Storing crank shaft, can it warp?

[tan top]

yes they can warp...    shops usually stand them upright or sometimes hang them

     yes they warp   i've always  put an old balancer/ pulley back on the crank ,stand it up on a block wood , cover it with greese then put a plastic  over it, / if its a spare crank or you are not using for a while .

[RD]

hate to bring this old topic up, but here it goes:

According to the SUNNEN Manual for a Model DCB-750 crankshaft balancing machine, if:

"the crankshaft has been in the balancer for more than 4 hours:  (a) it is best to spin crank approximately 3 time's for it to 'straighten itself from any flexing which may have occurred."

There ya have it...

[Ghoste]

But does the manual tell you if it can take a set and stay warped??

[Rack]

I have an idea...


Every one at this site can pitch in an equal amount of money, and one of the mods can purchase a crank shaft.


That mod will then lay the crank shaft on it's side and take measurements every month to monitor whether it is warping or not. He will do this for a year.


If it hasn't warped in one year, it ain't gonna.


And since this is my idea the mod can then send me the crank shaft after the experiment is over. 

[RD]

But does the manual tell you if it can take a set and stay warped??

no it does not state anything to that regard.  the statement found in the manual was shown just to show all the naysayers that "yes, a crankshaft can warp/flex when laid on its side."

[smasherofall]

I guess I should stand mine up, I have room next to the batteries on the concrete floor.

[max]

i emailed this question to an engineer friend of mine who is also a fellow mopar lover and this is his take on the question and it makes alot of since when you read it.

My take on this is that if the crank is wimpy enough to bend standing up or laying on it's side, then it would never survive in an engine.  It is true that the crank will flex (ever so slightly), but it should be within the elastic range of the metal.  Typical most metals including steels have an elastic range that is linear up to the point engineers call the yield point.  Once you go past the yield point, the metal is permanently deformed.  This is referred to as plastic deformation.  I think plastic has a latin root that means to form or be formable.

Think of a piece of thin sheet metal.  You can flex the metal a little and it will spring back.  Bend it a lot and it is permanently bent and you can not really put it back into it's original form because on the outside of the bend, the metal is stretched, and comressed on the inside of the bend.

Think of how much force is on each piston and rod pushing on the crank and compare that to the 50-75 pounds of force due to gravity.  In a running engine, you would have bending loads caused by the offset between the rods and mains, but also torsional stresses front to back due to a resistive load applied at the flange (assuming you are not on ice and flooring the throttle) and the forces on the crank trying to overcome the resistance.  I would assume that the stresses in a running engine would be thousands of times higher than that of gravity trying to bend your crank.

[RD]

i emailed this question to an engineer friend of mine who is also a fellow mopar lover and this is his take on the question and it makes alot of since when you read it.

My take on this is that if the crank is wimpy enough to bend standing up or laying on it's side, then it would never survive in an engine.  It is true that the crank will flex (ever so slightly), but it should be within the elastic range of the metal.  Typical most metals including steels have an elastic range that is linear up to the point engineers call the yield point.  Once you go past the yield point, the metal is permanently deformed.  This is referred to as plastic deformation.  I think plastic has a latin root that means to form or be formable.

Think of a piece of thin sheet metal.  You can flex the metal a little and it will spring back.  Bend it a lot and it is permanently bent and you can not really put it back into it's original form because on the outside of the bend, the metal is stretched, and comressed on the inside of the bend.

Think of how much force is on each piston and rod pushing on the crank and compare that to the 50-75 pounds of force due to gravity.  In a running engine, you would have bending loads caused by the offset between the rods and mains, but also torsional stresses front to back due to a resistive load applied at the flange (assuming you are not on ice and flooring the throttle) and the forces on the crank trying to overcome the resistance.  I would assume that the stresses in a running engine would be thousands of times higher than that of gravity trying to bend your crank.

Those are good points.  I am no engineer, nor do I claim to be, but within an engine, the forces are constantly being equalled out (as close as possible) by the opposing forces from other cylinders acting on the crank in a synchronous manner.  The fact that the crankshaft is supported in 5 areas that allow for no up/down/side to side movement also allow for stability.  This is all not including the fact that the crankshaft is rotating and the inertia caused from this rotation allows for the crankshaft to remain to its true form.

I am not saying that the stresses of the engine do not have an effect.  What I am saying is that the crankshaft was made to work in that environment under those stressors.  It was not made to lie on its side and have its weight being focused on areas (i.e. counterweights) where its weight was not intended when engineered.  The crankshaft was engineered so that its weight would be supported by hardened main journals, not unhardened counterweights.

Your friend did state that a crank could flex ever so slightly.  Well, in engine building realms, ever so slightly will either give you a vibration or cause you to have to regrind yoru crankshaft due to the specific tolerances needed.

just my 2 pennies.

[max]

i emailed this question to an engineer friend of mine who is also a fellow mopar lover and this is his take on the question and it makes alot of since when you read it.

My take on this is that if the crank is wimpy enough to bend standing up or laying on it's side, then it would never survive in an engine.  It is true that the crank will flex (ever so slightly), but it should be within the elastic range of the metal.  Typical most metals including steels have an elastic range that is linear up to the point engineers call the yield point.  Once you go past the yield point, the metal is permanently deformed.  This is referred to as plastic deformation.  I think plastic has a latin root that means to form or be formable.

Think of a piece of thin sheet metal.  You can flex the metal a little and it will spring back.  Bend it a lot and it is permanently bent and you can not really put it back into it's original form because on the outside of the bend, the metal is stretched, and comressed on the inside of the bend.

Think of how much force is on each piston and rod pushing on the crank and compare that to the 50-75 pounds of force due to gravity.  In a running engine, you would have bending loads caused by the offset between the rods and mains, but also torsional stresses front to back due to a resistive load applied at the flange (assuming you are not on ice and flooring the throttle) and the forces on the crank trying to overcome the resistance.  I would assume that the stresses in a running engine would be thousands of times higher than that of gravity trying to bend your crank.

Those are good points.  I am no engineer, nor do I claim to be, but within an engine, the forces are constantly being equalled out (as close as possible) by the opposing forces from other cylinders acting on the crank in a synchronous manner.  The fact that the crankshaft is supported in 5 areas that allow for no up/down/side to side movement also allow for stability.  This is all not including the fact that the crankshaft is rotating and the inertia caused from this rotation allows for the crankshaft to remain to its true form.

I am not saying that the stresses of the engine do not have an effect.  What I am saying is that the crankshaft was made to work in that environment under those stressors.  It was not made to lie on its side and have its weight being focused on areas (i.e. counterweights) where its weight was not intended when engineered.  The crankshaft was engineered so that its weight would be supported by hardened main journals, not unhardened counterweights.

Your friend did state that a crank could flex ever so slightly.  Well, in engine building realms, ever so slightly will either give you a vibration or cause you to have to regrind yoru crankshaft due to the specific tolerances needed.

just my 2 pennies.

i know what you mean, i'm not an engineer either and as the points suggest there has to be certain bit of flexing for the crank or it would not be able to handle the stress of the rotating assembly.

if it didn't move or flex and take up the shock of the rotating assembly the crank would certainly break.

from the information that has been posted on this subject here and from others it suggest to me that indeed laying a crank on it's side would cause it to warp. 

based on the information suppied i will continue to stand my cranks up plus they take up less room that way.

[AKcharger]

wow this is still alive? I think I'm going to store it at a diaginal so either way it will be right

[SeattleCharger]

I guess I should stand mine up, I have room next to the batteries on the concrete floor.

I have heard standing it up is important, and I have also heard from a long time mechanic/rebuilder/teacher that it doesn't matter.    I don't know, but better safe than sorry if you have to choose a way.