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Re: Busted crank repair [Re: CMcAllister] #3000556
01/01/22 08:26 AM
01/01/22 08:26 AM
Joined: Jan 2006
Posts: 6,742
USA
3
360view Offline
master
360view  Offline
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USA
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.

frown

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

Re: Busted crank repair [Re: 360view] #3000557
01/01/22 09:05 AM
01/01/22 09:05 AM
Joined: Dec 2014
Posts: 4,167
ohio
R
ruderunner Offline
master
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Posts: 4,167
ohio
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 guy
Re: Busted crank repair [Re: 360view] #3000558
01/01/22 09:20 AM
01/01/22 09:20 AM
Joined: Jul 2003
Posts: 4,346
Holland MI Ottawa
2
2boltmain Offline
master
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Posts: 4,346
Holland MI Ottawa
Originally Posted by 360view
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.

frown

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=yvYk0Ib0QdI
This 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.
Re: Busted crank repair [Re: 2boltmain] #3000576
01/01/22 11:22 AM
01/01/22 11:22 AM
Joined: Mar 2006
Posts: 8,860
MI, usa
dvw Offline
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dvw  Offline
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MI, usa
It’s amazing what determined people can do with so little. Not racecar stuff but obviously this isn’t the first one he has done. I wish I was this smart.
Doug

Re: Busted crank repair [Re: dvw] #3000582
01/01/22 11:44 AM
01/01/22 11:44 AM
Joined: Jan 2004
Posts: 6,134
fredericksburg,va
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cudaman1969 Offline
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fredericksburg,va
Somebody way back when made the first lathe, we’ve always been smart just didn’t have the education. A lot of geniuses from way back for thousands of years. We need to not pat ourselves on the back to much. This fellow USED that machine and did not push a button and stand back.

Re: Busted crank repair [Re: cudaman1969] #3000624
01/01/22 01:40 PM
01/01/22 01:40 PM
Joined: Sep 2003
Posts: 15,752
north of coder
moparx Offline
"Butt Crack Bob"
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north of coder
my old man useta' say : "pat self on back, break arm !" biggrin
i have never seen the roadkill guys weld wearing sheets and crocs............
i guess it's the end results that count ! up
beer

Re: Busted crank repair [Re: cudaman1969] #3001131
01/02/22 02:29 PM
01/02/22 02:29 PM
Joined: Jan 2003
Posts: 12,060
Omaha Ne
T
TJP Offline
I Live Here
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Posts: 12,060
Omaha Ne
Originally Posted by cudaman1969
Somebody way back when made the first lathe, we’ve always been smart just didn’t have the education. A lot of geniuses from way back for thousands of years. We need to not pat ourselves on the back to much. This fellow USED that machine and did not push a button and stand back.


iagree
And will add that we could likely learn a lot from them if we weren't so proud of ourselves. twocents

Re: Busted crank repair [Re: TJP] #3001492
01/03/22 01:24 PM
01/03/22 01:24 PM
Joined: Sep 2003
Posts: 15,752
north of coder
moparx Offline
"Butt Crack Bob"
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north of coder
it's always fun when someone pushes a button, stands back, and then hears that "expensive sound", followed by silence. biggrin
beer

Re: Busted crank repair [Re: moparx] #3001528
01/03/22 03:02 PM
01/03/22 03:02 PM
Joined: Feb 2010
Posts: 267
Mountain View, CA
6
68rrunner Offline
enthusiast
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6

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Posts: 267
Mountain View, CA
Originally Posted by moparx
it's always fun when someone pushes a button, stands back, and then hears that "expensive sound", followed by silence. biggrin
beer


Too true. We get that a lot here. A lot of CNC operators like to call themselves machinists these days. Put them in front of a Bridgeport or a La Blond/Turn Pro and they're useless.

The guy in this video has honed his craft.

Re: Busted crank repair [Re: 68rrunner] #3001599
01/03/22 04:14 PM
01/03/22 04:14 PM
Joined: Dec 2004
Posts: 2,327
Wheatfield, NY
Cuda340 Offline
top fuel
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Posts: 2,327
Wheatfield, NY
Anyone need a Hemi or Numbers Matching Block repaired?

https://www.youtube.com/watch?v=mi_NSFq0r8I


Last edited by Cuda340; 01/03/22 04:14 PM.
Re: Busted crank repair [Re: Cuda340] #3001721
01/03/22 08:04 PM
01/03/22 08:04 PM
Joined: Aug 2003
Posts: 39,019
Bend,OR USA
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Cab_Burge Offline
I Win
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Bend,OR USA
Originally Posted by Cuda340
Anyone need a Hemi or Numbers Matching Block repaired?

https://www.youtube.com/watch?v=mi_NSFq0r8I


That video makes me wonder what their labor rate is per hour versus buying another good use block work
Maybe we, our country, are living to high on the world's "hog" work


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: Busted crank repair [Re: 360view] #3001859
01/04/22 07:26 AM
01/04/22 07:26 AM
Joined: Jan 2006
Posts: 6,742
USA
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360view Offline
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Suggest how a repaired crankshaft could be tested,
without putting it in a running engine?

Suggest how a repaired block could be tested
without assembling an engine around it.

Seems a shame to put good parts at risk to test a welded up part.

For the crankshaft it would seem you could make a custom jig from a scrap block to apply a measured force at each throw.

Test a repaired block with high pressure water? (definitely not high pressure air - that is a bomb)

Nerve gas destruction plants have to have each weld x-rayed.
Constructors of the Bluegrass Ordnance Nerve Gas Chemical Neutralization plant - cheated on the weld x-rays.
The cost over-runs on that government project boogle the mind.

Re: Busted crank repair [Re: 360view] #3001916
01/04/22 11:37 AM
01/04/22 11:37 AM
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Posts: 2,076
central texas
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krautrock Offline
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central texas
Originally Posted by 360view


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.

Re: Busted crank repair [Re: krautrock] #3001969
01/04/22 01:45 PM
01/04/22 01:45 PM
Joined: Jan 2003
Posts: 17,868
Eagle, Idaho
Neil Offline
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Eagle, Idaho
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.

Re: Busted crank repair [Re: Neil] #3001978
01/04/22 02:08 PM
01/04/22 02:08 PM
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Posts: 3,889
nowhere
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Sniper Offline
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nowhere
Back when you could smoke at work all I ever needed for a break was time enough to get fresh coffee for my cup and the chance to offload the coffee I already drank. If you'll note in the video,he can still smoke at work, lol.

Re: Busted crank repair [Re: Neil] #3002205
01/05/22 07:11 AM
01/05/22 07:11 AM
Joined: Jul 2003
Posts: 4,346
Holland MI Ottawa
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2boltmain Offline
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Holland MI Ottawa
Originally Posted by Neil
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.
Re: Busted crank repair [Re: 2boltmain] #3002271
01/05/22 01:14 PM
01/05/22 01:14 PM
Joined: Jan 2007
Posts: 683
pennsylvania
poboyengineering Offline
mopar
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Posts: 683
pennsylvania
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....
Re: Busted crank repair [Re: poboyengineering] #3004273
01/11/22 07:26 PM
01/11/22 07:26 PM
Joined: Feb 2005
Posts: 18,932
PA.
pittsburghracer Offline
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PA.


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
6.143@110.85 mph
9.73@135.05 mph shifting at 6700 RPM
422 Indy headed small block
5.982@112.56 mph
9.42@138.27

Livin and lovin life one day at a time




Re: Busted crank repair [Re: 360view] #3004465
01/12/22 09:46 AM
01/12/22 09:46 AM
Joined: Jan 2006
Posts: 6,742
USA
3
360view Offline
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USA
Jay Leno should do a show with a title like:

“ You will not believe this successful repair”

Re: Busted crank repair [Re: CMcAllister] #3004604
01/12/22 03:26 PM
01/12/22 03:26 PM
Joined: Jan 2003
Posts: 17,088
S.E. Michigan
ZIPPY Offline
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S.E. Michigan
Really enjoyed this video.


Rich H.





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