Could somebody explain what are those bolt-grades? I know what they are, I'm just having trouble convering something what you call a "grade 8 bolt" to something metric. Is it width? Length? Some ratio between width & length?
the grade of the bolt refers to its properties.. mmm.. its breaking strength.. basically how tough they are... grade 8 is stronger than grade 5...
the reason on the same bolt in different grades.. the differences in the thread length.. is because of the strength properties.. thats why grade 8's have less threads on the longer bolts.. its part of them being stronger..
they make standard and metric in all grades..
here is a website.. with some information for you.. http://www.rightcoastcrawler.com/bil..._Fasteners.htm