Suspension 1978 CJ7 Frame Rebuild

[Travwm]

I am restoring a 78 CJ7 and I welded new channel inside the frame rails. It came out really well EXCEPT: the frame rails twisted (of course) from the heat.

The brainstorm that hit me in order to straighten the rails is to use a Harbor Freight hydraulic porta power and some large all thread. It seems like I could lay it all out on a large table then mount up the Transfer Case /Transmission belly pan (6 bolts) to get started parallelling the frame rails. Then weld temporary cross members to the frame rails as needed where needed and use the porta power and all thread to bend and straighten the bends and twist out of the frame rails as needed.

I really don't want to buy a new frame as this one is really beefed up now and will last a couple of lifetimes.

Has anyone done anyone done this with any success before? I would appreciate any input!

Thanks in advance,
Bill

 

[TSB8C]

Only ever straightened one frame. I used a frame rack at a buddy's body shop. Good luck to you.

 

[Travwm]

I wish I had that luxury......Not!

If I don't figure out a better way I'll do it this way and let everyone how it went. :-(

 

[gert]

I have an MB frame that I want to straighten and my plan is to buy some I beam from the local scrap metal so I can have a very strong flat surface to work from, I also want to use a porta power to push/pull the frame til it’s right. I’ve seen some frame racks using large diameter all thread to locate and hold body mounts where they are supposed to be, please share your efforts and results


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[Travwm]

I will do that. I will start on it in March or April.

 

[Travwm]

I am restoring a 78 CJ7 and I welded new channel inside the frame rails. It came out really well EXCEPT: the frame rails twisted (of course) from the heat.

The brainstorm that hit me in order to straighten the rails is to use a Harbor Freight hydraulic porta power and some large all thread. It seems like I could lay it all out on a large table then mount up the Transfer Case /Transmission belly pan (6 bolts) to get started parallelling the frame rails. Then weld temporary cross members to the frame rails as needed where needed and use the porta power and all thread to bend and straighten the bends and twist out of the frame rails as needed.

I really don't want to buy a new frame as this one is really beefed up now and will last a couple of lifetimes.

Has anyone done anyone done this with any success before? I would appreciate any input!

Thanks in advance,
Bill

Update 7/7/22. Using measurements from a CJ7 frame print and CJ7 of the same year I went to work on the badly twisted frame rails. I first attached the 3 bolt belly pan for a starting point.
Then working on 1 frame rail at a time from the middle toward the outside as needed. It's important to get one frame rail straight in order to reference the other one off from it. I heat, beat, and welded in temporary cross braces top and bottom until I reached the ends of the frame. I used the porta power and heat to push and 3/4" pipe clamps and heat to pull together. Sometimes it's necessary to use a piece of chain with the porta power and heat to bend sections of the frame incrementally.
I still need to tweak it a bit but it's pretty close to where it needs to be now. It's been a lot of work but I have a frame much heavier than the original. If I were to do this again I would drill holes in the top and bottom of the outer frame parts then sandwich the new smaller u channel into it and do plug welds in the drilled holes.
IMPORTANT SIDE NOTE:
I will be using it for off roading. It's important to know that the original frame rails are designed of a particular guage with holes in specific locations in order to facilitate the transfer of energy incurred in a crash downward and away from the driver. If you're going to use the vehicle on road you would be well advised to just buy a new frame.

 

[gert]

I would definitely love to see pictures of your work


Sent from my iPhone using Tapatalk

 

[Travwm]

Update 7/7/22. Using measurements from a CJ7 frame print and CJ7 of the same year I went to work on the badly twisted frame rails. I first attached the 3 bolt belly pan for a starting point.
Then working on 1 frame rail at a time from the middle toward the outside as needed. It's important to get one frame rail straight in order to reference the other one off from it. I heat, beat, and welded in temporary cross braces top and bottom until I reached the ends of the frame. I used the porta power and heat to push and 3/4" pipe clamps and heat to pull together. Sometimes it's necessary to use a piece of chain with the porta power and heat to bend sections of the frame incrementally.
I still need to tweak it a bit but it's pretty close to where it needs to be now. It's been a lot of work but I have a frame much heavier than the original. If I were to do this again I would drill holes in the top and bottom of the outer frame parts then sandwich the new smaller u channel into it and do plug welds in the drilled holes.
IMPORTANT SIDE NOTE:
I will be using it for off roading. It's important to know that the original frame rails are designed of a particular guage with holes in specific locations in order to facilitate the transfer of energy incurred in a crash downward and away from the driver. If you're going to use the vehicle on road you would be well advised to just buy a new frame.

I'll see what I can do.

 

[Travwm]

I would definitely love to see pictures of your work


Sent from my iPhone using Tapatalk

I'll see what I can do.