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 Torque Confusion on Balancer Hub Assembly: Uh-Oh

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Bull

Bull

Posts : 164
Join date : 2013-02-09
Location : MA

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PostSubject: Torque Confusion on Balancer Hub Assembly: Uh-Oh   Torque Confusion on Balancer Hub Assembly: Uh-Oh Icon_minitimeWed Sep 04, 2013 5:30 pm

I'm looking for you guys to confirm that, thanks to being a bonehead, I stripped a bolt and possibly also a bolt hole in the balancer hub assembly.

My RMW has the mechanical fan.  Therefore, it has the extra pulley up front.  Please excuse my large zip ties; that's what I was using to keep the pulleys from turning as I torqued the bolts.
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I was using this diagram in the FSM to guide me as far as the names of the three types of bolts I had; the correct name would allow me to find the correct torque values.
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I have three sizes of bolts; one for the crank snout; three larger for the balancer assembly to crank hub, and three smaller diameter for what I now believe mate the extra pulley for the mechanical fan to the balancer assembly.
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I was using the torque value of 63 ft. lbs for the smaller bolts, being confused I think by what they were in the diagram and torque chart.  The first bolt kept turning with no click from the torque wrench, and I was thinking "hey, this feels like I should have enough by now."  Then, I felt something give and said a few choice words.  I took the bolt out and it has clearly been damaged in the part of the threads just under the head.  Sorry for the blurriness in the one pic.
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It's weird looking.  The bolt still has threads along its entire length, but you can clearly see the threads under the head look coarse and the diameter seems smaller than on the undamaged bolt.  I'm not really sure exactly what happened.


So, am I correct in assuming that there is some other portion of the FSM that covers these extra bolts and different torque numbers for cars that have the mechanical fan option?  

And, am I now looking at pulling the balancer to fix the damaged hole?  I assume it's damaged, since the bolt is stripped.
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200OZ
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200OZ

Posts : 1731
Join date : 2009-08-06
Age : 44
Location : Farmington NY.

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PostSubject: Re: Torque Confusion on Balancer Hub Assembly: Uh-Oh   Torque Confusion on Balancer Hub Assembly: Uh-Oh Icon_minitimeWed Sep 04, 2013 6:23 pm

Never seen a variable pitch bolt, interesting.Wink To answer your question though, GM calls it a crankshaft pulley bolt and the torque spec is 18 lb. ft. The info is in book 1 of the 3 books, in the engine, on-vehicle service section, page 6A4A-12 (1994). Love the panduit straps, good luck.

Mike
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Bull

Bull

Posts : 164
Join date : 2013-02-09
Location : MA

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PostSubject: Re: Torque Confusion on Balancer Hub Assembly: Uh-Oh   Torque Confusion on Balancer Hub Assembly: Uh-Oh Icon_minitimeWed Sep 04, 2013 6:33 pm

Dear Golly; 18 ft lbs and I was shooting for over 60. No 

What an idiot!
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Fred Kiehl

Fred Kiehl

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Join date : 2009-11-13
Age : 70
Location : Largo, FL 33774

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PostSubject: Re: Torque Confusion on Balancer Hub Assembly: Uh-Oh   Torque Confusion on Balancer Hub Assembly: Uh-Oh Icon_minitimeWed Sep 04, 2013 7:09 pm

It is lbs. ft. not ft. lbs. You got lucky, and stretched the bolt instead of breaking it off.
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Bull

Bull

Posts : 164
Join date : 2013-02-09
Location : MA

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PostSubject: Re: Torque Confusion on Balancer Hub Assembly: Uh-Oh   Torque Confusion on Balancer Hub Assembly: Uh-Oh Icon_minitimeWed Sep 04, 2013 7:23 pm

Fred Kiehl wrote:
It is lbs. ft. not ft. lbs. You got lucky, and stretched the bolt instead of breaking it off.
Old habits (ft lbs vs lbs ft) die hard, Fred. I wasn't taught correctly and it stuck, unfortunately. I'll work on it.



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buickwagon

buickwagon

Posts : 954
Join date : 2011-06-10
Location : Muskoka, Ontario

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PostSubject: Re: Torque Confusion on Balancer Hub Assembly: Uh-Oh   Torque Confusion on Balancer Hub Assembly: Uh-Oh Icon_minitimeWed Sep 04, 2013 7:59 pm

The bolt has been tightened past it's yield strenth, so, as Fred correctly pointed out, it stretched. Permanently. If you had not stopped, you would have twisted the head right off and would now be trying to figure out how to extract the broken bit from the crank.

It is possible that the female thread is stripped or damaged, but I would expect to see bits of it in the male thread if that was the case. Try torquing a good bolt in there (to the correct value this time ;-)) to verify. If the thread is stripped, you will have to heli-coil it. I would not trust that spinning bolt with any less of a repair. (but that's just my 2¢)
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