Hair-line cracks in crank arm? Safe to ride?
06-14-19, 07:29 PM
#26
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06-14-19, 07:45 PM
#27
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This situation reminds me of this morning as I got in my old Lincoln to drive to our club's Fast Fridays ride.
I went to start the car, but it would only crank, no sign of fuel+spark!
So the ride was nixed, I did some diagnostics and prepared to replace my Crankshaft position sensor, a 1-2 hour job.
When I was under the car with the shield off, I first removed the wire connector before removing bolts to move the AC compressor out of the way.
I then thought to jiggle and remove/reinstall the connector then try to start the car, ...and it started!
But it gnawed at me to think if this possibly-intermittent sensor quits again while I am out of town, ...I wouldn't sleep thinking about it!
So I rode my bike to the auto parts store, bought the $30 sensor and went to work.
I can't express how HAPPY I am that this occurred in my driveway, ...and not somewhere else.
Get the point?
I went to start the car, but it would only crank, no sign of fuel+spark!
So the ride was nixed, I did some diagnostics and prepared to replace my Crankshaft position sensor, a 1-2 hour job.
When I was under the car with the shield off, I first removed the wire connector before removing bolts to move the AC compressor out of the way.
I then thought to jiggle and remove/reinstall the connector then try to start the car, ...and it started!
But it gnawed at me to think if this possibly-intermittent sensor quits again while I am out of town, ...I wouldn't sleep thinking about it!
So I rode my bike to the auto parts store, bought the $30 sensor and went to work.
I can't express how HAPPY I am that this occurred in my driveway, ...and not somewhere else.
Get the point?
06-14-19, 08:54 PM
#28
Senior Member
Yes, my research on the Web (and some posters here) indicate that the Mighty breaks at the end of the fluting design near the pedal. It really looks like its on the surface.
In addition....the original owner (and only owner) is a guy of slight build. Maybe he had a different build years ago, but this fellas is several inches smaller than me. His son was there when I bought the bike. Again, his son (probably in his mid 30s, is not a big guy; maybe 165lbs and 5'9-10". The origjnal owner was a recreational rider; i just think he never used this bike hard.
In addition....the original owner (and only owner) is a guy of slight build. Maybe he had a different build years ago, but this fellas is several inches smaller than me. His son was there when I bought the bike. Again, his son (probably in his mid 30s, is not a big guy; maybe 165lbs and 5'9-10". The origjnal owner was a recreational rider; i just think he never used this bike hard.
Cranks can break at or near the pedal eye, in the middle of the shaft, or at the spider like this one. They will eventually break from a crack at the spider, but it takes longer. As I said, this one is far along; it could break at any time.
06-14-19, 10:38 PM
#29
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Bummer that yours probably isn't trustworthy.
I've got a Sugino GT, and I've long lusted for the lighter, sexier Mighty Tour.
06-15-19, 06:34 AM
#30
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Murphy is the guy who wakes up on his head because his Murphy Bed folded up while he was sleeping.
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Capo: 1959 Modell Campagnolo, S/N 40324; 1960 Sieger (2), S/N 42624, 42597
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"Far and away the best prize that life offers is the chance to work hard at work worth doing." --Theodore Roosevelt
Capo: 1959 Modell Campagnolo, S/N 40324; 1960 Sieger (2), S/N 42624, 42597
Carlton: 1962 Franco Suisse, S/N K7911
Peugeot: 1970 UO-8, S/N 0010468
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06-15-19, 07:50 AM
#31
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the story of Murphy's law was that he caused a batch of failures by not considering what might go wrong. They named the law after him.
Campagnolo cranks crack at the intersection of the spider and the crank arm. People grind those cracks out. There is plenty of material, they crack because the interface is too sharp. This looks too big to safely remove. You can try it, I suppose. It certainly looks like a fatigue crack that has propagated quite far. It's really hard to remove all of a crack. It gets pretty small at the crack tip and the material is pressed together by the plastic zone. You might be able to see it under magnification, not sure.
Campagnolo cranks crack at the intersection of the spider and the crank arm. People grind those cracks out. There is plenty of material, they crack because the interface is too sharp. This looks too big to safely remove. You can try it, I suppose. It certainly looks like a fatigue crack that has propagated quite far. It's really hard to remove all of a crack. It gets pretty small at the crack tip and the material is pressed together by the plastic zone. You might be able to see it under magnification, not sure.
06-15-19, 05:25 PM
#32
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The possibility of a catastrophic failure of the bottle opener is something to keep in mind, though.
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06-03-20, 08:49 PM
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06-04-20, 07:09 AM
#35
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I think everyone said what needed to be said in this zombie thread - except from a semantics point of view.
From the looks of it, it seems as if the crack started at a casting void and is working its way through the arm. Given that there are two very clear voids right below the crack, it's not out of the question to say that this particular crank was probably defective when new.
-Kurt
From the looks of it, it seems as if the crack started at a casting void and is working its way through the arm. Given that there are two very clear voids right below the crack, it's not out of the question to say that this particular crank was probably defective when new.
-Kurt
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