How to determine bolt hardness?

[Anonymous Poster]

How about the nuts? Are they also graded/marked?

 

[dfeck]

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?

 

[jrlichina]

8.8 is the grade of the bolt, it should also be a metric bolt as well.

 

[dfeck]

Is a metric 8.8 grade in line with an american standard grade 8?

Thanks

 

[BillyP]

An 8.8 grade metric is right at a grade 5 SAE.

 

[dhvd79a]

Sooooo... Is my metirc 13mm head bolt that is marked 10.8 similar to a REAL grade 8? /forums/images/graemlins/tongue.gif

 

[Darren]

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.