How to determine bolt hardness?

Anonymous Poster · Jun 3, 2003

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

dfeck · Jun 4, 2003

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 · Jun 4, 2003

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

dfeck · Jun 4, 2003

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

Thanks

BillyP · Jun 4, 2003

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

dhvd79a · Jun 4, 2003

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

Darren · Jun 4, 2003

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.