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Broken crankshaft

Jackson1320

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I've no idea how to prove to a random on the internet anything...let alone my mechanical skills.
You don’t owe anyone anything but just knowing that someone can back up what they said changes how you are viewed. The picture is good enough for me. I’m not asking for a degree as proof
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Cory S

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They certainly weren't strong cranks on the old 302s, but typically only broke with the cog setups. Had to do with belt slip being a necessary at certain times.
Yep. Cogged belts don't side load the snout, but they also don't slip at ALL during load/unload high twist situations. Radial shearing is the outcome.

This almost leans me to believe my theory that crank snout shearing is caused from twisting torque, and not from lateral pull on the snout... In that case, the "crank support" may not help at all. Loading/unloading the front of the snout with RPM and the added forward weight of the drive pulley trying to twist back and forth is 99% of the cause.

YET... If there is some lateral flexing that is causing failures, then I can see where the crank support can keep flexing at bay and potentially reduce failure. Has there been any noted failures WITH these crank snout supports?



Any others thinking the same?
 
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WildHorse

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Any others thinking the same?
Id like to see aftermarket balancer vs stock balancer crank failures. Or for that matter 2step vs just holding the brake. Also would be nice to see if the break was radial or linear.
 

SolarFlare

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Honestly, I don’t think about it. Looking back, if I did, I’d have wasted a whole lot of time thinking about something that hasn’t happened. Hell I might have psyched myself out of many track outings.
 

bankyf

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Something I found in an unrelated Google search search the other day. It had initially been shared from another group (maybe even this one) but I felt it was somewhat relevant to the discussion.


"The following excerpt is from personal email exchanges from April, 2016. It is posted with permission courtesy Mike Robins, Supervisor, Ford Performance:

:ford:>
This is coming from our engineering team and also the party that inspects every engine we look at that has experienced issues.

Uncontrolled torsional vibrations break the oil pumps.
It is not the oil pump gear material or the heavier oil that breaks the pump.

The large mass of the flywheel /pressure plate or flywheel / torque converter control the torsional vibrations at the rear of the crankshaft. The vibration damper controls them at the front of the engine.

The production vibration damper is designed to work within the production vehicles RPM limit and power level.
At 8000 rpm you are past that limit.

Changing engine internal components and or installing power adders can change damper requirements.
Just installing an aftermarket race damper is not always a fix.
Some aftermarket dampers are not tuned correctly and do not control the torsional vibrations.

Why do Ford Performance and other companies sell oil pumps with steel gears?
The steel gears will survive longer in the harsh conditions of uncontrolled torsional vibrations.
Some of the other components that are subjected to the damaging torsional vibrations are the timing gears and chains.

People that blame the oil pump gears or the timing chain gears and chains as being substandard do not understand the damaging effect of uncontrolled torsional vibrations.

Regarding your ATI damper question, the ATIs seem to be fine, we use them in the Cobra Jets. We've seen issues with other brands I won't name. You can certainly pass the info along! There's no objection on my part as long as the context is fitting, you may even want to paraphrase, etc.

Thanks again!

Best regards,

Mike Robins
Supervisor-Info Center
Ford Performance
"
 

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Robottrainer

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1900 ish. Going to have my shop order it so hopefully cheaper
Why not get just the block and order better pistons, rods and crank and never look back? For that matter your block is probably OK. You have the engine out anyways, it isnt that much further to go to build a stout piece. Just my 2 cents.
 

illtal

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Why not get just the block and order better pistons, rods and crank and never look back? For that matter your block is probably OK. You have the engine out anyways, it isnt that much further to go to build a stout piece. Just my 2 cents.
this has been over TGGT sold his mustang too
 

DougS550

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Why not get just the block and order better pistons, rods and crank and never look back? For that matter your block is probably OK. You have the engine out anyways, it isnt that much further to go to build a stout piece. Just my 2 cents.
For me, I agree sound advice. If and when my engine comes out without a second thought, Pistons, Rods, Titanium valves, springs, sleeves, Cams, maybe "O" Ring heads, Cryo all moving parts, balance blue print Crank, Rods, Pistons, beef up transmission, Done. It is basically a race engine and not a Lexus so I expect to treat mine as such. I wish him good Luck
 

80FoxCoupe

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For me, I agree sound advice. If and when my engine comes out without a second thought, Pistons, Rods, Titanium valves, springs, sleeves, Cams, maybe "O" Ring heads, Cryo all moving parts, balance blue print Crank, Rods, Pistons, beef up transmission, Done. It is basically a race engine and not a Lexus so I expect to treat mine as such. I wish him good Luck
He put a stock engine back in and sold the car.
 
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TGGT

TGGT

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this has been over TGGT sold his mustang too
This is true. Haven’t had the car in about 6 months. The stock gen3 engine was plenty strong for what I was doing. It was just a crank snout issue. I firmly believe that with the crank support this is a non issue
 

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DougS550

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He put a stock engine back in and sold the car.
If I was selling the car, absolutely I would slap a used engine or rebuild the original one back to spec and sell. Sorry for the Mix-up.
 
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TGGT

TGGT

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Actually, I bought a stock gen3 long block. Put oil pump gears in it, an ati balancer, procharger crank support, and put the blower back on and drove it for three months before returning it to stock and selling it. I now have an 11 gt 6 speed with some minor bolt ons which is enough to keep me entertained for the moment and a 21 Silverado
 

Jackson1320

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For me, I agree sound advice. If and when my engine comes out without a second thought, Pistons, Rods, Titanium valves, springs, sleeves, Cams, maybe "O" Ring heads, Cryo all moving parts, balance blue print Crank, Rods, Pistons, beef up transmission, Done. It is basically a race engine and not a Lexus so I expect to treat mine as such. I wish him good Luck
$30,000 later
 
 




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