: Hey guys,
:
: I have to apologize for being off-topic, but it
: looks like you all may know more about this
: topic than some of the other folks I usually
: deal with. I have some questions about
: crankshaft welding. I have a '49 Dodge
: pickup with a 230 cid flathead 6. I recently
: had the rear main seal surface welded, to
: get rid of rust pitting and build up the
: slightly undersized diameter.
:
: The rear main seal surface is just a bit larger
: diameter than the main bearing journal
: diameters. The seal surface is just in front
: of the flywheel flange, but not part of the
: flange.
:
: Anyway, my machinist removed about 0.030"
: from the surface, then proceeded to weld it
: with a "tri-gas" setup. After he
: finished welding it and grinding it, the
: region where the seal touches the shaft
: looked fine, but the adjacent material had
: some pits left over. I don't believe these
: were the typical weld pits, but rather I
: think they were remnants of the
: "valleys" between the weld beads.
: I didn't want to ask him to re-weld and
: re-grind, because he had already welded up
: the surface once before, but had ground it
: down too much and had to do it all again, so
: I was wary of over-welding. I decided to
: polish out a few of these "pits"
: and found a couple of them to be about
: 0.040" deep. I'm concerned that these
: irregularities can be stress risers, where
: fatigue cracks can start. What do you all
: think?
:
: The other issue is that my machinist did not
: pre-heat or post-heat the crankshaft. Will
: the metallurgy be adversely affected because
: of this?
:
: My crankshaft is a forged steel unit. The only
: thing I know about its composition is what I
: found in an old manual, which says it's
: "high-carbon" steel. I plan to
: make a few performance mods to the engine
: (dual carb intake manifold, headers, cam,
: high-compression head).
:
: The welding process he uses is a
: "tri-gas" setup. What can you guys
: tell me about this?
:
: I'm sorry for the long post, but just wondering
: if my crankshaft will come apart on me
: someday.
:
: Thanks for your info!
: Matt

: First, I don't know anything about this
: 'tri-gas' setup. Perhaps it is something
: relatively new.
: . . . Occasionally, we would have
: minor 'inclusions', which we would expose
: during the machining process. When we
: approached finish size(say, +.040" to
: +.060"), we would dye penetrant check
: the o/s journal. If any pits were
: 'developed', we would die grind the
: inclusion out until the hole was gone and
: then fill in the hole with solid weld. And
: repeat until it was right.
: Yes, preheating is a good idea.
: Air cooling should be slow and done by slowly
: turning the crank in the machine lathe.
: Yes, the inclusions can adversely affect the
: crank.
: Will any of these things cause you problems
: down the road? Who knows? How will it be
: used? It doesn't sound like an ideal job,
: but it might be OK.

: First, I don't know anything about this
: 'tri-gas' setup. Perhaps it is something
: relatively new.
: Up until about 15 years ago, I was a journeyman
: machinist. I worked in a marine machine
: shop, and one of the things we did was weld
: stainless 'liners' on forged steel propeller
: shafts, up to 2' in dia. and 48' long. We
: used a shaft lathe and a machine to feed
: flux-filled stainless wire. It is important
: to maintain the proper angle of the welding
: head to achieve proper overlap of the beads
: of weld. It is also critical to maintain a
: constant correct tangential speed of the
: surface of the workpiece, and the feed of
: the lathe apron that holds the fixture. You
: also have to thoroughly remove the slag from
: the previous bead before you lay another
: bead against it. Otherwise you'll
: encapsulate the slag in the weld, which
: causes all kinds of problems(some of which
: you guessed). Occasionally, we would have
: minor 'inclusions', which we would expose
: during the machining process. When we
: approached finish size(say, +.040" to
: +.060"), we would dye penetrant check
: the o/s journal. If any pits were
: 'developed', we would die grind the
: inclusion out until the hole was gone and
: then fill in the hole with solid weld. And
: repeat until it was right.
: Yes, preheating is a good idea.
: Air cooling should be slow and done by slowly
: turning the crank in the machine lathe.
: Yes, the inclusions can adversely affect the
: crank.
: If you had problems with rust(that you can see)
: on the surface before, you can have more
: problems with rust(that you can't see) in
: the new pits.
: Will any of these things cause you problems
: down the road? Who knows? How will it be
: used? It doesn't sound like an ideal job,
: but it might be OK.
: Just curious, why didn't you have it
: sprayed-up, or even chromed?

: Sounds a lot like welding-up and off-set
: grinding a stroker crank. The preferred
: welder used here is a "submerged
: arc" wire feed machined. As the name
: indicates, the welding is electric and done
: in a coolent to prevent heat and slag
: build-up.
:
: As for your "tri-gas" weld job, does
: the surrounding area show signs of excess
: heat build-up? (discoloration) Does the
: crank still "ring like a bell" if
: you tap the welded flange end with a hammer?
: (just a small tap, don't get crazy)
: If you want, have the crank re-heat treated or
: nitride surfaced hardened but be warned, it
: will bend and grow (or shrink) depending on
: the metal alloy and heat treatment process.
:
: As Bud points-out, these "weld-ups"
: take special equipment, knowledge and time,
: touch-up of exposed pits and imperfections
: is the major "hassel" with the
: welds. Remember that these surface
: imperfections are just that, surface
: problems. Yes with enough time and stress
: these can be the starting points for cracks
: but how much time & stress? (who knows)
:
: My view, try it and see what happens, worse
: case is that rear flange will snap-off the
: crank. (is this an automatic or a manual
: trans with a big flywheel / clutch?? I may
: think twice if there is a big flywheel
: spinning on that flange)
:
: For what it's worth, I have done 3
: "submerged arc" weld & regrind
: stroker SL6 cranks and every one of them has
: had some minor welding pits in the journal
: surfaces. None of these cranks have failed
: on me yet. (one has been in service for 9
: years)
: DD

: It is good to know that even the stroker cranks
: you've built had some left over pits, and
: they haven't broken yet.
:
: As you suggested, I am going to use this crank,
: but I wanted to get a bit more reassurance,
: as I would not want to get stranded out in
: the boonies somewhere. My truck is a '49
: Power Wagon, so I'll be doing some amount of
: off-roading with it, but nothing real hard
: on the engine.
:
: A couple of more questions: On your stroker
: cranks, did your machinist/welder pre-heat
: or post-heat, and are your crankshafts
: forged or cast?
: Thanks again! Dodge people are always helpful.
: Matt