First G Body, rear section of frame rotted out

[PowerSet]

Hey everyone, I'm brand new here, and as far as I can tell my only real big concern is repairing the rotted rear section of my frame.

The car is an 88 Monte Carlo LS.

Around the car there's little rust patches but nothing I'm too worried about, but behind the wheels the frame is just horrible.

I see the frame repair sections on Summit racing, and just want to be sure that's all I need.

I figure I'll get a whole kit of the body mount bushings, and replace the ones back there when I do it, and plan on doing the rest down the line.

Does anyone know how far forward the frame sections go? Is it behind the rear wheels, above them, in front of them? I just want to get an idea of how much I'll be replacing and assess whether there is enough solid frame to even do the job and not need to replace the whole frame.

Can anyone suggest a good walkthrough of the job? I've done some car work, but nothing like this. I plan on getting a welder and a bit of practice before doing the job, and since I'll need one down the line anyway. Are there any other suggested methods for the job? I assume the only way to do the job is welding, and not any of the jb weld stuff, riveting, or anything like that.

I appreciate any help or suggestions!
PowerSet

 

[seawolf18]

Its very common for the rear frame rails to rot out on these cars. All g-body frames are the same except the El Camino and Wagons. To replace the frame properly it must be exactly square. If not installed correctly, you car will dog leg and eat tires like they are going out of style. If you don't know how to do it, or have a friend that does, I would take it some where and have it done. You can get brand new frame rails here http://www3.sympatico.ca/conradlozier/ The best way to do it would be remove the body from the frame.

 

[-83MONTESS-]

Join the club with shitty rear frames. I took out the rear end the other night and almost puked at the amount of rust I found. Just gonna patch it for now :lol:

 

[tetomas]

Its very common for the rear frame rails to rot out on these cars. All g-body frames are the same except the El Camino and Wagons. To replace the frame properly it must be exactly square. If not installed correctly, you car will dog leg and eat tires like they are going out of style. If you don't know how to do it, or have a friend that does, I would take it some where and have it done. You can get brand new frame rails here http://www3.sympatico.ca/conradlozier/ The best way to do it would be remove the body from the frame.

To replace the entire rail it must be exactly square to keep alignment, when replacing the rear extensions they are cut behind the rear wheels, and would have no effect on wheel alignment. This is not to say you can just slap them in there, they need to be close or the body bolts will not go in. I agree the best way to do this is to remove the body from the frame. Take lots of measurements before cutting, make good welds, if you do not know how to weld do not use this project to learn, pay someone to do the final welds. This is also a great time to put on some POR-15 or something similar to prevent rust on your new frame extensions. Also a great time to box the frame rails, replace rusty brake and fuel lines etc. You do not want to have to lift the body off the frame twice!

 

[PowerSet]

At this point now that I've had a good look at it and it doesn't seem quite as bad as I originally thought, I plan out most of the rusted areas and patching it in while leaving the entire top which is still good and in tact, that way I won't worry about messing with the alignment or anything like that, and I consider it to be a repair within my limited experience. I will obviously drop the gas tank, and will most likely lift the body up off of the rear of the frame(I still need to look into what is involved in that, haven't looked up a good writeup yet as I am still a week or so from having the time to do it)

I just got the car, and want to keep it as cheap as possible for at least a month or two, just so I can get a really good assessment of what the car will need. Once I have learned a bit more about it, and have it baselined to where I'm comfortable investing, I will either have someone replace the whole section properly in a few months, or if my work is good enough to last for awhile I would like to do a frame-off semi-restoration of the car.