Another myth put out to pasture
 

I am in the process of building a 258" engine for my "t" tub. I had two crankshafts that had been stored on the floor on their sides wrapped in plastic for at least 20 years. I took them both to the machine shop to be checked and have the best one prepped to use. It turned out that the were both good, so we decided to use the one that looked the best, which cleaned up at .010-.020. Knowing that there is some controversy about storing crankshafts, I asked the machinist to check them both for run-out. He said both were less than .003, and in any event, turning them .010 or more would render even that small amount of no consequence.

Re: Another myth put out to pasture
 

Good to know.

Re: Another myth put out to pasture
 

How does this put the myth to rest? If properly stored they should have no run out. I wouldn't be happy checking for run out on a shaft of any type and finding .003.

Re: Another myth put out to pasture
 

Yep, a sample of two cranks proves that the myth has now been put to rest forever. This 'test "makes me so happy to know you do not work for a pharmaceutical company. I can hear it now "yep, we tested those pills on two people and neither one died. We're good to go!"

Re: Another myth put out to pasture
 

Very good point indeed! Your perspective is apparently one from an educated background in metals and / or metal working.

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Fine. Feel free to scrap all of your crankshafts with less than .003 run-out. Not me.

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Hey Tub it didn't take long did it!!

R

Re: Another myth put out to pasture
 

Yeah, that was quick. I wonder if I should set up one of those threads with a poll on whether I should put this build on indefinite hold!

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Yes and our machine shop stored shafts to be ground even for short periods either hung up vertically or supported horizontially. Someone besides me thought this was important enough as some of the storage racks were from the 20's and 30's.

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So if this myth were to be true, then when hanging a crank by the front counterweight the crank is going to stretch, what with 80% or more the of crank's weight suspended off-center (2 inches off-center in the case of a Merc crank)!

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You don't think that maybe hanging cranks vertically is just the best way to utilize storage space?

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So if you store it on end without hanging, will it compress over time?

Re: Another myth put out to pasture
 

If you hang them for a long enough time, you can use them in V-12s...

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The myth says yes!

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It will tip over and hit your toes....i know !!!
Trying to zigzag your way to the crankgrinder.....sooner or later they will get you ;)

Re: Another myth put out to pasture
 

There are now two posters that understand metals and metal working.
Bill

Re: Another myth put out to pasture
 

No machine shop i have called on hangs a crankshaft by the counterweight!!

R

Re: Another myth put out to pasture
 

But nobody knows how much runout they had when put into storage 20 years ago. Was it 0.000, 0.003, 0.006? Without knowing that it isn't possible to say anything about this "experiment".

Re: Another myth put out to pasture
 

Hi all; I had 3 merc cranks verticaly stored by leaning against the wall in '96. I was outside my shop going to work ,at about 5:30 am, and our 'spring break quake' hit, a 5.6 er. My shop sounded like a Sunday church call to services! Ding-dong-ding, One crank is cracked BAD, and I never checked the other two. You can't always win.. Newc

Re: Another myth put out to pasture
 

Even if you hang it from the center bolt, the load of the crank's weight is still 2 inches off-center (in the example of a Merc crank). So if the myth is correct, you will still end up with a distorted crank!

Re: Another myth put out to pasture
 

Everything will have some amount of run-out to one degree or another. It is next to impossible to machine any turned shaft, whether it be a crankshaft or not, with absolutely zero run-out.

The real question is: What amount of run-out is acceptable for a Flathead crankshaft?

Lots of speculation on this subject by folk (both here and elsewhere) that have little to no background in mechanics of materials and are instead solely relying on hearsay.

Re: Another myth put out to pasture
 

OK. I have been looking all over the internet trying to find what the acceptable run-out should be for a flathead crankshaft. Very surprisingly, there seems to be no information on this. Just about everything I looked at said that proper bearing clearances are much more important than run-out. The one place I did find some actual numbers were on snowmobile forums. This is typical of what I found :

"I have heard between 2.5-3 thousands are factory spec so the question is how far does one let the crank get out of spec before repair? 4-5-6? What is a good measure to tell when the crank is on its last legs or could benefit from some preventative maintenance."

I have owned a few snowmobiles, and all of them had a red-line of over 10,000 RPM. From this, I have to believe that "less than .003" would be more than adequate for a flathead. Therefore, I stand by my initial statements.

I have spent some time and money determining these facts, which I believe will benefit the majority of members here.

I hate to have to say this, but unless you guys can come up with some solid, verifiable numbers, "37 Coupe" and "Kube": stay out of this thread; you have nothing to add but negativity, and that hurts everyone.

Re: Another myth put out to pasture
 

you guy's crack me up.

Re: Another myth put out to pasture
 

Run out, I'm lucky if I can crawl out some mornings, yikes
Charlie ny

Re: Another myth put out to pasture
 

Thinking more about this alleged run-out issue: So we have a crank laying horizontally on a shelf for years. Since it is supported in several places by the counterweights no matter how you turn it, just where does this distortion occur? At the front main? Center main? Rear? At one of the crank throws?

Re: Another myth put out to pasture
 

Why don't y'all just keep your crankshafts in your engines like I do? Haven't had mine sag in there. :rolleyes:

Re: Another myth put out to pasture
 

Are you saying that only posters that agree with you can post on your thread?
Bill

Re: Another myth put out to pasture
 

Not at all. Read my post again; If they have any proven, verifiable hard information, they are very welcome to post. We don't need any unverified opinions or off the wall theories. I spent a bunch of time and money determining what I did; I only ask that they do the same.

Re: Another myth put out to pasture
 

In science it's very hard (maybe impossible) to prove a negative.
Having an example of something not happening only shows that it sometimes doesn't happen.
Having an example of something happening shows that it sometimes does happen.

Does anyone have an example of a crankshaft that was known to be perfectly straight (or of a known amount of runout and just where the runout was), and then stored it for a number of years on it's side and then re-measured it, and it had warped?
The burden of proof is usually on the person making the claim.

Re: Another myth put out to pasture
 

Molly suggests that those of you who still want to debate the point do a search on "gravity bends a crank", where the subject was exhaustively discussed: http://www.fordbarn.com/forum/showth...ty+bends+crank

Re: Another myth put out to pasture
 

tubman....what were your initial reading of runout on those cranks before your stored them?.....Mike

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Come on guys,
Too many guys on here that apparently have doctorates in metallurgy. If you have .003 runout that means the center journal is .0015 off center. Bolt that center cap and button it up. jmho
John

Re: Another myth put out to pasture
 

Boy, I wish I knew; it would explain a lot of things. At the time (about 25 years ago), a friend of a friend (a Mopar guy) asked me if I wanted 3 8BA's for $100. I said "Sure!" and took them home. I pulled them apart (they all came apart easily), and I covered them with oil, wrapped them in plastic, and stored them away.

If anyone can come up with Fords specifications on acceptable run-out, I'd really appreciate it. The thing to keep in mind however, is that even a run-out measurement of up to .005" would be eliminated by turning the mains .010 under.

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This is the sort of information I'd like to see, not unverified speculation.

Thanks, Jim

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Okay disclaimer. I don't know crap about nothing. But what was Henry factory specs. Were they perfect specimens of a thousands or 10 thou of a inch?

I don't know?

Re: Another myth put out to pasture
 

Sadly age is what really bends a crank...


Sent from my iPad using Tapatalk

Re: Another myth put out to pasture
 

Time to sweep this thread under the bench way too many wannabee crank specialists here must be something in the drinking water. "LOL"

Here is the same argument from 5 years ago http://www.fordbarn.com/forum/showthread.php?t=5509

http://www.abs-products.com/abs_imag...-warehouse.jpg
R

Re: Another myth put out to pasture
 

I have a scientific mind but am not a metals specialist . My scientific mind tells me (with a little help from Harold Sharon) that the elastic range must be exceeded before plastic deformation. The elastic range of metal is huge and hence I believe that the force of gravity is not enough to cause cold creep. If the crank was made of something with a low elastic range eg peanut butter then we would see cold creep. If a crank will cold creep then surely all the camshafts in the world would be bent due to the force of the open valve springs on the cam-not to mention all the axles on parked cars in the world due to their orientation and the weight they are carrying. Again I can't prove this but applying common sense would suggest that cold creep in metal is not true .

Re: Another myth put out to pasture
 

Ronnie,

You are absolutely right about "kicking this thread under the bench". I am very familiar with the thread you are referencing here, which is why I started this one because I had absolute, definitive information on the subject, which was not present in the thread you referenced. Unless someone has solid information to the contrary, I'm done.

Tubman

Re: Another myth put out to pasture
 

Bill, I have an extensive background in tool & die. State indentured. I also have a degree in metallurgy. Spent many years as a tool maker, in charge of quality control of the tooling produced and requisite laboratory inspections of steel, etc.
That being understood (I hope) I can say with certainty that standing a crankshaft on end is the best way to store them.

Ya know, lots of different ways 'work". However, there is only one "best" way.
I try to keep in mind that not everyone graduated at the top of their class. Heck, judging by many of the posts herein, I have to wonder just how many actually graduated.