What Does 8.8 Mean On A Metric Bolt

[Morris]

What does 8.8 mean on a metric bolt? Should I be using 10.9s or 8.8s to work on my newer equipment?

 

[IH tractorman]

that is the hardness I don't know the spec, but I think around a grade 5 for 8.8, grade 8 for 10.9

 

[oldihdsl]

What does 8.8 mean on a metric bolt? Should I be using 10.9s or 8.8s to work on my newer equipment?

 

[oldihdsl]

Hardness. 10.9 is harder than a 8.8. A bolt used in a pulley will run longer theorticaly where as a 10.9 will be used when cost is a factor or strength is a primary consideration. You would not want to use a $10.00 bolt in a $5.00 apl.