Do u have to use a special welding rod to weld the tubes to the carrier housing? Is it still possible to weld with normal welding like u would weld the perches on?

 

I used a mig with regular old wire to weld mine. Use LOTS of preheat and post heat. Get it hot slow and let it cool really slow. It's easiest to heat it with a map torch, then weld it, then bury it in sand.

 

You might want to take a grinder and just skim the surface of the tube and the housing where you're going to lay the weld in to help get rid of surface contaminants like oil, dirt, and rust etc. Preheat to about 500 degrees (that temperature will make a toothpick smoke when placed on it, so you know when you're hot enough). Weld around the tube without putting a huge bead on it. The bigger the bead, the more it will try to shrink when it cools and could be more prone to cracking. You could "peen" the weld with the pointed end of a chipping hammer right after you get done welding it. Peening is just hammering on the weld to let it stretch as it cools. Don't over do it, the pointed marks that it will leave in bead don't have to be real deep. If it's been a few minutes by the time you're done, throw a little more heat on from the torch you used to preheat with, then cover it with sand, clay cat litter, or even rock wool insulation to let it cool slowly. The slower, the better. The insulation works good because you can wrap one side of the diff when you're done and start on the other side. Nickel rod is the best to use, but low hydrogen rod like 7018 and yes even mig wire (ER70S6) and others, have all been used with success. The housing is usually nodular iron (not all though), which is more forgiving than grey cast iron that is used in blocks and transfer cases. The key points are clean, preheat, weld, peen, reheat if necessary, and cool slowly. If it does crack, it will usually be along the edge of the bead on the cast side, and out on the end of the diff housing, no real harm done, grind out the weld, get a different type of rod and have at it again. I don't think it will crack if you follow these steps. I've seen some done that didn't follow all these steps and the weld looked like a bird had been crapping on it, but they never cracked and held up well.

Good luck.

 

good info ^^^ but like you said at the end, a lot of guys just slap a bead on it and never have problems. i think a lot of people confuse nodular and grey cast iron. i'm gonna use a 6010 root on mine then mig it. 7018 is nice, but for it to hold properly, it needs to be in an oven to keep its moisture content down, and the mating surfaces have to be absolutley pristine. 6010 just burns through impurities.

 

True enough. Get the joint sealed with 6010 and mig on top should be good to go, just remember to cool slow.