[gnicholson]

hi guys, long time reader of this site but 1st post. ive narrowed and modified quite a few axle housings over the years. my question has to do with gm housings like the 12 bolt made from 64 to 71. i have welded axle tubes on these housings in the past with mild steel filler rod with zero problems. no cracks etc. so i thought they were cast steel. other housings like the dana 60 would crack immediately if you tried that. yesterday i struck an arc and puddled a corner on a gm 12bolt and a file wouldnt touch it . in my book thats cast iron. my question: how was i able to weld these in the past with mild steel rod without cracking . normally i would use hastalloy w 309 etc on cast. Is there any grade of cast iron where you can make a successful weld using steel rod?

[gnicholson]

i mean i assume its nodular or ductile iron. even though it welded ok using the steel rod the weld is probably brittle although i havent had a failure. hoping some of you guys have some insight on this

[Arno]

Cast-iron can have a range of carbon content and on types that are on the low end of the spectrum the hardening effect of the welding will be less than on ones that are higher up on the carbon scale. Like any manufacturing process you may also find that the cases can vary quite a bit in cast metal composition based on age, location of manufacture, type, etc.

Also there may well be types of housings out there that were cast steel while others are cast-iron. Cost difference can mean that the cast steel types were used in more high end/expensive/powerful types while more simple vehicles got the cast-iron versions. A spark-test with a grinder would probably tell you a bit more about what you are looking at beforehand.

Eg: https://en.wikipedia.org/wiki/Spark_testing

Bye, Arno.

[Toggatug]

I've run into similar types of situations where I know I've done the same job 100's of times but then one unit will come in that is "different"

Usually I found with me it's that the unit is a aftermarket product produced who knows where using who knows what for material.

to be specific I can always tell if something is funny with the steel side rails of a radiator if they don't tin up in one go after sandblasting, usually leads me to think it a repopped unit where they decided to use galved steel or some form of coating on the steel that must be acid etched off for proper adhesion with the solder (usually why the radiators come in with popped off side rails and they don't look like the solder even hardly bit into the steel)

Not sure if anyone is pumping out replica rear ends etc but it is a thought to consider in my opinion.