Gravity bends a crank?
 

I had my crank reground 4 or 5 years ago and put it in a box to store it. the box is resting on the floor and the crank inside is parallel to the floor. Is there any truth that all crankshafts should be store vertically?:confused:

Re: Gravity bends a crank?
 

Yes. I would definitly check it carefully before you decide to use it. In the meantime, stand it up!

Re: Gravity bends a crank?
 

agreed, there is truth to this, if it is not properly supported while being stored horizontally.

Re: Gravity bends a crank?
 

This is one of the topics that there is little agreement on, but most believe that the sagging crank theory is a myth. Easy enough to check, run a gauge on it and see what you have.

Re: Gravity bends a crank?
 

I'm concerned now... Will climate change bend my crank?

Re: Gravity bends a crank?
 

No, but if global warming causes the seas to rise enough to flood Salt Lake City, it will rust.

Re: Gravity bends a crank?
 

Well OK then. I will rotate the box 180* and wait another couple of years. If it is sagging this should fix it.

Re: Gravity bends a crank?
 

Uncle max, The coefficient of thermal expansion of steel is such that unless the extreme temperature is sustained, thereby not permitting the crank to return to its nominal size, the distortion will remain. At least that's my view.
Think of a rail road track expanding during summer and contracting during winter. I just realized you are joking?

Re: Gravity bends a crank?
 

on larger (non-automotive) engines, you have jacking gear to turn them over slowly after they have been sitting for a while to remove any distortion from gravity, and this is a crank that is supported. no doubt in my mind that same doesn't happen to an unsupported one. the question becomes what is tolerable. may never even notice it? i can't answer that. but i have to believe that there is measurable change there. if it were a 9000 rpm racing engine, there is probably something to be worried about. these engines, maybe not.

Re: Gravity bends a crank?
 

It all depends how many Leap years were in the laying down cycle :eek:

Re: Gravity bends a crank?
 

I would think that if gravity bends a crank laying on its side too long that standing it on end too long will cause its diameter to spread. . . kinda like my diameter has spread from standing on my end too many years. :rolleyes:

Re: Gravity bends a crank?
 

fify

Re: Gravity bends a crank?
 

I had to look that one up, Alan. DD

Re: Gravity bends a crank?
 

Re: Gravity bends a crank?
 

I got 'er figured-out......had just never seen that one before. What the heck do I know? DD

Re: Gravity bends a crank?
 

I have always been amazed at discussions like this. Here's a crankshaft that can take the firing impulses running in an engine for 90-100K miles, and some prople wwill think it will bend sitting on a floor? Give me a break!

Re: Gravity bends a crank?
 

Soooo, are ya saying cranks don't twist with each firing impulse? There's a difference between "bend", "twist" and "yield point". You ever think about what a harmonic balancer does in conjunction with a crank? DD

Re: Gravity bends a crank?
 

Gravity is considerably weaker than the forces that hold matter together. The nuclear force being the greatest. You would think the bonds of the molecules in the metal would be many orders of magnitude greater than the pull of gravity on a small tab.
Perhaps it the tab was over a foot then with time it could sag under its weight, and long distance to its connection to the shaft!

Re: Gravity bends a crank?
 

Man, you fellers is SMART !!!! By th way, what's a "molyquals"?

Re: Gravity bends a crank?
 

Molly Cules...she worked at the cafeteria next to the crankshaft foundry at the Rouge plant. Was said to have inspired the workers to make sure their crankshafts were always straight, even if they were laid flat.

Re: Gravity bends a crank?
 

If she's the same Molly I once knew, she personally bent many a shaft in her time.

Re: Gravity bends a crank?
 

In the scifi film Forbidden Planet several space ship engineers were commenting on a new piece of scientific equiptment and one said,
I bet every Quantum Mechanic in the force would love to get his hand on this!
Funny

Re: Gravity bends a crank?
 

Know that's some funny stuff that there is.

Re: Gravity bends a crank?
 

Still many strange and unknown things exist. Maybe there is an unknown property of the metal in the crank that could create some strange phenomena so you better store your your crank in the vertical position just to be safe. After all, science for over a hundred years could not account for the fact that bumble bees can fly because their wings are too stubby to lift their big body aerodynamically...
But with recently with ultra high speed photography they found that the bumble bee does not flap his wings up and down as previously thought but rather front to back. So aerodynamically the bumble bee should not be able to fly but accounting for fluid flow dynamics of air with front to back flapping, more lift is actually generated. Maybe some day aircfaft designers will employ this principle to generate aircraft with greater lifting capacities.

Re: Gravity bends a crank?
 

At the risk of getting serious, years ago my buddies and I bought a NOS 99A crankshaft from the Ford dealer in Pinedale, WY. It was in a wooden shipping box which obviously was intended to be shipped and stored in a horizontal position, suggesting Ford wasn't very concerned about the effect of gravity on its famously stout crankshafts.

Re: Gravity bends a crank?
 

HAHAHAHAHAHAHAHAHAHA-puke-HAHAHAHAHAHAHA

Re: Gravity bends a crank?
 

I feel better storing a crank laying on the floor, if I store anything standing up I'll knock it over before I get around to using it.

Re: Gravity bends a crank?
 

True, if you store it balanced on edge it may fall over and break something.

Re: Gravity bends a crank?
 

In the past a picture was posted here on the 'Barn showing a rack that would hang the crank by it's flange. Do you s'pose they will stretch?

Re: Gravity bends a crank?
 

So it's true if you lave a crank laying on its side long enough it will eventually turn into flat steel plate as it succumbs to the evil forces of gravity. I stand mine up cos it's more convenient.

Re: Gravity bends a crank?
 

Cast iron cranks will definitely sag if stored horizontally and not supported correctly! The longer and heavier they are the more apt they are to sag. If you don't believe it you just haven't experienced it yet.
A Model A crank which is shorter, lighter and made of steel is not so apt to sag if stored horizontally.
Bill

Re: Gravity bends a crank?
 

And you base this assertion on what empirical evidence?

Re: Gravity bends a crank?
 

Now all us old guys have a reason for our middles being thicker, Gravity is squeezing our ends together and that is over a period of 60 years!!

Re: Gravity bends a crank?
 

Only if your middle is made of cast iron and you spend a lot of time in the horizontal position.

Re: Gravity bends a crank?
 

Sixty three years actual experience building engines, from flatheads to diesel engines and aircraft engines.

How about your actual engine building experience?
Bill

Re: Gravity bends a crank?
 

It pales by experience. If you know for a fact, based upon 63 years of building engines, that storage of a flathead Ford V8 crank in a horizontal position results in a bent shaft, I guess that ends the debate. Still, your certainty on the point does beg the issue of how long a Ford flathead V8 crank must lay in a horizontal position before it is ruined by gravity. Are we talking months, or years?

Re: Gravity bends a crank?
 

Store it in whichever position is most convenient.

They're stored on end at machine shops because they take up less floor space, not because of any distortion concerns. If any bending due to horizontal storage is a concern, then distortion due to vertical storage should be an even bigger one, as it would cause all the journals to bend.

Re: Gravity bends a crank?
 

I'm not saying the crank is ruined, I'm saying it will sag if not properly supported. When it is in the engine it is supported by the main bearings. Laying horizontal on the floor or bench it is supported on a couple of counterweights
When I first became aware of the problem it was a fresh ground cast iron 6 cyl crank. I installed it in the block and when I torqued it up it locked up. When I loosened the caps it turned but not freely I removed the maincaps and checked the runout with a dial indicator, It had about.005 . My first thought was the crank grinder had some how screwed up. I left it laying the block for a few days while working on another job. When I came back and tried it again it turned freely so I torqued it up and it still turned freely. This crank had laid on a steel workbench unsupported for probably 2 months since returning from the crank grinder. When it was installed in the block and properly supported for a few days the sag disappeared.

Just to clarify, Gravity will cause a crankshaft to sag, not bend. And the problem is worse on a cast iron crank than a steel crank. Also the problem is worse on a long crank than a short crank.
A Ford V8 crank stored horizontally and "properly supported" would not have a problem, If improperly supported could have a problem.
Most crank grinders store them vertical to prevent that problem. Bill

Re: Gravity bends a crank?
 

I have machined Flathead cranks from all walks of life and found absolutely no difference related to storage conditions. Frankly, the cast iron crank might be LESS likely to "sag" than the steel crank. If gravity damages a crank in the horizontal position just imagine how badly damaged it will be when stored on end!! If you have ever straightened the crank from a wrecked engine in a crank press you will see how far it must be moved to overcome "spring-back".

Re: Gravity bends a crank?
 

With all respect due you - - - - isn't this sending a mixed message ?