|
I just use the 77 rod as I haven't had to repair anything "structural", you know, something bearing a great weight, like a rear end housing. I used AC (a Lincoln 225) and about 120 amps, maybe 140. You'll want to experiment a bit before you fix your first important casting, but I practiced a bit on an old motor block and went off to repair a broken transmission shift fork in my "H" transmission. It could have looked better, but it was my first repair and it worked out fine for me. I like to warm things up with a rosebud, do my welding, then use the rosebud to S-L-O-W-L-Y bring it down, and if you can put it in a sand bucket, or insulate it in a bed of clean kitty litter, that will help. A top and bottom layer of R-30 fiberglass insulation will slow the cool down as well. I probably take too many precautions there, but so far, I've never had a post-weld crack, weep, or seep, so I'm going to keep doing what I've done in the past. I have saved some had-to-replace castings using Muggy Weld. Here's a series of photos showing the broken shifting fork. I vee�d the crack and slid the parts onto the transmission shift rod to keep them in alignment on the common bore. Then I welded it, and while I was post-heating it, I made sure the fork did not hang up on the rod. Like I said, it might not be pretty, and my welds after that were much neater, but this one was my first, it was solid and strong, so I stopped. It looks nicer on the back side. i had my problems in that front recess, so I made a seconf pass, so the weld looks high. I could have ground that off, but elected to do that when I finally do the complete tear down later down the road. Sorry, these are the only photos I have. 
|
