Crankshaft repair. Truly amazing.

[wierdscience]

Actually it does matter because they also stated welding and also why it really matters is this is beyond just welding - it's welding two pieces together,,, actually laser cladding is about as minimally invasive in comparison to the two other examples... of course the welding of two pieces together the extreme one...

The highest stress in any rotating shaft is at the outer most fiber, the lowest stress is at the center. ANY disruption of the outer surface is "invasive"

I believe you conveniently skipped this part;

"The highest torsional stresses are in addition to the web fillets AT THE JOURNAL AND CRANK PIN OIL BORES"

You know where that's at right? yup right were habib was putting his silly putty on -- remember the other guy he passed the crank too? the master oil bore driller - after the hole got plugged with the putty???

That's why the holes are always drilled in the neutral axis, at the LOWEST stress point.

lot's of speculations - lot's of assumptions --- but here's a total fact - he could be spot on with his rod choice and the vast difference in heat and cooling with just it will throw everything out of balance as far as hardness of the original material and the weld

any deviance of the weld material in either strength or hardness is a weaker crank as a unit, it will fail at where the crank material meets the weld....

keep in mind their not even going into harmonics/vibrations and frequencies let alone compounding the effects at certain rpm ranges

As John would say- Bollocks.

Guess you missed my post on the rare V/4 english built saab engine I had to have a journal built up and done? it's hack - it was a compact as all hell crank - I built it up - it lived, was it as strong as new --- No fuquing way - that's my point - was glad the POS held together long enough to move it...


So - just to clarify --- hack can be good, just depends on your situation ------- but not going to say it again - habibs crank is compromised in comparison to a original one piece, that's fact --- don't shoot the messenger boy... just telling things like they are....

So despite the evidence that an entire industry built of men and machines designed specifically for the task, according to you, they are all hacks....got it

[The Artful Bodger]

Guess you missed my post on the rare V4 english built saab engine I had to have a journal built up and done? ...

Yes, I am sure that was a quite rare engine as the engines Saab used were V4 Ford Taunus engines from Germany whereas the English built V4 was the the Essex engine which has a trifle bigger displacement. No wonder you would have had problems locating a replacement crankshaft for your "V4 english built saab engine"!

[J Tiers]

I had some of those V4 engines, in Saab 95s and a 96. Nice engines, and worked well in the Saabs. Still have a bunch of Saab parts, engine/tranny parts, trim, doors, fenders, seats and minor parts that need a good home.

[A.K. Boomer]

Yes, I am sure that was a quite rare engine as the engines Saab used were V4 Ford Taunus engines from Germany whereas the English built V4 was the the Essex engine which has a trifle bigger displacement. No wonder you would have had problems locating a replacement crankshaft for your "V4 english built saab engine"!

Yeah something like that --- all's you really need to know is pretty rare bird in these parts even at the time when the car was probably only 10 years old or so... hence the need for a hack crank repair.

[A.K. Boomer]

I had some of those V4 engines, in Saab 95s and a 96. Nice engines, and worked well in the Saabs. Still have a bunch of Saab parts, engine/tranny parts, trim, doors, fenders, seats and minor parts that need a good home.

What a bizarre vehicle --- my friends nicknamed it "The Amoeba"
I guess I had "the big block ford" as mine was a 1.7
Iv had some strange vehicles over the years but this thing was a doozie... 4 on the tree manual and you had to put it in reverse to get the key out (early anti-theft deterrent)

The engine was crude but fairly solid although I really don't like slinging around balancer shaft(s) if I can help it... had the freewheeling device - a one way roller clutch inside the tranny - pull a lever and your disconnected for coasting, get back on the throttle and it re-engages...

I did really like the huge tire size - lot's of little vehicles run too small of wheel size - so long ago but I think the rim size was 15" which gave it the ability to do better off road...

Lever action rear shocks that are total junk,,, I think they may have been the thing that was English on the car - it did have quite the compilation of parts from around the globe - bosch electrics I think - at least not lucas ------- don't quote me on all of this - talking about 40+ years ago

a tiny little rear facing back seat that stowed away - but the place it hinged out of doubled as a great beer cooler...

was going out with a smoking hot blonde at the time I bought and repaired that thing and we had a blast in that car, so im sure that's part of the fun factor I remember about it but it drove good - was a "sway baby" but that could have been remedied im sure... narrow vehicle - not with her but get another full size person in there and you were touching shoulders...

mine was tan, about 10 years ago there was another tan one in town for sale - I think they wanted 2,500 --- it sat for months I bet i could have got it for 1500 and should have snapped it up just to stockpile as im sure they are getting worth a pretty penny now...

For those that don't know what a Saab 95 looks like - I give you ---- the amoeba;

[A.K. Boomer]

The highest stress in any rotating shaft is at the outer most fiber, the lowest stress is at the center. ANY disruption of the outer surface is "invasive"

Bravo. will you please re-read what you just wrote? Disruption at the outer surface also occurs when putting two pieces of crank back together...

But I will add to this,,, Like JT your also just hell bent on "torsional stress" and yeah that's a factor but like iv been saying for many pages just one of them,

harmonic resonance can make a crankshaft self destruct in short order,,, and it does not always happen at the exoskeleton, in fact --- if there is a disruption at the core in material consistency that's where the stress can originate and then grow outward ---- and guess what? habib's little "garage repair" has core-disruption,,,

So what does all this mean? it means his repair can fail from the inside out that's what it means, all the ingredients for disaster this way, there's no "magic radius" on the inside of his welded part, there's just already a "cracked area" that abruptly meets the internal weld... harmonic resonance does not care about exoskeleton strength --- it's not "flexing the crank beyond yield strength" in fact its vibrating the inside just about as much as the outside...

it's vibrating it out of control like a tuning fork... therefor - any disruption inside the crankshaft itself that keeps the crank from "ringing as a unit" is an area of extreme stress,

And here's where things get really interesting --- the very same forces that can destroy a good solid crank due to it's ability to harmonically transmit and get out of control are the very same forces that can allow it to be tamed down due to the crank itself having a "complete signal" to the harmonic balancer...

Not so with habibs crank repair and yes I speak from experience of many times having a half dozen to a dozen used cranks (all the same) ready to go out to re-grind, and before they did we would pick them up - hold them with a bolt in the end, and ring them with a little ball-peen hammer, all in the exact same spot, they should sing like a freaking canary - and keep singing all about the same duration - and if not? if it's dead - it's a bad crank - there's something wrong in it's structure - most likely a crack - very rare but yes well worth the 15 second effort..
as good as magnafluxing? no - but a good cheap quick way of catching a bad egg...

Iv never rang one that was pieced together and had a dead end internal section - we did not deal with crap cranks intentionally - so I cannot comment about if I would have been able to catch it or not....

but make no mistake - habib's repair is not just compromised externally - it's also compromised internally, so harmonic balancer will not be able to do the exact same job like it does for a good solid crank who's "ring" is connected --- good chance the middle and other end of his crank will suffer and be able to resonate more while the front nose will actually be extra dampen'ed
That's the bad combination - guess what happens exactly where the high frequency ringing material meets the dead ? now your catching on....

"Four hungry children and a crop in the field" lol

That's why the holes are always drilled in the neutral axis, at the LOWEST stress point.

I believe your missing the big picture again - the very reason they are there to begin with is to grab some of the main bearings lubrication and hand it off to the connecting rod bearing's and since having a channel off to the side of the main bearing would just spill oil into the sump it's wise to put the holes in the middle where they can pick up and distribute the oil.... it's also wise to put the holes where they are in relation to being able to drill to the cranks throws for the rod journals --- hard to make drill bits go around corners and stuff right?

So despite the evidence that an entire industry built of men and machines designed specifically for the task, according to you, they are all hacks....got it

You can find that everywhere --- that's in no way proof that it's the right thing to do lol
there's dedicated people and machinery that re-weld aluminum cylinder heads --- iv met and worked with some of them - more patch work - can be done to varying degree's of success rates - call me funny but i like un-cracked heads,,, even little cracks between valve seats - "hey no problem we can take care of that",,, yeah problem because the valve seats have lost their press fit ---

more reputable places will weld the seats and shrink them to pull them out - then go in and totally weld the entire area and re-machine for proper press of new seats - much better except I don't like soft heads in that area and also same as the cranks don't like it where different material meets up -can cause problems and with heads it's not resonance failure but expansion rate failure... also - if the head was sipping coolant they may have stopped it for a bit but they did not get all the way in where the crack still remains inside the water jackets... No problem at first - but let it go through a couple hundred heating and cooling cycles...

To each their own - if you like stuff like that more power to you - I don't and know in either circumstance it is not as good as new and in some cases by a long shot - it falls short and is not worth the risk... also keep in mind with all the parts resources I have - there's no reason to pay someone crazy amounts of money to throw a hack repair onto it if I can spend 1/10th the cost for an "unbroken used part"... common sense right?

[deltaenterprizes]

How many OSHA violations did you see?

[A.K. Boomer]

How many OSHA violations did you see?

That depends if they are getting into "lung safety" as of late or not...

[J Tiers]

Bravo. will you please re-read what you just wrote? Disruption at the outer surface also occurs when putting two pieces of crank back together...

But I will add to this,,, Like JT your also just hell bent on "torsional stress" and yeah that's a factor but like iv been saying for many pages just one of them,

harmonic resonance can make a crankshaft self destruct in short order,,, and it does not always happen at the exoskeleton, in fact --- if there is a disruption at the core in material consistency that's where the stress can originate and then grow outward ---- and guess what? habib's little "garage repair" has core-disruption,,,

.......................

You really got wound up again..... Take a chill pill, calm down, relax, go for a ride, etc. Whatever it takes.

Torsional stress is not the only one which depends on the "outermost fiber". bending does as well. But, the nature of the entire construction of a crankshaft WITH the fact that the repair is to a main bearing, and not a big end bearing, means that bending is not the big deal here. Shear and torsion are. Just sayin, you know.... Take a good look at how that crank is supported and you will immediately see that, since there is support on both sides of every crank throw.

Sure-sure, there are a lot of "might" , "could", "can" issues. But you are approaching the entire thing as if it were to go into a high power engine designed to the max with FEA etc optimizing the design. Really overthinking the matter as if it were a race or aircraft engine.

Nope.... It's a smallish truck engine, probably diesel, since diesel is common most places outside the US. The repair location is almost the best case scenario. The options available to the truck owner are limited, since he is in a "colonial economy" and an economy where money is not easy to come by, and "new" parts are also not common.

Bottom line is that it is a very practical repair, and will almost certainly work fine for years of use. Something else is likely to take the truck out of service before that repair fails.

You want to have seventeen hissy fits? Look for the vids of folks making new cylinder liners, and pistons. If this was upsetting your composure to the extent that we see here, those will take the top of your head off.

Meanwhile, I suggest a book or three. One that covers the same sort of tech level shown in that engine would be " Internal Combustion Engines", by V. L. Maleev, from 1933 (McGraw-Hill). He was an engine designer, as well as a professor of mechanical Engineering. The section on crankshafts goes into quite decent detail about the various stresses, without needing (obviously) computers.

[A.K. Boomer]

You really got wound up again..... Take a chill pill, calm down, relax, go for a ride, etc. Whatever it takes.

Torsional stress is not the only one which depends on the "outermost fiber". bending does as well. But, the nature of the entire construction of a crankshaft WITH the fact that the repair is to a main bearing, and not a big end bearing, means that bending is not the big deal here. Shear and torsion are. Just sayin, you know.... Take a good look at how that crank is supported and you will immediately see that, since there is support on both sides of every crank throw.

Sure-sure, there are a lot of "might" , "could", "can" issues. But you are approaching the entire thing as if it were to go into a high power engine designed to the max with FEA etc optimizing the design. Really overthinking the matter as if it were a race or aircraft engine.

Nope.... It's a smallish truck engine, probably diesel, since diesel is common most places outside the US. The repair location is almost the best case scenario. The options available to the truck owner are limited, since he is in a "colonial economy" and an economy where money is not easy to come by, and "new" parts are also not common.

Bottom line is that it is a very practical repair, and will almost certainly work fine for years of use. Something else is likely to take the truck out of service before that repair fails.

You want to have seventeen hissy fits? Look for the vids of folks making new cylinder liners, and pistons. If this was upsetting your composure to the extent that we see here, those will take the top of your head off.

Meanwhile, I suggest a book or three. One that covers the same sort of tech level shown in that engine would be " Internal Combustion Engines", by V. L. Maleev, from 1933 (McGraw-Hill). He was an engine designer, as well as a professor of mechanical Engineering. The section on crankshafts goes into quite decent detail about the various stresses, without needing (obviously) computers.

WHHHHHHHHHHHHHHHHIZZZZZZZZ ---- that's the sound of something going right over JT's head lol


again,,,

re-read and learn or stop commenting --- or yet again your going to get slapped with that "stay away from that wheelbarrow Zirus cuz you ain't mechanical" phrase....

you are so far out there you are not even worth the discussion...

[J Tiers]

WHHHHHHHHHHHHHHHHIZZZZZZZZ ---- that's the sound of something going right over JT's head lol


again,,,

re-read and learn or stop commenting --- or yet again your going to get slapped with that "stay away from that wheelbarrow Zirus cuz you ain't mechanical" phrase....

you are so far out there you are not even worth the discussion...

You are making me spill the coffee laughing at you so hard.

You seem to have run out of technically valid arguments, so you have resorted to attacking the personality and not the actual discussion.

You REALLY need a chill pill..... take a break, come back when you have an actual point.

"not mechanical".......LOL.......

Your problem in this entire discussion is that you are living in an ideal world.... "spend money and fix it". That is a typical "mechanics's" point of view, and it works in a "first world" environment, such as we used to have in the USA. Those folks are not living in your world. You want a "perfect repair to new condition". They want a repair that works and does not cost a lot.

The pictured repair works..... it is done all the time over there. the guy has obviously done it before, and there are probably hundreds like him throughout Pakistan, Bangladesh, India, down into Myanmar and onward to Vietnam.. If it did not work, then folks would not do it, they would find another crank that at worst could be ground down to a size for which there are bearing shells, etc.

It's not that your points are "technically wrong", necessarily, although you almost certainly know no more about THAT particular engine and crank design than anyone else here. Your issue is that your arguments are pretty "absolutist", and "purist". Your arguments assume the worst, and make no allowance for "good enough".

It would be so simple for you to accept the idea that while of course welded crankshafts will have metallurgical and mechanical differences from new forged cranks, and probably are not as good as a new forged crank, they may well be plenty good enough for what they are used in. The original new crankshaft is almost certainly well in excess of the strength that is needed, for torque, harmonic vibrations, or whatever stress you want to bring up. It's surely overdesigned, and the repair does not appear likely to lower that margin by enough to matter.

If you want to learn about those stresses, look in a book such as the one I mentioned.

Not everything is a case of "if it is not perfect just like new, it won't work at all". If the guy who had the work done gets another year or two out of the truck or whatever, he's probably happy.

Your arguments here are fencing you in and committing you more and more to the position that the welded crank will fail before the guy drives it out of the shop. That's pretty unlikely.

For your enjoyment, I suggest the vids of folks repairing tires over there. Just don't have a stroke while watching.....

[The Artful Bodger]

Oh, how I long for the days when we had Evan to show us where we were wrong.

[A.K. Boomer]

Your problem in this entire discussion is that you are living in an ideal world.... "spend money and fix it". That is a typical "mechanics's" point of view, and it works in a "first world" environment, such as we used to have in the USA. Those folks are not living in your world. You want a "perfect repair to new condition". They want a repair that works and does not cost a lot.

That "perspective" thing has been talked to death ---- Yes yes bravo, the guy is doing what he has to do --------------- we got past that part of the discussion a long time ago, last many pages has been on how the repair is not as good as "new" and why it's not kosher to do in other area's of the world - replace the broken part with a non-broken one - don't try to glue it back together,,,
why in the world would you want to pay someone here huge money for a hack job when you can go to a You pull and pay and get a GOOD non-broken part for 1/10th the cost???

do try to keep up JT damn...

[A.K. Boomer]

Actually --- make that somewhere between 1/10th and 1/15th the cost to hire a hack to stick one back together,

just checked U-Pull&Pay's prices,,, Crankshaft; $34.99, Core charge (yes they will even give you credit for a broken POS two piece crank) $4.25

environmental fee; $3.92


These cranks are superior in every way in comparison to one that has been broken...

[IkeHarris]

It’s all about understanding what you can get away with. This applies to some hack repair or the original design. Each has constraints both economic and technical.

When a weld puddle solidifies the fusion zone is left in a state of strong tensile residual stress. Add this residual stress to whatever tensile load cycle is seen in service and you have a formula for early fatigue failure. The designer of the crank shaft probably was aware that the crank could fail late in life well after the warranty and the market expectations at about that spot. The designer certainly didn’t factor in that some weld repair would be done in this heavily loaded area of his/her crank.

The video: https://youtu.be/BA3BskhJD9k mentions at about 2:00 that a laser clad repair reduced fatigue strength by 60%. This to me is understandable considering the low heat input and high cooling rate of laser cladding would generate very high residual tensile stress. A conventional weld repair with its high heat input would stress relieve the fusion zone to a degree. You can see the journal glowing red in the videos. Not a furnace stress relief but good enough to get by.

Why would someone with a laser clad a crank journal making it junk?