Stainless steel fasteners

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Stainless steel fasteners

Postby 850norton » Sat Jan 16, 2010 12:56 am

Hopefully someone who knows more about these things than I can answer this: is there a downside to using stainless steel fasteners on timing/primary covers?

I seem to remember hearing something about mixing stainless with alloy not being a good idea for some reason, but I can't remember why. I've seen them on eBay for my BSA B25/B44 motors and wondereed if they'd be any good.
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'68 BSA B25 Sarfire, '70 BSA B44 Victor Special
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Re: Stainless steel fasteners

Postby Stuart SS » Sat Jan 16, 2010 1:04 am

Mate ~ I fitted SS allen keys to the Commando, including the timing case~ in 1993 when it was restored ~ and I have NEVER had an issue with them ~
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Re: Stainless steel fasteners

Postby Bill » Sat Jan 16, 2010 1:16 am

Stainless can react with the ally causing the ally to contract around the stainless screw. Make sure the internal threads are clean (run a plug tap down them) and use copper slip. u k fl ag
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Re: Stainless steel fasteners

Postby 850norton » Sat Jan 16, 2010 1:22 am

No problems since 1993 is a good endorsement Stuart.

I it there was something to do with a reaction between the two metals but couldn't be sure. Will have to make sure that everything is spotless if I do use them.

Ta guys. :208
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Re: Stainless steel fasteners

Postby NotTriumphtwin » Sat Jan 16, 2010 1:38 am

I have stainless allens on all three covers, and the points cover too and haven't had any problems. I like them and yes for sure keep threads clean but I have never used any anti slip, good advice.
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Re: Stainless steel fasteners

Postby Welsh Wizard » Sat Jan 16, 2010 7:30 am

most steels react with alli,

Galvanic Reaction Between Stainless Steel and Aluminum
http://en.wikipedia.org/wiki/Image:Redu ... tials2.PNG

The aluminium/steel system would form a little battery, and galvanic corrosion would occur; the aluminium wouldn't last long. Anodising would help, thereby delaying the inevitable.
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Re: Stainless steel fasteners

Postby Stuart SS » Sat Jan 16, 2010 10:05 am

Intriguing as to the circumstances that would create this scenario ~

My Commando for example was built in a coastal environment ` spent time in an almost zero humidity environment then returned a temporate zone and coastal before moving to a tropical region .. all over 15 years plus. I have had a number f the SS screws out and back. but NO problems ~

Dare I suggest over kill on science ~ ~

Text books are writtne in all very good theory and practice.. but how does science explain real time life ... seen it all before ~ rock :210
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Re: Stainless steel fasteners

Postby graffian » Sat Jan 16, 2010 10:35 pm

This is a very real problem. I have seen the result quite a few times.
I am told Duralac is the recomended goo to put on disimilar fasteners/parts.
Have to say I have been using them in all the usual applications and haven't had any problems.
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