Re: [alfa] What I learned about SS exhaust fasteners

[Alan Lambert <lechefgerard@xxxxxxxxx>]

I have a Stebro system that's now been on three 164's. Only problem
ever with stainless fasteners is that some came loose, not jammed.


--- Jay Mackro <jmackro@domain.elided> wrote:
> In a recent digest, I mentioned that stainless steel bolts + nuts
> tended
> to freeze up, especially when used on exhaust systems.  I received a
> number of replies, and learned a great deal about this problem. 
> Thanks
> to all who responded.
> 
> The concensus seems to be that you MUST use an anti-seize whenever
> using SS hardware, even when it isn't exposed to heat.  One of the
> replies
> that addressed the problem most directly advised:
> 
>     use zinc plated steel bolts, stainless steel split washers and
> brass nuts
> 
> which seems like the best approach.  While brass nuts won't take a
> lot
> of torque (e.g., they're easy to strip if you over tighten on
> assembly),
> these
> joints don't require a lot of clamping force, and the anti-corrosion
> properties
> of brass probably outweigh its lack of strength.
> 
> The problem of exhaust system fasteners is an intersting one - you
> need
> two properties:
> 
>   1) The joint shouldn't come loose under vibration in the early days
> - e.g.,
> before everything rusts up solid.  I have had problems in this area
> when the
> lock washer anneals from the heat, and the still unrusted nut & bolt
> just
> vibrate loose.
> 
>   2) The joint shouldn't lock up due to corrosion, making it
> impossible to
> take apart after it has been in place for a few years.  This is less
> of a
> problem
> where the joint is easily accessable - like on the catalytic
> converter -
> since
> it is easy to put a wrench on both the nut and bolt head, and if the
> fastener
> fractures, so what?  But, corrosion can be a real issue when the
> fastener is
> difficult to access - like where an early Alfa's cast iron manifold
> bolts to
> the
> downpipes.  There, it is difficult to apply enough torque to some of
> the
> fasteners to just fracture them when they corrode.
> 
> I guess the tried and true method of using steel bolts and brass nuts
> is
> probably the best solution.
> 
> Jay Mackro, San Juan Capistrano Ca.
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=====
Best Regards,

Alan Lambert
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