BMW Nuts @ Bolts

[DesertEagle50]

Hey,
I recently removed the intake manifold and need to replace a few nuts that have seen better days. My issue, though, is larger than a few nuts. I use RealOEM.com to assist with parts orders. I'm getting tired of looking up nuts and bolts to find replacements and seeing cryptic codes. For example, see
http://www.realoem.com/bmw/showparts.do?model=AF93&mospid=47305&btnr=11_0953& hg=11&fg=40[/URL].
Does anyone know if there is a key that defines these abbreviations? I mean, what is M6X25-ZN, M8X50-Z1-ZNS, AM7, or BM7? I know that these are M6, M8, M7, and M7 threads, respectively, but that's it. I'd really like to learn BMW-ese so I can make some sort of determination whether I need the exact part or if I can substitute a comparable fastener. Thanks!

[dandrewg]

In a screw that is M6X25-ZN, M6 means the nominal diameter is 6mm and you can assume the 25 is length in millimeters. Sometimes with fasteners with multiple pitches you will see say M12X1.5 where the 1.5 is the thread pitch, meaning there is 1.5mm between each thread (M12's also come in 1.25mm and 1.75mm thread pitch). And I would assume the ZN means that the fastener is made out of zinc. Not sure about the AM7 or BM7 though, could relate to the hardness.

[e30Matt]

ZN means it's zinc-dichromate plated. Resists corrosion, it's the "gold" fasteners you see all over the engine bay.

[DesertEagle50]

ZN means it's zinc-dichromate plated. Resists corrosion, it's the "gold" fasteners you see all over the engine bay.

Where can I find out the rest of these abbreviations, such as ZNNIV, Z1, etc?

[e30Matt]

I just remember them from looking at fasteners in bags at the parts counter. Asking a parts guy would be your best bet.