Stainless Steel Nuts & bolts

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Mar 7, 2005
Where possible I have tried to use Stainless Steel nuts & bolts when reassembling bits on my MkIIa. eg. Mudguards, exhaust, sidecovers, z-plates etc.

I go along to my SS shop and get shuffled to a corner where the UNF bits live. This is an expensive corner as I have found out. The 1/4 and 5/8 bolts (and nuts) appear to be 4 times more expensive than the Whitworth (or metric) SS equivalents.

Is there a reason for using the UNF parts? They have a much finer thread than then other bolts which may resist the major vibration a Norton twin generates.

Should I just grin & put up with it or look at the alternatives?

Personally, I would stick with the same thread profile as the original fasteners. A finer thread will not loose its pre-load as easily as a coarse thread.

Be careful when making up stainless on stainless, as the threads have a tendency to gall. Grease with a high Moly content will help prevent thread galling. Also, stainless steel fasteners are generally not as strong as their carbon steel cousins, so I would not use stainless for highly stressed bolting applications.


What about putting stainless nuts on carbon steel studs. Some of the "fixing kits" don't replace the studs for the head to cylinder.


First let me apologize for my grammatical error in the previous post: I sometimes get “loose” and “lose” mixed up. I know better, it just pops out uncontrollably, like a sneeze.

Funny you should mention stainless steel fasteners for Norton cylinder head applications. I asked this forum a very similar question over a year ago. I was concerned that stainless steel head bolts would stretch, allowing the head to separate slightly from the cylinder, resulting in a blown gasket.

However, several forum members reported that they had been using stainless steel head bolts for years with good results. Notwithstanding this favorable response, I’m still a bit suspicious about using stainless steel fasteners to bolt down the cylinder head.


S/S fasteners

The 30lb/ft torque on the 3/8" bolts and 20lb/ft on the 5/16" isn't all that much stress for s/s head bolts/nuts. I'm one that has been using s/s fasteners on my Commando for years. The only head gasket problems have occurred when using a copper gasket. My combat engine doesn't like these preferring the composition flame-ring type. There are no instances of s/s on s/s anywhere as the original studs are being used with s/s nuts or the s/s bolts thread into the iron cylinder.
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