Re: Busted crank repair
[Re: CMcAllister]
#3000556
01/01/22 08:26 AM
01/01/22 08:26 AM
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Joined: Jan 2006
Posts: 8,162 USA
360view
Moparts resident spammer
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Moparts resident spammer
Joined: Jan 2006
Posts: 8,162
USA
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On a serious note, instead of trying to repair a broken crankshaft by welding at the spot where it cracked, wouldn’t it be better to select two spots on either side of the crack and precisely cut out the bad section, and use a jig to hold in a replacement section during welding, tempering, and stress relief? The two spots where welds should be selected to minimize “stress concentration geometry” like corners, notches, etc. I once ordered machinists to try to hand polish the journal of a 60 year old Alco Locomotive Diesel crankshaft. The crankshaft was not broken or cracked, just needed to be reduced so an undersixed bearing could be used. It took several days of hand work, but in the end everything mic’ed OK. The engine then ran smoothly, without any odd vibration or noise. But... within a year the crankshaft suddenly broke at that journal without giving any sign of trouble. I will not say that amazingly precise work cannot be done with primitive tools in poor foreign countries. If you have never seen what comes out of the workshops of Darra Adam Khel it is amazing..... https://en.wikipedia.org/wiki/Darra_Adam_Khel
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Re: Busted crank repair
[Re: 360view]
#3000557
01/01/22 09:05 AM
01/01/22 09:05 AM
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Joined: Dec 2014
Posts: 6,229 ohio
ruderunner
master
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master
Joined: Dec 2014
Posts: 6,229
ohio
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Was that an early engine? Did it get the firing order update? Can't remember off hand if it was the 244 or 251 series that got that change.
Angry white pureblood male
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Re: Busted crank repair
[Re: 360view]
#3000558
01/01/22 09:20 AM
01/01/22 09:20 AM
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Joined: Jul 2003
Posts: 4,825 Holland MI Ottawa
2boltmain
master
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master
Joined: Jul 2003
Posts: 4,825
Holland MI Ottawa
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On a serious note, instead of trying to repair a broken crankshaft by welding at the spot where it cracked, wouldn’t it be better to select two spots on either side of the crack and precisely cut out the bad section, and use a jig to hold in a replacement section during welding, tempering, and stress relief? The two spots where welds should be selected to minimize “stress concentration geometry” like corners, notches, etc. I once ordered machinists to try to hand polish the journal of a 60 year old Alco Locomotive Diesel crankshaft. The crankshaft was not broken or cracked, just needed to be reduced so an undersixed bearing could be used. It took several days of hand work, but in the end everything mic’ed OK. The engine then ran smoothly, without any odd vibration or noise. But... within a year the crankshaft suddenly broke at that journal without giving any sign of trouble. I will not say that amazingly precise work cannot be done with primitive tools in poor foreign countries. If you have never seen what comes out of the workshops of Darra Adam Khel it is amazing..... https://en.wikipedia.org/wiki/Darra_Adam_Khel https://www.youtube.com/watch?v=yvYk0Ib0QdIThis is how they do it in Mother Russia! Fast forward to the 4 minute mark.
Last edited by 2boltmain; 01/01/22 09:21 AM.
Keep old mopars alive.
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Re: Busted crank repair
[Re: 360view]
#3001916
01/04/22 11:37 AM
01/04/22 11:37 AM
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Joined: Jan 2003
Posts: 2,094 central texas
krautrock
top fuel
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top fuel
Joined: Jan 2003
Posts: 2,094
central texas
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For the crankshaft it would seem you could make a custom jig from a scrap block to apply a measured force at each throw.
did you see the jig in the video when he was straightening the crankshaft? that seemed like plenty of force to test the welded journal.
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Re: Busted crank repair
[Re: Neil]
#3002205
01/05/22 07:11 AM
01/05/22 07:11 AM
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Joined: Jul 2003
Posts: 4,825 Holland MI Ottawa
2boltmain
master
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master
Joined: Jul 2003
Posts: 4,825
Holland MI Ottawa
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Keep in mind these engine parts are likely going back into a flat bed produce truck, and not a pro-mod engine, so the repairs are likely worth the effort, or he would not be wasting his time. Same for the effort of the people bringing him the broken parts too.
That guy has 10x the work ethic of the people at some of the machine shops around here. Smoke break every 5 minutes, constant cell phone distractions with the ball and chain, ect. Lucky to get your crank or block back in less than a month. You forgot to also mention- intentionally working slow to spill into some overtime. (That's how my co workers do it.)
Keep old mopars alive.
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Re: Busted crank repair
[Re: 2boltmain]
#3002271
01/05/22 01:14 PM
01/05/22 01:14 PM
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Joined: Jan 2007
Posts: 685 pennsylvania
poboyengineering
mopar
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mopar
Joined: Jan 2007
Posts: 685
pennsylvania
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That's not the first one he's fixed. That guy's got some mad skills.
It may be ugly, but it sure is slow.
Girls comb their hair in rear view mirrors and the boys try to look so hard....
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Re: Busted crank repair
[Re: poboyengineering]
#3004273
01/11/22 07:26 PM
01/11/22 07:26 PM
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Joined: Feb 2005
Posts: 20,272 PA.
pittsburghracer
"Little"John
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"Little"John
Joined: Feb 2005
Posts: 20,272
PA.
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That guy has almost unbelievable skills and patience. I’m betting those machines are spotless when he quits for the day.
1970 Duster Edelbrock headed 408 5.984@112.52 422 Indy headed small block 5.982@112.56 mph 9.38@138.67
Livin and lovin life one day at a time
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