How to determine bolt hardness?

   / How to determine bolt hardness? #11  
How about the nuts? Are they also graded/marked?
 
   / How to determine bolt hardness?
  • Thread Starter
#12  
Well, I checked the head last night and here is what I seen. No "tick" marks and the only marking is "V108" and across from that "8.8". I haven't had the time to talk to my father but this is now a curiosity issue for me. Any ideas on the markings?
 
   / How to determine bolt hardness? #13  
8.8 is the grade of the bolt, it should also be a metric bolt as well.
 
   / How to determine bolt hardness?
  • Thread Starter
#14  
Is a metric 8.8 grade in line with an american standard grade 8?

Thanks
 
   / How to determine bolt hardness? #15  
An 8.8 grade metric is right at a grade 5 SAE.
 
   / How to determine bolt hardness? #16  
Sooooo... Is my metirc 13mm head bolt that is marked 10.8 similar to a REAL grade 8? /forums/images/graemlins/tongue.gif
 
   / How to determine bolt hardness? #17  
If you really want to know how hard a bolt is, many machine shops will have a hardness tester. The markings on the head are no better than the manufacturer. If it's imported from China, be careful about using higher grade bolts in critical applications.
 

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