cutting the crankshaft?

[Race94]

People "cut" crankshafts to certain degrees , what does this mean?

 

[kooka]

you mean to "knife" the crank?

 

[steve]

Usually that means putting the crank in a lathe and turning the main and rod journals to make them round and smooth again. Your cutting metal off the crank.

Some DSM cranks have a nitrated surface hardening treatment and turning them will remove the hardening.

Steve

 

[Defiant]

People "cut" crankshafts to certain degrees , what does this mean?

I give up, what does it mean?

Are you hanging around with V-8 racers or something? Cranks are polished, and if truly serious, ground. Which I think Mits says to not do with a crank of theirs.

In other realms of engine practice, the rod throws can be machined off their normal centers in order to change stroke length.

 

[NDgsx]

Some DSM cranks have a nitrated surface hardening treatment and turning them will remove the hardening.

Some? Every six bolt does and that's all that matters. If you're rebuilding 7 bolts, well uh good luck

 

[NosLaser]

They typically 'cut' crankshafts when they have small score marks in them that are too deep to remove with a simple polishing, and like Steve said, if the journals are out of round they will cut them to get a perfect surface. Whenever you cut the crankshaft, you will need oversize bearings as well. The terminology is going to be for example 'the crank is cut .010" under, and will require .010" over bearings."

Regards,

 

[steve]

I didn't feel like double checking so I went with a marketing answer

Steve

 

[Cesar]

So we shouldn't cut our cranks...
My machinist said mine needed cutting...
I should find another?? 6 bolt.
Thanks

 

[kooka]

I should find another??

did you skip over post #3 and #5?

 

[Cesar]

did you skip over post #3 and #5?

Yes I did.
If your not going to give me sound ADVICE please do not post.
Thanks

 

[NosLaser]

Yes I did.
If your not going to give me sound ADVICE please do not post.
Thanks

He was redirecting you to sound advice, but what it appears is you want to be hand-held instead of thinking for yourself.

The cranks have a nitride coating from the factory which serves to harden them. In higher horsepower applications, this can help the crank journals withstand being oblonged or scored when crankshaft deflection starts to become a factor. For a street car that will not see much racing use, a cut crank will be fine. If you are looking to make a lot of power, or rev to higher rpm, you may want to go with an uncut crank that you can just have micropolished.

If that wasn't the Sound Advice you were looking for, then you can ignore it and just click here.

Regards,

 

[Cesar]

He was redirecting you to sound advice, but what it appears is you want to be hand-held instead of thinking for yourself.

The cranks have a nitride coating from the factory which serves to harden them. In higher horsepower applications, this can help the crank journals withstand being oblonged or scored when crankshaft deflection starts to become a factor. For a street car that will not see much racing use, a cut crank will be fine. If you are looking to make a lot of power, or rev to higher rpm, you may want to go with an uncut crank that you can just have micropolished.

If that wasn't the Sound Advice you were looking for, then you can ignore it and just click here.

Regards,

A simple "yes I think that that would be a good idea, speacially if your running a lot of power." would do just fine.

No I don't need you to hold my hand nor do I need your smart ass remarks WISEMEN.

Thanks for the info anyway, next time I'll look elsewhere, hopefully I won't run into the same ignorance.

Sometimes people need to be reassured, that's all.

 

[NosLaser]

A simple "yes I think that that would be a good idea, speacially if your running a lot of power." would do just fine.

No I don't need you to hold my hand nor do I need your smart ass remarks WISEMEN.

Thanks for the info anyway, next time I'll look elsewhere, hopefully I won't run into the same ignorance.

He pointed out a post that would have answered your question, but instead of listening, you decided to make a smart ass "thanks, but if anyone has any REAL advice" comment. YOU are in the wrong here.

Please do look elsewhere, because not many people tolerate someone who refuses to take ANY initiative whatsoever and just wants to be spoonfed every single bit of information. I also hope that you don't subject the rest of us to any more of your ignorance either.

Regards,

 

[Cesar]

1. I did read the entire thread. Nobody mentioned anything about NOT running cut cranks until I posted something.

2. redirecting me to a post which I already read, does not help me, and is not Advice.
Specially considereing the person redirecting me initialy thought we were talking about "knife edging".

3. Apparently you know me really well, and your absolutely right, I never take any initiative.

4. I'm wrong? what did I do? Ask a simple question and simply receive a responce with attitude?

Spoon fed? Held-hand? What 's next? any more put downs?

 

[NosLaser]

According to your OWN words, you did NOT read the whole thread.

did you skip over post #3 and #5?

And your response:

Yes I did.
If your not going to give me sound ADVICE please do not post.

That post stated the coating on the cranks, which would lead one to understand that cutting the hard coating off, would weaken the surface of the crank. That DID answer your question. Either you didn't read it (like you said you didn't) or you are refusing to acknowledge it and are just being difficult to get a rise out of people. If you DID in fact read it, and responded wrong by saying you skipped over it, then you still made a mistake.

Spoonfed? Held-hand? What 's next? any more put downs?

Jesus f*cking Christ on a popsicle stick in November!!!! Telling someone they are asking to be spoonfed is a f*cking put down now too??????? What the f*ck is next? Internet law suits for 'hurt feelings?' WTF is this world coming to??!!!!?? Is EVERYTHING offensive?

Regards,

 

[Cesar]

I did make a mistake. I answered yes to skipping the posts when I didn't skip them. I thought he had asked me if I had read them.

I'm not trying to get a rise at people. you may think that that is what i'm trying to do but I feel the same way about you.

I did not get the jesus on a popsicle stick remark, and no not everything is offensive, some poeple have no manners...

 

[kooka]

Ok, enough.

Caesar: Huck the crank, hang it on the wall in the garage, or sell it on ebay. You want a new (well, new to you) one.

Goodluck.

 

[al5dsm]

Some? Every six bolt does and that's all that matters. If you're rebuilding 7 bolts, well uh good luck

Exactly what happened to me.. 112 miles later = spun rod bearing

 

[heavyD]

Exactly what happened to me.. 112 miles later = spun rod bearing

If you spin a rod bearing 112 miles after a rebuild to any engine it is because the engine wasn't put together properly or the wrong parts were used.

 

[Maglin]

If you spin a rod bearing 112 miles after a rebuild to any engine it is because the engine wasn't put together properly or the wrong parts were used.

Usually a spun Rod bearing is caused when the big end of the rod is out of round. When you rebuild an engine you MUST have the rods checked and usually you will have one or two rods that need resizing. I know as one of my first builds when I was 16 was on a motor that spun a rod bearing and my machinest was like "did you spin a bearing?" and I said yeah why? "Cause it will just happen again if you don't fix it."

 

[kooka]

the wrong parts were used.

thats what he implied.

 

[bigjangin]

Exactly what happened to me.. 112 miles later = spun rod bearing

having a turned crank wont make you spin a rod bearing. If you use the right bearings the car should be fine. You dont turn a 6 bolt crank as it has been said because it cuts into the outer hardening layer, which will lead to broken cranks, not spun rod bearings.

 

[pinknuggit]

This thred is so misleading it's not even funny. You do not need to chunk a crank if it needs to be turned (a.k.a, knife edged, cut, whatever you want to call it). You can run it as long as you have oversized bearings. We turned a crank .020" over for a guy here at work who also has a dsm. He put 322whp down on a 20G and has been running the same setup for over a year now.

Saying that someone needs to find a new crank because their needs to be turned is BAD ADVICE. Yeah sure, the stock ones are nitrided, but just because you take that off doesn't mean the crank is junk. Odds are, very few people on here are running enough power to have a need for nitrided journals. There Are plenty of machine shops around the country that can Re-Nitride the journals.
A crank that has been turned has a higher chance of breaking in half vs. one that hasn't, but that chance isn't enough to even make a difference unless you're running ungodly amounts of power. Hell, you have more of a chance of bending a connecting rod than breaking a crankshaft which has been turned.


And i don't know about everyone else, but i'm on ceasar's side. I could not see a clear answer to his question.



He asked: "I should find another?? 6 bolt.
"

Post #3 answered :"Usually that means putting the crank in a lathe and turning the main and rod journals to make them round and smooth again. Your cutting metal off the crank.

Some DSM cranks have a nitrated surface hardening treatment and turning them will remove the hardening.



Post #5 answered :"
Some? Every six bolt does and that's all that matters. If you're rebuilding 7 bolts, well uh good luck



Now is it just me, or do i NOT find a SPECIFIC ANSWER in the replies?!?!?! He asked a question which needed a YES/NO answer. I don't see ANY relevance to his question in those replies. Simply implying that "a turned crank weakens the surface" is Not a very good answer to "should i get another one?" Remember, people on here can Not read minds.
People should also refrain from posting unless they have personal experience with the topic matter. It's obvious that the people who say a turned crank is bad do not have experience with running a turned crank in their motor.

 

[Cesar]

pinknuggit I apreciate the feedback.

To stay on topic the machinist doing my block and crank told me the same thing. He said that he would radius grind the crank to .010". When I spoke to him about the removal of the nitride, he told me not to worry. I'm pretty anal about this sort of thing, so I'm still in the search for a standard crank. Nevertheless I still think (much like pinknuggit mentioned) that running a cut crank won't hurt. I still haven't seen the power limits of a standard crank vs. a cut (unnitrated) crank. If anyone has info based on first hand experience or a link to some info, please post. I'm pretty curious.

Canadian Pricing:
crank polishing-50$
turning the crank (cutting)-150$ (includes polishing)
nitrating- 200$


Thanks

 

[pinknuggit]

The crank in my last 4g6 was ground .010" over and it did Just Fine.