I got it for general rebuild and found all the damage, and the new owner wanted it all kept "numbers correct" for his Concours-style resto, so dug/ground/drilled out all the JB Weld and had the holes welded closed, then had the chain hole welded shut, then had the surface of the lower case welded up/milled back (3 times each) until the case would close again, and seal.
There is no possiblity that the location of the crack in his pictures could EVER cause enough distortion to make the cases not close. I'm not sure what situation you had, but the repairs must have been significant (I'm thinking the dreaded case crack from a broken drive chain) to need to re-machine the mating surfaces. And a competent machinist would have welded above the mating surface then either milled or fly-cut the repaired area flush to the mating surface. Job done. 3 times? What the Ef?
There is so much internet mythology to the "welding distortion" with aluminum that unless you weld, you should refrain from advising people (not directed at you, Mark, anyone in general that opoines). Aluminum is a major heat sink. It takes an incredible amount of heat to staturate these cases that TIG welding up a crack will never produce sufficient damage.
My original counsel to jig it up was due to misunderstanding where the crack was from his picture. Where these pictures show, its no big deal. A 30 minute repair, both sides. It would take longer to pack and drop off at the shipper than to repair it.
Yeah, the back-and-forth trips for repairing those precious cases were due to not knowing 'how high' to weld them, and the sagging that occurred in the web area in front of the sprocket. The lower portion of the area below the break-in was also dented somewhat, which complicated things: the 1st pass was to build up the whole area about 3/4" thick, then reshape (with a coarse hand file) it on the inside-the-cases side so that a wall could be built at all. That was the 1st effort, and it cleared the countershaft gears' teeth tips by 1mm less than a 'normal' case, but that was the best we could do and get a seal, because there are only 2 bolts in that area in these early ones, not 3. Then we built that whole section up until it was above the case parting line and I had it milled back down (flycut) to match the rest of the case. There were several tiny airholes where impurities in the case material near the welding areas were still contaminated with oil debris, so in the last pass those were all welded up proud again (8 of them, IIRC) and re-flycut to match the rest of the case. Tedious, but it worked!
