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Hey guys, my father and i are beginning work on restoring his 86 CJ7. we have the body off and are down to the frame. We need to repalce the rear crossmemeber, and upon removing it, noticed that the last 13"'s of the frame on the driver side is rotted very badly. the rest of the frame is fine. Does anyone have any advice as to where to get a new section of frame, such as does anyone sell sections, or am i better off to look for one in a junk yard and just cut out what i need myself? Thanks in advance!!
 

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They sell plates that reinforce the rearmost section of the cj frame. Personally, I'd have a metal shop bend me up the outer and inner sections and have a skilled weldor do the work. I recently read some good advice on how to section a frame. They said to cut it in a Z shape so that there is no ability for a crack to continue vertically. I'll see if I can post a link.

Frame splicing Look at the 24th post for an illustration.
 

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No need to have it made up, that is a fairly straight section of frame as I remember,disassemble it until you find solid material to weld to then recreate what you just tore out using the other side for a patern. As tim said your final cut should be in a zig zag fassion. I like frame repairs to go inside the frame as opposed to a but weld.
 

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The key isn't the zig zag but that it puts the weld partially in shear and partially in tension. A tension only weld will crack again. You can make a vertical cut or a zig zag or a fishmouth or whatever shape you want. The strongest way is to have some strips of material crossing the weld with the welds running front to back. That will put the welds in total shear and be much stronger.
 

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[ QUOTE ]
I like frame repairs to go inside the frame as opposed to a but weld.

[/ QUOTE ]

Very sensible from a strength standpoint, but there's another consideration. The frame rusts out in places where two pieces of steel overlap. In that rear section the inner and outer halves of the frame rail overlap by about an inch at the bottom. Water invades the joint and promotes rust, and there's no good way to prevent it - paint can't penetrate, and sealers are only good for a few years.

If you stick a piece of steel inside your frame rail, or lay it on outside, you're creating a nice big area to hold water and promote rust. A good butt weld is very strong, and if you're really worried about it, you can do a continuous butt weld first, and then lay a small patch over it and weld it in place. If your welds are good, without pinholes, the area between the pieces will be permanently sealed and never rust.
HERE's a link to a writeup I did on the repair of my frame.
 

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my post on my frame repair

There are a few pics on that post from my frame repair. Believe me, if you think you have 13 inchs of damage you have atleast 20. Take a center punch and good size hammer and start hitting all over the place. You will be surprised what you will find. If the passenger side of mine rusts out, then i will cut the frame behind the tcase and make my own square tube rear section. We did mine at work and since then have done two others. Both of the other ones we used box tubing to replace the rusted out sections. Its getting hard to find a good non rusted out cj frame. If you find a complete good cj frame just use the entire frame.
 

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Take it from someone that does a LOT of frame cutting and notching...

First off, make brackets or take really good masurements of distances between holes, brackets, ect.
This way, when you section the frame you can get both sides square again.

Fix #1.
Make a 'Frame Section' that slips over your existing frame bad spot.
Have the local metal shop make a folded or cut and welded 'Repair Support Section' out of 3/16" flat plate.
If you want to save money, buy some 3/16" plate, and cut the sections out yourself. This will take time, but will save you the $45/hr or so shop time.
Then all the welding shop has to do is weld up your sections.
Slip it over the bad spot, drill some holes and bolt liberlly.

Fix #2.
If the rusted spot is in a place you CAN'T make a section for, then you will have to pull the body (or fenders), make sure the frame is WELL SUPPORTED, weld in guides or take masurements, and section out the old, damaged frame parts, and cut & bend new parts to replace them.
3/16" will be a little thick for this! Try and use sheet metal the same thickness (or a little thicker) than the stock frame.

Either way there will be a LOT of cutting, grinding and hand fitting work.
Remember, the more you make it fit now, the easier it will weld in, and the stronger it will be when you are done.

Don't forget to clean off the rest of the frame (or sandblast the entire frame) while you are working, you may find more damage, you can rustproof the good frame, and while you are welding under there & fabricating anyway, you might want to think about reinforcing weak spots and boxing in the frame while you have everything up and going...

You WILL need,
A power hack saw of somekind...
I've seen reciprecating saws, jig saws, power hack saws ect. used, and they all worked.
Recip saws seemd to work best, but blades are expensive...
Trying to do it by hand will kill you!

One of those little angle or cut-off grinders...
Doesn't matter if it's electric (more powerful)...
or Air powered, easier to get into tight places, but you have to have a compressor.
Safety glasses with side shields are a MUST!

Clamps,
A selection of small to medium 'C' clamps or body work sheet metal clamps are a must!
Some of the need for clamps is lessened if you have the capicity to spot weld, but you will still need several.

Some way to bend metal.
Harbor Freight has a small metal bending device used in a vice for about $20.
I used one for the first couple of years, and it worked fine.

Sand Blaster.
There is only ONE way to get large areas of really rusty metal clean quickly and throughly, and that's sand blasting.
White Silica sand is usually available for about $10/100lbs. at the local concrete & brick supplier, and the bucket blaster is available at Harbor Freight for about $20.
Two bags did my last frame, and several parts like the diff housings, steering box, bumper/brush guard, ect.
If you don't have an air compressor, one can be rented for a day or two for this project.
THIS IS WORTH THE TIME AND EFFORT, and don't forget to use rust converter, metal prep., paint and/or undercoat after blasting.
WARNING: Don't leave ANYTHING exposed to the sand blaster!
Face covering, arms and hands will be particularly beat up when you blast, so look like a space man when you go to blast.
 

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What's budget on this project? Careful when answering this question, this IS a Jeep we're talking about. The frame is the foundation that you are going to build on for, hopefully, years to come. Maybe the budget should include a solid(new) platform to start building from. I have an Advanced Frameworks frame. 100% happy. 99% bolt on. No welding, just drilling. Good Luck.
 

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I got tired of chasing rust on my frame also and ended up with an AFW frame also. Well worth the money.

I am the ultimate cheap ass and will pull a switch apart and clean it before buying a new one but remember Time = Money, choose one.
 

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What does the average AFW frame cost?
 

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I also have an AFW frame. Whats nice about them is that you can get some custom features if you want them. I had a 1.5" built in body lift installed (room for a future NC4500)and the rear frame rail driled for a YJ tub. You can get built in bumpers,shackle reversale, and galvinised coating if you want them.
All bolt holes were already drilled and tapped excepy for retaining clips for fuel/brake/vacume lines. Well worth the money instead of patching a badly rusted frame.
 
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