Rear frame rot

[79 USA 1]

I was told years back by someone who worked for GM that there is a metal gauge change in the rear section of these frames by design as a crush zone. If you look at any A/G frame there is a seam center above the axle where the steel gauge changed out to the rear. The thinner gauge steel was designed to collapse and bend farther to absorb a rear impact should the bumper shock system not be adequate. Looking at the 73-77 Colonnade cars there is a unboxed kick up in the rear rails designed to bend as well in the 68-72 A bodies.
While I cannot confirm this as gospel truth for GM I do know years back when working a Buffalo Stamping, Ford used this idea incorporated into the Windstar front subframe rails as a safety crush zone.

 

[Ugly1]

I’m hoping to talk to a gentleman that worked for GM in the 80’s in a couple months. ( Doing a training program where I work) and want to ask him questions. Like what was said I would go with the fact that these are designed during and after the oil/gas shortage of the shortage of 1978/1979. Add in the “safety impact zones” thinning the steel for weight (bodies and frames)and EPA changes (HP went down the tubes more!)
Our cars of choice had no chance. It is also why cars like the Pacer,Gemlin, Horizon, Vega,Pinto… all died and are hard to find on the road. I won’t even talk about the Japanese cars for the rust from poor steel hardening ( rumors they used sea water)

 

[Baker7888]

Well boys, as promised …

 

[79 USA 1]

I’m hoping to talk to a gentleman that worked for GM in the 80’s in a couple months. ( Doing a training program where I work) and want to ask him questions. Like what was said I would go with the fact that these are designed during and after the oil/gas shortage of the shortage of 1978/1979. Add in the “safety impact zones” thinning the steel for weight (bodies and frames)and EPA changes (HP went down the tubes more!)
Our cars of choice had no chance. It is also why cars like the Pacer,Gemlin, Horizon, Vega,Pinto… all died and are hard to find on the road. I won’t even talk about the Japanese cars for the rust from poor steel hardening ( rumors they used sea water)

I look forward to hearing back on this just to verify or falsify what I have been told.

 

[g0thiac]

Well boys, as promised …

And you delivered. Nice to see the occasional weld p*rn 🤣🤣🤣👌

 

[Baker7888]

And you delivered. Nice to see the occasional weld p*rn 🤣🤣🤣👌

I am working on passenger side now. I was able to salvage the rail however the pockets were in worse shape than the driver side. Go figure. Almost there ...

 

[Ugly1]

Looks good! Should hold up well.

 

[newmexguy]

I look forward to hearing back on this just to verify or falsify what I have been told.

Average time to bring a new generation to market back then ran two to three years. That would have meant the redesigned '78 models were envisioned in either mid '74 or '75 for a Fall '77 introduction.

 

[pagrunt]

Average time to bring a new generation to market back then ran two to three years. That would have meant the redesigned '78 models were envisioned in either mid '74 or '75 for a Fall '77 introduction.

Keep in mind the 3rd gen A's came out in fall '72 instead of the planned fall of '71 release so our generation might of been on the drawing board earlier.

 

[john87442]

Very interested in this thread. My 87 442 has drivers side rear frame rot so I purchased both rear frame sections from summit thinking it will be better to purchase these and a good welder then having a frame shipped out from Arizona. Now I’m kinda questioning my logic, I haven’t stripped the car down yet and maybe there’s more damage from these NE Ohio winters then I have discovered.