Frame repair

This is my first post so please be patient. Newly acquired 79 cj5 project. Removed tub and find the rails past the rear shock brackets is rusted out. I have 2 spare rails. Is it adviseable to cut off the old frame at the rear shock bracket and weld on a replacement. The rest of the rails are good and it will really speed up the rebuild if I can weld on the back 2 feet on the rail??? I have accesss to some top flight welding but is there a trick to it if someone has done it before. Otherwise I'll remove the running gear from the rusty rails and put them on the replacement rails that are not rusted. Thanks a bunch.

 

Is it a boxed frame??

 

It is a boxed frame and the rust damage is worse on the inside of the boxed frame.

 

It can be repaired but you really have to make sure you know what you are doing here. You can sleeve it inside or out and reweld the section on it. What is going to be the main use of this Jeep? Show, offroad only, or just a driver?? You have to make sure it is properly welded and braced and you also want to make sure both sides are done the same. I have done it before but we made a whole new rear section out of square tubing that fit over the original frame, I can't remember what size. We never had any problems with it. However, this one was only used offroad so we weren't too concerned.

 

I also have a '79 CJ5 and am facing the same dilemna. I plan on beefing mine up with the M.O.R.E. reinforcing plates, althought I don't think those would do you much good as they're designed to go on the outside of the frame.

I do have one bad crack on the inside drivers side right behind the proportioning valve. I was hoping to be able to fix that by cutting out my own plate and tacking it overtop the whole thing.

 

Most all of the models I have seen with the boxed frame have the same problems with the frame rusting out because all of the dirt collects in the rear of the frame and causes it to rust from the inside out. It can be fixed but just make sure it is properly braced. To add a little strength you could also drill it and run a couple of bolts through the bracing and the frame once you get it tacked in place.

 

Thanks for the reply. This car will be a driver/hobby but will not be driven hard off road no rocks etc. Are there any pre built sleeves or other reinforcing products designed for this problem? This was a North carolina mountain car and the salt etc. has hurt it but from the shocks forward it is doing pretty good. The 304 is stronger than the 360 in my j10 and does not leak at the rear main. My son found a fibreglass tub on-line and if I can get this frame matter solved and with a few gallons of rust killer I'll be backon the North Carolina mountain roads. Thanks again for the help. By the way I usually hang out at the antinque tractor site. There is very little difference between a '53 Farmall and a '79 Jeep.

 

I don't know of any pre-built sleeves that you can buy. But then again, I am use to fabbing everything myself. You should be able to take some measurements on the frame and find some square tubing from a machine shop to fit it. Inside would be better visually but what ever you can find will work. You could also just plate it on the sides of the frame but if I did this I would probably tack everything in place and also bolt it where the plates are for safety's sake.

Do you got any pics??

 

http://www.mountainoffroad.com/catalog/FramePlates/framep.htm

http://www.autorust.com/k_41.html

 

Cool! I didn't know anyone was making these things. I'm glad I was sitting down when I saw the prices though.