I started a previous thread questioning the need to spend $3.95 each for engine mounting bolts (1973 year) when they should be much less at a local hardware store.

Common reasoning was stick with the genuine part to make sure the bolts conform to specs, unless I actually know what I am buying. Not knowing much about bolt grade markings then I went with the $3.95 parts. Well, turns out they are nothing more than metric class 8.8 common bolts.

How much do these cost at your hardware store? Is there a premium for the black coloring? Or, am I still missing something? I mean the marking on the bolt head should tell it all: medium carbon steel, quenched and tempered, load=85K psi, yield strength=92K psi, tensile strength=120K psi. Even James delivers his motor mounts with class 10.9 bolts.

-Jeff

QUOTE (scruz914 @ Feb 1 2005, 12:48 AM)

...Is there a premium for the black coloring? ... Even James delivers his motor mounts with class 10.9 bolts.

if it's an anticorrosion coating, maybe...

i'm sure James has done his own materials study and i'm not about to second-guess him.

conventional wisdom is that softer, more ductile fasteners are better in mounts than fasteners that are stronger than needed, and brittle. (these things should bend, rather than break...)

i might be tempted to add an anticorrosion coating if i were using a "common" 8,8 fastener, but then i tend to be anal retentive about such things. this is one reason it takes me forever to finish anything, so it's not without its downside ...

The head of that bolt d/n indicate case hardened. You cant always where it even if the shoe fits. OEM ones are hardened.