| Author |
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Reepicheep
| | Posted on Wednesday, April 18, 2012 - 11:20 am: | 
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Milt, your momma dresses you funny. There. Now your post is right on topic. 
Lets take the thread back *off* topic, and talk about stator thermal problem management.
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Timebandit
| | Posted on Wednesday, April 18, 2012 - 02:49 pm: |
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Getting back on topic: Temperature matters. In fact, it's all that matters.
Take a look at the data sheet for the Loctite 648 that I posted in Fitz's motor thread. It shows us that the strength of the threadlocker diminishes as a function of temperature. The aging tests show that at 150*C/300*F the threadlocker is stable over time, but that at 180*C/350*F the threadlocker fails in a time dependent fashion. Within 1000 hours of aging at 350*F, the threadlocker has lost 60% of it's bonding power. And it continues to diminish from that point onward. By the time that you get to 4000 hours you're only left with 25% of the original threadlocker's bonding strength. When looking at the graph, if you assume that you ride at an average of 60 mph, then hours are equal to miles. This is clearly a recipe for disaster. It doesn't surprise me that rotor nuts are failing.
What this tells me is that if your bike is running at 300*F you may be OK, but if it's been running at 350*F for a long time then you may be happy about your stator rewind, but you're still at risk for suffering threadlocker failure. What if your temp is somewhere in between? We have no data to answer that question, but we can assume that a temperature between 300*F and 350*F is going to result in a curve that's in between the red and blue curves on the plot. If the bike's stock temperature curve is anything less than a horizontal line, then we're in trouble. Knowing where we fall on that curve is critical information.
It would really help to know the normal operating temperature of the stator, for several reasons. First, we need to know how hot the stator gets under normal operating conditions to really understand how much the temperature reduction will prolong stator life. Second, we need to know how hot the stator gets to get a better idea of the threadlocking failure problem.
Right now all we know is that Hilde is at about 300*F after his mods, which corresponds to the 150*C curve in the data sheet. We don't know how hot his bike got before, and whether it was above 350*F/180*C or below that. That's critical information to know if you care about the rotor nut failures or about stator life. Sometimes you need to not focus on one thing (a 450*F rating for kapton wire) and look at the bigger picture. |
Dannybuell
| | Posted on Wednesday, April 18, 2012 - 03:42 pm: |
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Timebandit ~ Yes |
Baf
| | Posted on Wednesday, April 18, 2012 - 11:16 pm: |
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@Cravacor - they don't have anything to do with this specifically. The stator cover on my bike has some damage on it though, so I was going to toss a set of CF covers on. |
Timebandit
| | Posted on Thursday, April 19, 2012 - 01:24 am: |
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yes, my only reason to buy the CF covers when i got the rotor was to install them while i had the bike apart. |
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