revisit : gravity bends a crank

A

al pa.

Senior Member
gravity may very well bend a crank stored horizontally.a very large electrical manufacturer,producing large generators for powerplants,would leave armatures in process of machining,rotating on a lathe,even when the plant was inactive(holidays,weekends,shutdowns,etc.)these large forgings would develop runout if left hanging stationary on lathe centers.
 
al pa. said:
gravity may very well bend a crank stored horizontally.a very large electrical manufacturer,producing large generators for powerplants,would leave armatures in process of machining,rotating on a lathe,even when the plant was inactive(holidays,weekends,shutdowns,etc.)these large forgings would develop runout if left hanging stationary on lathe centers.
Click to expand...
And of course the NASA space program is now renting out crankshaft sized cubicles that are being placed in orbit for those who wish to eliminate gravitational pull on their crankshafts.
 
Yep! A couple more flathead cranks destined for zero gravity:):D
 

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I have 2 8BA cranks that have been lying in their sides on the floor of my shop for close to 20 years. Next week, I will be bringing them in to be checked to see if they can be used in an engine I am building. I will be having the runout of the main bearings checked. Then I think we should know for sure.

An interesting fact is that the '49-'51 Ford shop manual gives a technique for checking a block for crank runout, but not the crank itself. (Their solution if it is not in spec? Replace the block!)
 
"An interesting fact is that the '49-'51 Ford shop manual gives a technique for checking a block for crank runout, but not the crank itself. (Their solution if it is not in spec? Replace the block!)"

That's strange. We were sleeving main bearing saddles in the 50's so the technology was current.
Must have been a marketing thing.
 
That might be another reason why you could buy semi finished main bearings, so you could bore them to compensate for mis aligned block main tunnels?????
 
Pete said:
"An interesting fact is that the '49-'51 Ford shop manual gives a technique for checking a block for crank runout, but not the crank itself. (Their solution if it is not in spec? Replace the block!)"

That's strange. We were sleeving main bearing saddles in the 50's so the technology was current.
Must have been a marketing thing.
Click to expand...

Pete, that one went right over my head. Maybe OT, but could you expand a little on how to sleeve a main? What holds the sleeve in place? Thank you.
 
Is there anyone here who has had to throw away a crank because it was not stored properly? Installed an improperly stored one and ruined a new motor? A very large armature has a lot of weight in the middle of a much longer shaft. They could have sized a larger shaft but did not need to and had significant weight savings.
 
bobH said:
Pete, that one went right over my head. Maybe OT, but could you expand a little on how to sleeve a main? What holds the sleeve in place? Thank you.
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The saddle is bored oversize to fit a chosen cylinder sleeve or in some cases a special sleeve is made from cast iron.
The sleeve is cut in half plus kerf. It is set in the saddle and several holes are drilled through the sleeve and into the block about a 1/4 inch. Brass rod is cut into appropriate lengths to use for rivets. The rivets are installed and peened over. The excess sleeve is surfaced flush to the pan rail or block surface.. The mainline is then bored to finish size.
Carrier bearing bores in rear ends are fixed the same way.
 
al pa. said:
gravity may very well bend a crank stored horizontally.a very large electrical manufacturer,producing large generators for powerplants,would leave armatures in process of machining,rotating on a lathe,even when the plant was inactive(holidays,weekends,shutdowns,etc.)these large forgings would develop runout if left hanging stationary on lathe centers.
Click to expand...

What's your point? Gravity will also bend a crank stored vertically. It will also cause a bend in a toothpick.

Whether or not the deflection caused by gravitational forces is an issue or not is relative to the magnitude of the deflection and the application. In the case of an automobile engine, any deflection caused by either storage method is a non-issue.
 
I think if you had a crank shaft ground and put it in the engine the caps tightened up would bend it back and the centrifugal force and heat would be ok.
I think this is a bunch of old tales.Like they used to say if you took the dist out it would never run agsin.And the other stupid thing was and engine runing backward. Seems it not oil and more.
 
Just received a Western Union telegram from Molly: "Boys, I've really enjoyed all this talk about crankshafts. Stop. Brought back some great memories. Stop. Hope you enjoy your V8's, whether your cranks are straight or not. Stop. For God's sake, stop. Love, Molly. Stop."
 
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