Hex Nut Question

[clonmore1]

Can anybody please explain what the ZNS & ZNS3 refers to or stands for?

I am looking to purchase fasteners for the rear subframe and looking at Realoem under rear frame, these are in the supplement column against the exploded drawing.

I can't seem to locate these on an internet search, am I missing something or just being as stupid as normal ?

Thanks

[montmil]

Pretty much all you need is right here:

http://www.advrider.com/forums/showthread.php?t=373090

[Lucky_Lou]

I have tended to replace everything with stainless steel, Bapp are as cheap as chips and a branch on Huddersfield road Barnsley
http://www.bapp.co.uk/
Lou

[Barry]

Can anybody please explain what the ZNS & ZNS3 refers to or stands for?

They are BMW's own internal standards for zinc coating. As far as I can make out  ZnS is short for Zinc Sulphide.

Assumming they are the sub frame mounting bolts they are safety critical so I would only worry about the grade of the bolt. What are they 8.8 or 10.9 ?   If they are 10.9 you won't be able match them in stainless. The very best A4-80 stainless bolts just about match 8.8 for strength.

[montmil]

When swapping out fasteners -either steel or stainless- always be aware of what is know as the "grip length" of a bolt or machine screw. That's the unthreaded portion of the shank that is often used as a load bearing component between two or more parts. Threaded shanks placed in these specific attach points are not load bearing and could lead to the rapid wear of the threads; followed by a loosened or failed junction.

Grip length is determined by the thickness of the pieces to be joined plus the thickness of any required washers. Allow no more than one (1) single thread within the bolt's final installed and torqued position.

Our Airheads as chock full of OEM grip length specific bolts and machine screws.

[jamestnewsonr65]

I have recently ordered a load of bolts and fasteners from orbital fasteners in the uk. They are really good and have all the variations on tensile strength. The guy who vapour blasted my carbs was an engineer and advised against stainless as it has less tensile strength compared to the zinc plated.

[clonmore1]

Thanks to all,

Excellent advice as always, I feel I have still got so much to learn (enjoying it though).

Thanks

[Lucky_Lou]

I have switched most of the frame fitting bolts with 8.8 stainless Allen screws I don't think that things like the mud guard/Headlamp mountings etc are that critical but I have left the engine mounting bolts alone.
Lou