[ItBites]

Folks,

If you're not a trained and experienced Engineer familiar with bolted joint design, you should not be dictating which fastener to use for a given application - that includes you jerrywacker. You are a moron if you think that it is never OK to use grade5. I think what you are saying is that since you have no idea how to correctly characterize the loading in a bolted joint, you have to fall back on a philosophy to just overkill all joints. This is actually not a bad approach, given a lack of any better understanding. But you can't claim that a grade5 bolt in a given application is not satisfactory unless you've determined the loading in the joint, the resultant required preload to prevent gapping, the pullout capability of the mating threads, the spring constant of the grip length, the effective spring constant of the clamped members, etc... I have seen no evidence you have any capability to perform these calculations, so stop giving advice.

I do have to add that a statement that only fine threads are acceptable is ludicrous. I'm not sure where jerrywacker got his engineering degree and training, but any Engineer worth his salt will tell you this is not true and each application should be evaluated and then a proper fastener selection can be made.

Sounds to me like this jerrywacker is just a typical carbuilder hack that does no real Engineering and relies on some general rules of thumb that will (admittedly) generally result in a joint that does not fail. This approach is not Engineering or scientific.

Now, I must say that I do not know if the Kbros are any better, but they did not purport to be some bolt expert, giving stupid advice to folks here.