Leaf sprung A arm bolt washer and nut question

[Dan Case]

Originally Posted by MAStuart

Thanks Dan I kind of thought they should be soft. The plans that I am working off of they say a good substitute to use is a grade 8 shoulder bolt. But I thought to use it in single shear they would maybe brake off. On your cars is the washer that hold the A arm on just a flat washer?
Mark

The road spring and upright assemblies carry most of the loads. I know of original cars that suffered grave control arm problems from factory welds failing, tie down/tow chain damage, severe rusting (one tube rusted because a poor weld didn't seal the assembly) a tube down to almost no wall thickness left, poorly engineered owner modifications, and or in some combination crash damage and yet the frame mounts and pins were still in good condition.

I would recommend doing research on every fastener application in any vehicle suspension system. Steel companies and fastener companies offer help in making material and properties selections but be warned they will probably still leave final decisions to the user for legal reasons.
Some really important things to consider:
1) Just because a fastener is marked and or sold as “Grade such and such”, doesn’t mean it is right for your application.
a. Specifications revolve around a few characteristics and the one that is important for the application you have in mind might not be one of those specifications. Examples: A medium range bolt might bend or stretch while an ultra high strength one might break as its failure happens.
b. Just because a bolt is marked “Grade whatever” doesn’t mean it is. Counterfeiting fasteners is a multiple billion dollar a year industry on its own.
2) Know where your fasteners really come from. Just as “Grades” are faked so are manufactured by names. The genuine company has lots to lose if its products fail in use while the counterfeiter doesn’t.

What you are calling a washer is a thick mild steel disc and captures the end of the a-arm bushing on the threaded end of the pin side. The thread end of the pin is BSF.