Broken Crankshaft Count?

[S Phinney]

How could it be unless it was already cracked

 

[mike diesel]

How could it be unless it was already cracked

My thoughts exactly.

 

[Ne-max]

How could it be unless it was already cracked

Do you think it gets weaker and weaker before it cracks or do they just up and crack? I personally would think that having so much stress up to that point will still leave a weak spot in it. But I might be thinking to much

 

[zf>allison]

My thoughts exactly.

I my thoughts were a new crank would be better as the old one could be "fatuiged" obviously with no proof or way to back that up. I don't know if it would matter or not

 

[S Phinney]

It really depends on the material traits. Some weekend until failure and some just fail. Take 4032 and 2618 aluminum used in pistons. 2618 will take more abuse. While 4032 initially appears better but suddenly fails without any signs of failing.

 

[countrycorey]

Do you think it gets weaker and weaker before it cracks or do they just up and crack? I personally would think that having so much stress up to that point will still leave a weak spot in it. But I might be thinking to much

Yes, it gets weaker due to fatigue


Corey

 

[zf>allison]

Do you think it gets weaker and weaker before it cracks or do they just up and crack? I personally would think that having so much stress up to that point will still leave a weak spot in it. But I might be thinking to much

My thoughts were it would fatigue that's why some brake as there cruising down the road. Not at a max load situation.

 

[Dave c]

If you're going to pretend to not be someone else, at least have someone else structure your sentences.

What are you talking about? I posted to answer a simple logical explaination about timing swing variations.

 

[Dave c]

I too have heard of alter fire crank failures. It does seem to be much less often than standard fire. However I know the alter fire spools slower and makes less power with a direct swap.

 

[LBZ]

How could it be unless it was already cracked

My thoughts exactly.

Already being harmonically cycled, shock loaded, etc. "X" amount of times with the standard FO which would stress and add fatigue to it would be my guess as it maybe being factor.

And those that didn't properly check or maybe didn't check it all may miss cracks just starting. Brian found a crank like this-good thing he had it properly checked.

For best results, I would suggest starting new myself.

 

[Ne-max]

Already being harmonically cycled, shock loaded, etc. "X" amount of times with the standard FO which would stress and add fatigue to it would be my guess as it maybe being factor.

And those that didn't properly check or maybe didn't check it all may miss cracks just starting. Brian found a crank like this-good thing he had it properly checked.

For best results, I would suggest starting new myself.

This is the reason I am putting a new LB7 in my build.

 

[LBZ]

I too have heard of alter fire crank failures. It does seem to be much less often than standard fire. However I know the alter fire spools slower and makes less power with a direct swap.

Another "I heard of" story.

Got any proof Wade?

 

[LBZ]

This is the reason I am putting a new LB7 in my build.

And why I swung for the fences and went LML!

 

[hondarider552]

I bought a new lb7 crank last Monday for the new build.

 

[Ne-max]

And why I swung for the fences and went LML!

I looked into a LML. But already had a LB7 dampener and flexplate to use on it. Could now find any info on what style a guy needed for a LML crank.

 

[LBZ]

I looked into a LML. But already had a LB7 dampener and flexplate to use on it. Could now find any info on what style a guy needed for a LML crank.

From what I understand LBZ up will work. I'll find out soon enough. JD Dave did it with LMM stuff IIRC.

 

[duramaximizer]

Alt fire cam spools slower? More top end?

 

[PACougar]

Alt fire cam spools slower? More top end?

Don't bother asking, he won't post evidence.

 

[56taskforce]

Another "I heard of" story.

Got any proof Wade?

Don't bother asking, he won't post evidence.

Of course, it's his neighbors, cousins, sisters friend's second cousin. Everyone knows about thar one. :roflmao:

 

[56taskforce]

So if you take all 8 cylinders and have a single combustion event in each, or in other words a full cycle, does the timing vary a total of 8 degrees if comparing 2 cylinders? If that is true and then you combine the info on non equal cylinder charge according to Banks, would this be a good indicator of why the cranks, regardless of either stock or billet aftermarket break in the same place more often than not? Just trying to wrap my head around this.

It is a four cycle meaning each cylinder fires every 720° of rotation devided by 8 cylinders that is 90° between power cycles.