, use a cutting torch, use a plasme cutter, pay some one else to do it??? Any help is appreciated...

 

[Shield Arc]

I'm in the process of lengthening a bucket, I used zip discs to slice the ends of the bucket off. Sawzall was just to hard on my wrist, and to slow.
Here is a picture of a frame splice, with fish plate someone posted on one of the welding forums. This is how I would make the joint.

 

[kf4uda]

This was done a few weeks back on the TV show "Gearz" with Stacey David. He shortened a 67 Chevy but the process should be similar. This was also done on a TV show called "Trucks" but I don't know where to find the video.

You can watch the full episode of Gearz here:

Gearz Episodes: LMC Truck: Shortbed Conversion | Stacey David's GearZ

 

[RickB]

I would just use a torch with the tip against a piece of angle iron as a fence. Fast, easy, neat enough to clean up in seconds with a grinder. Done.

 

[PILOON]

Zip discs with a guide clamped in place works well for me.
I assume this is not a road truck as otherwise generally welding is not acceptable and would not pass inspection (they want rivets)
As mentioned above splice should not be @ 90 deq but slanted or in 'V's.

Good luck.

 

[RickB]

You guys that want to cut a truck frame (in four places) with zip discs ought to give it a try once.

 

[Arc weld]

I had a 4 ton dump truck shortened and they cut it at 90 deg's, however the most common method to shorten a frame is to cut the frame at a 45 deg and then butt it back together. You're going to have to do a bunch of grinding anyway so I'd just use a torch with a perfectly clean tip and a guide. Then bevel the cut for full penetration and put the fish plate on the inside. A long piece of heavy beam to clamp on the bottom will help line everything up properly. Do lots of measuring and make sure both sides are identical. I'd use 7018, maybe 8018 and do vertical up welds.

 

[Shield Arc]

Here is another drawing the same guy did, but with a 45-degree cut.

 

[Leyenda30]

I saw one done where the cut was made like a ship lap board. One half the height of the frame rail run a horizontal line about a foot or more then cut up on one end then down on the other. When you slide the two cuts together you have a longer stronger joint.

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[Gem99ultra]

Can't help you with the Ford 600 per se - BUT Stacy David on Gearz had a show on TV a couple of weeks ago (Gearz Episodes: LMC Truck: Shortbed Conversion | Stacey David's GearZ) showing in detail how he shortened a Chevy C10 long bed to make a short bed. Great show, and can be seen on the Gearz web site. Lots of good tips that I sure would not have thought of! And - his method eliminates having to drill a bunch of new holes and moving body mounts.

One thing that comes to mind though - you should not simply chop the frame straight line - it'll crack in the near future. Take a minute or two and watch the video to see how he's done it. He IS an expert on just about anything to do with automobile mods.