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Old 03-12-2021, 21:35   #1
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Isolated ground post sheared off

Absolutely livid at the moment I was remounting my nearly brand new balmar 60 series 100 amp alt after fixing the belt alignment and the grounding post sheared off at 13ft lbs!!!!!!!!! 13!!!!! THE POSITIVE WIRE IS OK AT 25 BUT 13 ON THE NEGATIVE RUINS IT?!?!?
IF THE POST IS THAT FLIMSY SPECIFY A TORQUE.

Do I have any recourse in this? I was supposed to complete a sail tomorrow but this ruins that. And now I probably need a new alternator. Lovely.
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Old 03-12-2021, 21:56   #2
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Re: Isolated ground post sheared off

An auto electric shop can rebuild/replace the post for very little (I think).
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Old 04-12-2021, 19:44   #3
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Re: Isolated ground post sheared off

Quote:
Originally Posted by Notyetsinking View Post
Absolutely livid at the moment I was remounting my nearly brand new balmar 60 series 100 amp alt after fixing the belt alignment and the grounding post sheared off at 13ft lbs!!!!!!!!! 13!!!!! THE POSITIVE WIRE IS OK AT 25 BUT 13 ON THE NEGATIVE RUINS IT?!?!?
IF THE POST IS THAT FLIMSY SPECIFY A TORQUE.

Do I have any recourse in this? I was supposed to complete a sail tomorrow but this ruins that. And now I probably need a new alternator. Lovely.



Well, you applied too much torque. Balmar uses M8 x 1.25mm bolts for output connections.


https://www.fastenal.com/content/mer...ce%20Guide.pdf


From the chart, at M8, for class 8.8 bolts you would use no more than 16 ft-lbs assuming a K factor of 0.17. Did you apply any sort of threadlocker or lubricant? That reduces the torque you should use. Maybe Balmar uses class 4.6 bolts, I don't know and their publications don't specify, those have a maximum torque less than half the more common class 8.8 bolts.


Anyway, an auto electric place should be able to replace the stud for you.
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Old 06-12-2021, 08:16   #4
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Re: Isolated ground post sheared off

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Originally Posted by Jammer View Post
Well, you applied too much torque. Balmar uses M8 x 1.25mm bolts for output connections.


https://www.fastenal.com/content/mer...ce%20Guide.pdf


From the chart, at M8, for class 8.8 bolts you would use no more than 16 ft-lbs assuming a K factor of 0.17. Did you apply any sort of threadlocker or lubricant? That reduces the torque you should use. Maybe Balmar uses class 4.6 bolts, I don't know and their publications don't specify, those have a maximum torque less than half the more common class 8.8 bolts.


Anyway, an auto electric place should be able to replace the stud for you.
It wasn’t the bolt that had the issue, the rectifier had a solid metal “lip” where the negative cable connects to the common ground, and that lip tore off.

I forgot about those bolt torque charts and I should have checked there. However that would not have helped here, as again the solid metal attachment point failed. Interesting on the max torque as they did specify the positive output and that was more than 16. Luckily It looks like I can replace the rectifier individually as Balmar does sell those pieces individually.
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