When replacing a section of boxed frame, is it necessary to brace the butt welds?

[cjsgarage]

Hey guys. I'm just wondering if any of you has some advice.

I'm having to cut a section of frame rail out of a 1957 Ford to change the front suspension. The frame is factory boxed, and has large pockets for the coil spring to sit in. I need to cut the swelled coil pockets out of the frame and put in regular 3x4 box. The 3x4 box will match the rest of the frame. But when I've installed C notches and other frame pieces (after having cut out a section) I've always braced the butt weld. But that's been on c channel frame rail which got boxed after the bracing was done.

Is it necessary to brace a box tubing frame rail? Would that be accomplished by sliding in flat pieces on the sides and drilling a hole from the out side to plug weld the brace?

Am I being too ambiguous?

[raustinss]

Two pieces button welded are ok.....adding plates behind it is better...best yet would be to do some homework on cutting a frame and doing it like they do when they stretch a transport truck frame or a "z" ed hot rod frame...eg 2x3" tubing cut 1.5 " into the tube then move over 3"and make another 1.5" cut then cut horizontally between the 2. Kinda like a zig zag if you will.This spreads out the stress in the frame over a larger area. You can also add "fish" plates at this time too...either into the frame or outside

[cjsgarage]

The transport trucks idea was a good one. Saw some welding sites that showed how to stretch 'em. Looks like the Fish Plates are exactly what I need. I might end up using part of the new box frame I ordered and part of the original piece of the frame that is coming off the donor car set-up.

But just in case someone else was wondering: Apparently, it's way more important to run the fish plates on the top and bottom sections of the frame rail than it is on the sides. And it's also fairly important that the welds not be straight lines, hence the curves and such of a fish plate.

[cjsgarage]

There's a lot of frame rail to cut out here and I'm wondering if anyone has any input on my idea.

Here's the current frame set up, which is getting ditched.

And here's the side of it, where I need to make it work with the front end set up we have:


This is a crappy picture of what's getting installed. It's a Crown Victoria front end from a 2011 Police Interceptor.



The problem is, the Crown Vic lower control arm mounts way back from the "axle" centerline. 18 inches, to be exact. The Crown Vic frame rails are flat. The Ranchero's frame rails are not flat. So I need to make them flat to install this suspension on it. Which involves cutting the frame rails out pretty much to the firewall. Which is fine, I have enough tubing to do it.. but wondering if anyone has any advice on replacement design. I'm attaching a simplified idea of what I plan. Does this seem like a train wreck to anyone?

[Vince@Meanstreets]

that's going to be a fun one. and that's coming from me.


If I was doing it I would start way back past that body mount. Fabricated frame all the way forward from there.

[cjsgarage]

Vince,
I was thinking like this, to be more exact:




the body meets the frame rame not much farther past. I was going to follow the firewall down to the frame with new metal. Unless you think I ought to cut into the firewall to add frame rail?