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Hard-core CEG'er
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Originally posted by Mark:
Yes, I have heard crank flex at speed can do damage to bearings as well, although I would expect to see some broken cranks along with the spun bearings. HAve guys been reporting broken cranks? I would be curious what the majority of the failure modes have been over the years. Has this info been discussed at all?
The stock crank is a very stout forged unit; breaking it is very unlikely. The bearing has a hard tin core. The hard bearing can not get out of the way (so to speak) of the whipping crank. The higher the rpms the worse the whip! Majority of engine failures are oil related. Normally loss of oil pressure due to bearing failure. (Which of course crank whip would precipitate) Yes. 
2000 SVT #674
13.47 @ 102 - All Motor!
It was not broke; Yet I fixed it anyway.
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Forged? Hmmmm I take it just for the SVT engine? Thought Honda was one of the few that used forged vs. cast?
Tnx
Paul
Paul
98 Mystique LS 2ea (07/97)(08/98)
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Joined: Sep 2000
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Hard-core CEG'er
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Hard-core CEG'er
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Originally posted by F111D F:
Forged? Hmmmm I take it just for the SVT engine? Thought Honda was one of the few that used forged vs. cast?
Tnx
Paul
Every Duratec made (2.5L or 3L) uses the same forged billet steel & counterweighted crankshaft. SVT's just have the creme of the crop (hand selected) so to speak. It's one tough piece of work!
2000 SVT #674
13.47 @ 102 - All Motor!
It was not broke; Yet I fixed it anyway.
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Joined: Aug 2001
Posts: 46
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New CEG\'er
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Why does the crank whip so bad if the unit is a strong forging? 
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Strong doesn't equal rigid. Think of the crank as a very strong spring (or torsion rod if you prefer). Every time a cylinder fires, it winds the spring up a little. Then the spring unwinds a little. The twist in the spring causes the journals to angle a little bit, closing the gap (formed by the oil film) between them and the bearings. Bearings and journal touch, get hot, Babbit (bearing material) gets hot, melts, bearing friction increases, bearing spins, engine knocks, oops, new bearing and crank time.
My name is Richard. I was a Contouraholic.
NOW: '02 Mazda B3000 Dual Sport, Black
BEFORE: '99 Contour SE Sport
Duratec ATX Spruce Green
PIAA 510's, Foglight MOD, K&N Drop-in
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Joined: Aug 2001
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Wow thats a pretty neat example! lets see if I understand you. The crank distorts like a spring and this causes one of the journals to cocksideways and this is what is causing the bearing to fail? Do you know if anybody has any pictures of the spun bearings after they removed them? This is interesting, I sure would like to see those bearings. 
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It's not an uncommon problem. Long crankshafts had it years ago. that's why V engines are "better" than straight. A straight 12 cylinder engine was really long, a BIG spring.
More bearing help, but as all springs have a natural frequency and harmonics, even short shaft can run into problems.
My name is Richard. I was a Contouraholic.
NOW: '02 Mazda B3000 Dual Sport, Black
BEFORE: '99 Contour SE Sport
Duratec ATX Spruce Green
PIAA 510's, Foglight MOD, K&N Drop-in
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CEG\'er
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If I remember correctly, cast cranks suffer less from crank whip due to the even grain of the casting. But, you need forged material in high rpm applications, that is why a forged crankshaft is perfered in high rpm applications. In any case, you always use a harmonic balance to damper vibration and a dual mode damper dampens on two frequencies.
Just a thought, has anyone ever emailed the fluidamper company and requested they supply a balancer for our cars?
stock 1998 silver frost SVT E0 #1545 out of 6535
* K&N drop-in air filter
* DMD
* Koni's w/ stock springs
* Autolite double platinum
* Tranny cocktail
* Mobil 1 Snyth Oil @ 60K miles
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What could one expect to pay for the repair of a spun bearing??? Labor/Parts??????
1998.5 CSVT #3617
K&N Custom Intake
Custom 2 3/4 Magnaflow cat back
Ram HD Power Grip Clutch
Energy Suspension Inserts
Bosch Platnium +
Bf-Goodrich G-force radials "KDWS"
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Boston mids
More to come: Stock Sucks!!!!
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Originally posted by holycowSVTpaul:
In any case, you always use a harmonic balance to damper vibration and a dual mode damper dampens on two frequencies.
Not true. A harmonic balancer is used on engines that are not internally balanced. The Duratec is. (as are most other engines) It uses a crank pulley with an integral damper and does not have a harmonic balancer. Like you stated, the DMD is a damper that has two rings to dampen harmonics in 2 different frequency ranges.
2000 SVT #674
13.47 @ 102 - All Motor!
It was not broke; Yet I fixed it anyway.
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