I tend to agree that there are better ways of securing a fastener than a split washer, but for the price and labor, in many cases a split washer is more than adequate. Most of the rationale for not using a split washer I have seen here comes from aerospace and racing applications, and true, you don't see many split washers in these applications. But we're comparing apples and oranges, there is very little similarity between the frame components on a Ford truck and a race car or jet aircraft. A truck is bolted together and will probably never get taken apart, while a race car and aircraft are completely dissasembled periodically. A split washer will gouge out a bit of the material every time the bolt is removed, and after many inspection cycles, this irrepairably damages the part, so some form of self locking nut (installed with a flat washer), adhesive, or safewire method is used to prevent loosening. I think the key here is that these are all just added safety precautions to prevent a fastener from coming apart, the torque applied and bolt stretch are what really keeps things together.

 

I was told by NASA in Greenbelt the reason they don't use split washers, is should the washer split on the other side and wiggle out it would be two very dangerous pieces of sharpnel during acceleration and deacceleration. We got hung up on that when the ruling showed up for the specs on some new AC equipment we were installing. They amended the specs. to allow the split washers.

 

One practical note about using different kinds of bolts on a truck frame: anything that goes on, needs more than one way to come off. I for one would *not* want the task of removing a grade 8 bolt whose fastener end had rounded off...

 

One good thing about grade 8 fasteners; they're a heck of a lot harder to round of in the first place! Once a fastener reaches that point, you'll find they all grind off just about the same, as a matter of fact, harder steel sometimes is easier to grind, as it's less gummy.

 

Can you imagine trying to use the old easy out process with a grade 8? Yuk!!
Maybe the cobalt drills would do the trick. Anyone ever drilled a grade 8?
Pat

 

I've tried drilling crosswise into grade 8s for the purpose of using as holders for my jackstands. (The drill is for the little chain.) Strangest thing...the first one went with a minimum of hassle; the second one broke more bits than I can count. Still not sure what to do about it...

 

Slightly disconcerting, quality control problems no doubt. Seems to me that Grade 8 is probably the wrong bolt to use to replace rivets as the sheer strength of a grade 5 is greater, if memory serves me correctly. A tight fit and a grade 5 with locktite and I really doubt they'll move.
Pat

 

Stainless steel is useful for corrosion resistance, but a poor choice for fastening strength. It is typically weaker than alloy steel. Forget the stainless.

Split washers are worthless for any application where the bolt is under a tensile load.(cylinder head bolts or main bearing bolts for example). The friction between the nut and bolt threads is far higher than any contribution from the split washer. Proper bolt stretch is what you are looking for; this can be imperfectly and indirectly measured with a torque wrench. If the tension in the bolt backs off enough for the split washer to do anything, the value of the bolt is already lost.

Split washers only act to keep the hardware from falling off the truck once the nut has already backed off from where it should be. This is potentially of some value in a shear load situation, as with many (but not all) of the bolts through the frame.