All you want to know about bolts...Grade 5 or 8 or aircraft or whatever....

[ItBites]

Jerry,

My problem with your posting was that you indicated there is something wrong with grade5 bolts, just because they are grade5. Your assertion was that there is no place for grade5 and if you get a car with grade5 on it, it must be changed. This thinking is not only incorrect, it displays a general lack of knowledge in fastener design. Maybe moron was too strong.

There is nothing wrong with using grade8 anywhere you don't need an even better fastener, like an unbrako. some places, such as cranks and rods and heads need better than grade8, but I suspect you knew that and were generalizing.

It is also true that in many locations, a grade5 fastener is acceptable and safe. It just depends on the loading. This is where I had difficulty with your assertion that all grade5s are dangerous and must be changed to grade8. For example, grade5s are ok for valve cover bolts, where your torque limits the fastener load anyway...

If you like grade8 better in ALL locations that is fine, but just don't go telling everyone that it has to be that way or the car is dangerous unless you've run the appropriate calculations to back up your assertion.

It is true many car builders build fine cars without this skill (you may fall into this category), but to build something superlight, strong and fast, like an indy car, you need to actually engineer it, rather than seat of the pants.

If you'd have expressed your opinion that it is better to use grade8 where you can, then fine, but you had the nerve to tell folks their cars are dangerous if they use grade5 anywhere. You simply cannot justify that statement as it is not fact. Some cars may be dabgerous, some may be just fine.

You have to admit you are not a trained expert in this matter. You can express your opinion, but it its no more than that.

If youd like to learn more it has been suggested that Unbrako fasteners have a pretty good explanation. Unbrakos are likely the best fasteners in the world and they know their stuff.

I know a little as well and have developed standards for aerospace companies and have defined acceptable policies for NASA from time to time. PM me and I'll let you know my credentials, just be sure to let me know yours as well.

Have a nice day