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nsracing Samba Member
Joined: November 16, 2003 Posts: 9467 Location: NOVA
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Posted: Sun Sep 19, 2021 5:30 pm Post subject: Re: Crank snapped in two. Oil starvation or crank flaw? |
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It is an old crankshaft that had been cycled over several its lifetime - bound to happen. I say that part gave itself a long service life.
Looks like a Demello work - I like their work a lot. |
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Braukuche Samba Member
Joined: September 03, 2004 Posts: 11004
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Posted: Sun Sep 19, 2021 5:46 pm Post subject: Re: Crank snapped in two. Oil starvation or crank flaw? |
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I don’t know why anyone would use a 30-50 year old crank these days when you can buy new ones. Same with cases, these parts are way to old and gone through too many wear cycles to withstand too much abuse. A stock build yeah, or if you have a 25 or 36 Or 40HP but a 1600 based performance build offers too many good new alternatives. _________________ Go Reds! Smash state!
Retirement is here!
1956 Ghia
1959 SO-23 Westfalia
1960 double cab
1960 Baja Bug
1963 stretched double cab
1962 Golde sunroof Ghia
1963 356 B coupe
1963 Notchback
1967 21 window less rusty now |
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modok Samba Member
Joined: October 30, 2009 Posts: 26787 Location: Colorado Springs
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Posted: Sun Sep 19, 2021 6:04 pm Post subject: Re: Crank snapped in two. Oil starvation or crank flaw? |
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"new" cranks are a better deal at the moment, YES, but
Keep in mind that it wasn't this way in the past, and the future is unknown.
There is a saying about
When things seem too good to be true....
or, it is fortunate your crank broke during... a time of crankshaft abundance. |
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Shane Tuttle Samba Member
Joined: February 02, 2011 Posts: 173 Location: Arlee, Montana
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Posted: Mon Sep 20, 2021 11:37 am Post subject: Re: Crank snapped in two. Oil starvation or crank flaw? |
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Quote: |
I don’t know why anyone would use a 30-50 year old crank these days when you can buy new ones. |
The alternative, for the most part, is a crank sourced from China. Their cranks have history or breaking as well. And they're not 30-50 years old.
If I can reasonably and economically do it, I won't buy anything sourced from China.
DPR uses original German forged cranks. Arguably, it's a better material to use. Jose is a small business that provides high quality work. In my research, it appears Demello is a similar demographic and provides quality workmanship, as well. Both companies provide quality cranks on par, if not, better than Chinese cranks, at a competitive price.
I personally don't know why people choose Chinese parts over German and not give their money to local businesses. Granted, you do when buying from a U.S. parts distributor. But that's about the extent of it. Do as you will. It's a free country. If anyone is asks why small VW shops close their doors in the future, this will be one reason why. |
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slayer61 Samba Member
Joined: June 01, 2021 Posts: 1018 Location: CA
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Posted: Mon Sep 20, 2021 1:08 pm Post subject: Re: Crank snapped in two. Oil starvation or crank flaw? |
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Shane Tuttle wrote: |
Quote: |
I don’t know why anyone would use a 30-50 year old crank these days when you can buy new ones. |
The alternative, for the most part, is a crank sourced from China. Their cranks have history or breaking as well. And they're not 30-50 years old.
If I can reasonably and economically do it, I won't buy anything sourced from China.
DPR uses original German forged cranks. Arguably, it's a better material to use. Jose is a small business that provides high quality work. In my research, it appears Demello is a similar demographic and provides quality workmanship, as well. Both companies provide quality cranks on par, if not, better than Chinese cranks, at a competitive price.
I personally don't know why people choose Chinese parts over German and not give their money to local businesses. Granted, you do when buying from a U.S. parts distributor. But that's about the extent of it. Do as you will. It's a free country. If anyone is asks why small VW shops close their doors in the future, this will be one reason why. |
Well said |
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SLAKKER Samba Member
Joined: August 11, 2010 Posts: 56 Location: SOUTH AFRICA
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Posted: Mon Sep 20, 2021 2:03 pm Post subject: Re: Crank snapped in two. Oil starvation or crank flaw? |
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Either Metal Fatigue or the radius journal was not ground
to spec |
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RickS Samba Member
Joined: May 05, 2005 Posts: 430 Location: Speonk, NY
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Posted: Mon Sep 20, 2021 4:31 pm Post subject: Re: Crank snapped in two. Oil starvation or crank flaw? |
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Shane Tuttle wrote: |
Quote: |
I don’t know why anyone would use a 30-50 year old crank these days when you can buy new ones. |
In my research, it appears Demello is a similar demographic and provides quality workmanship, as well. |
Is Demello around any longer? I thought they have been out of business for a long while. |
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mikedjames Samba Member
Joined: July 02, 2012 Posts: 2742 Location: Hamble, Hampshire, UK
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Posted: Tue Sep 21, 2021 10:49 am Post subject: Re: Crank snapped in two. Oil starvation or crank flaw? |
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Maybe, hard to tell from the pictures:
One end of the break on the surface of the crank seems pretty close to the end of one of the welded seams for the added counterweight.
Maybe the welding left some stress in the metal. _________________ Ancient vehicles and vessels
1974 VW T2 : Devon Eurovette camper with 1641 DP T1 engine, Progressive carb, full flow oil cooler, EDIS crank timed ignition.
Engine 1: 40k miles (rocker shaft clip fell off), Engine 2: 30k miles (rebuild, dropped valve). Engine 3: a JK Preservation Parts "new" engine, aluminium case: 26k miles: new top end.
Gearbox rebuild 2021 by Bears.
1979 Westerly GK24 24 foot racer/cruiser yacht Forethought of Gosport.
1973 wooden Pacer sailing dinghy |
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risk Samba Member
Joined: June 24, 2004 Posts: 710 Location: Stumpbroke, Arkansas
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Posted: Tue Sep 21, 2021 11:24 am Post subject: Re: Crank snapped in two. Oil starvation or crank flaw? |
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SLAKKER wrote: |
Either Metal Fatigue or the radius journal was not ground
to spec |
Definitely fatigue. The beach marks tell the tale.
Here is a 82 Okrasa I broke. Survived many years of racing in a USAC midget car.. then I put it in a sedan with a turbo. That was the final nail in the coffin!
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Ohio Tom Samba Member
Joined: February 09, 2006 Posts: 1660 Location: Marshallville Ohio
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Posted: Tue Sep 21, 2021 1:39 pm Post subject: Re: Crank snapped in two. Oil starvation or crank flaw? |
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[quote="Clatter"]This happens a lot, actually.
Just like yours, right next to the center main.
Aftermarket, factory, counterwieght, stock, stroker, doesn't matter.
When your number comes up, it comes up.
It's not something you did wrong or anything else.
It just happens.
Hopefully your line-bore is still good..[/quote
Spot on..
Looks like the crack started from the journal radius, just like they always do.
This is the risk you take when having a high-milage crank as the base for a welded C/W crank.
I know they get inspected before chosen for the job, but it's still a Used part they start with.
However, it can happen to any crank and often does.
Even stock motor broke crankshafts... |
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Shane Tuttle Samba Member
Joined: February 02, 2011 Posts: 173 Location: Arlee, Montana
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Posted: Tue Sep 21, 2021 3:19 pm Post subject: Re: Crank snapped in two. Oil starvation or crank flaw? |
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RickS wrote: |
Shane Tuttle wrote: |
Quote: |
I don’t know why anyone would use a 30-50 year old crank these days when you can buy new ones. |
In my research, it appears Demello is a similar demographic and provides quality workmanship, as well. |
Is Demello around any longer? I thought they have been out of business for a long while. |
I have no clue, now. When I try their website, it goes to some Japanese domain. |
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txoval Samba Member
Joined: January 23, 2004 Posts: 3552 Location: The Woodlands, TX
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Posted: Tue Sep 21, 2021 3:23 pm Post subject: Re: Crank snapped in two. Oil starvation or crank flaw? |
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Demello is no longer around |
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71ghiavert Samba Member
Joined: February 21, 2017 Posts: 98 Location: Mill Valley, Ca.
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Posted: Wed Sep 22, 2021 10:45 am Post subject: Re: Crank snapped in two. Oil starvation or crank flaw? |
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This was an American-built, high-quality crank on a German core. Highly recommended even here on Samba. "Stuff," as Shakespeare so wisely said, "happens. You know?"
Trying AA next time and hoping for a different outcome. |
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txoval Samba Member
Joined: January 23, 2004 Posts: 3552 Location: The Woodlands, TX
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Posted: Wed Sep 22, 2021 2:25 pm Post subject: Re: Crank snapped in two. Oil starvation or crank flaw? |
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Spend a little more and buy a Scat 4340 crank...last one you’ll buy
Would have to move to a 78.8mm crank though |
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71ghiavert Samba Member
Joined: February 21, 2017 Posts: 98 Location: Mill Valley, Ca.
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Posted: Wed Sep 22, 2021 8:41 pm Post subject: Re: Crank snapped in two. Oil starvation or crank flaw? |
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I'd buy the Scat if they made a 74mm, but I don't think they do. If I move up to a 78.8, then I think I'd need new pistons to go with my 5.35 rods, and might get into problems and a lot of extra work dialing in deck height and compression (heads were chambered for 9:1 with the set-up I have).
With the same size replacement crank, I'm likely to be very close as is. I hope to keep the fix simple--new crank, new bearings everywhere, new rings--and get back on the road as quickly as possible. The engine felt really good before it blew up!! |
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oprn Samba Member
Joined: November 13, 2016 Posts: 12730 Location: Western Canada
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Posted: Thu Sep 23, 2021 3:04 am Post subject: Re: Crank snapped in two. Oil starvation or crank flaw? |
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I bought an AA one in stock stroke. It cam unbalanced and at first my balancer/machinist refused to balance it. "Too far out" he said. He wanted me to return it but the guy I bought it from refused to take it back saying the next one won't be any different. I put them in touch with each other to fight it out. In the end the balancer used what he called "unconventional means" to balance it.
I posted a thread about it here and didn't get any comments really so I went ahead and used it. There is only about 4 hours running on it at the moment and it seems fine... _________________ We had the stone age, the bronze age, the industrial age and now we are in the age of mass deception and mind control for corporate profit. (The mass media age) |
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txoval Samba Member
Joined: January 23, 2004 Posts: 3552 Location: The Woodlands, TX
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Posted: Thu Sep 23, 2021 4:05 am Post subject: Re: Crank snapped in two. Oil starvation or crank flaw? |
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Scat makes a 74mm crank in their Billet versions, but those are $1800
I hear you on keeping the fix simple. If you change your mind, get the 78 crank and buy B pistons...can still reuse your cylinders. No need for forged pistons |
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Pruneman99 Samba Member
Joined: February 22, 2012 Posts: 5013 Location: Oceanside
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Posted: Thu Sep 23, 2021 6:57 am Post subject: Re: Crank snapped in two. Oil starvation or crank flaw? |
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I got a 76mm 4340 EMPI and it was near perfect for balance out of the box. Actually the worst part was the OG flywheel I had them drill for 8 dowel. The 9 spring OG pressure plate needed a little bit.
Idk how the 74mm ones are. |
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bugguy1967 Samba Member
Joined: January 16, 2008 Posts: 4341 Location: Los Angeles, CA 90016
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Posted: Thu Sep 23, 2021 10:12 am Post subject: Re: Crank snapped in two. Oil starvation or crank flaw? |
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71ghiavert wrote: |
I'd buy the Scat if they made a 74mm, but I don't think they do. If I move up to a 78.8, then I think I'd need new pistons to go with my 5.35 rods, and might get into problems and a lot of extra work dialing in deck height and compression (heads were chambered for 9:1 with the set-up I have).
With the same size replacement crank, I'm likely to be very close as is. I hope to keep the fix simple--new crank, new bearings everywhere, new rings--and get back on the road as quickly as possible. The engine felt really good before it blew up!! |
Scat has a Volksaver 74 and a billet _________________ "A petrol engine can start readily, run smoothly and give every appearance of being in good order, without necessarily being in good tune." - Colin Campbell, "The Sportscar Engine" |
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evanfrucht Samba Member
Joined: July 24, 2016 Posts: 2180 Location: Laurel Canyon, CA
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Posted: Thu Sep 23, 2021 10:31 am Post subject: Re: Crank snapped in two. Oil starvation or crank flaw? |
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Empi 4340 or Scat. I think they are both the same stuff, same factory. Both have a good track record. Empi is usually cheaper. Car Craft has the best deal online.
Sounds like you just go unlucky. Forging varies each time, sometimes the grain pattern/metal structure just doesn't quite end up the way it's supposed to. Perhaps the drilling weakend it (drilled to close to journal in error) Maybe the welder screwed up or the heat messed something up. Who knows why it happened. _________________ 1967 Bug ( the daily rod )
1964 Fury Wagon ( the pavement shredder )
Last edited by evanfrucht on Thu Sep 23, 2021 10:36 am; edited 1 time in total |
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