Gravity bends a crank?

J

jonf

Junior Member
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:
 
jonf said:
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:
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Yes. I would definitly check it carefully before you decide to use it. In the meantime, stand it up!
 
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.
 
No, but if global warming causes the seas to rise enough to flood Salt Lake City, it will rust.
 
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Well OK then. I will rotate the box 180* and wait another couple of years. If it is sagging this should fix it.
 
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?
 
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.
 
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:
 
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!
 
tubman said:
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!
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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
 
tubman said:
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!
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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!
 
FrankWest said:
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!
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Man, you fellers is SMART !!!! By th way, what's a "molyquals"?
 
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.
 
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