Posted by chriscase on Saturday, January 13, 2007 at 17:56:13 :
In Reply to: Fly wheel bolts? grade 8? posted by mclark on Saturday, January 13, 2007 at 13:09:34 :
Every mechanic ought to have a set of dial calipers. Lots of precision stuff on a truck.
But to digress, be very cautious with fly wheel bolts. If you use an undersize bolt in a threaded hole because it looks like the right size, you may be asking for trouble.
Grade 8's are not lower in shear strength. They have less elongation, so they won't sttrretch, just snap. But bolts shouldn't use shear at all to hold things together. They use the friction between the parts. The bolts just pull the parts together, thereby causing friction. Rivets do the same, being put in hot and shrinking, thereby pulling the parts together. If you flywheel depended on shear, that would mean the flywheel would move back and forth with each power stroke, wearing the holes and loosening the bolts. There lurks disaster...