Exhaust System Fasteners

["Steve D'Gerolamo" <steved3@xxxxxxx>]

Alfred Sutlick writes (on the E24 digest):
Mike,
I neglected to mention that all of the nuts on the exhaust system are of the
self-locking type.  Do not attempt to use standard nuts.  Any qualified
parts supplier should automatically give you the correct ones for this
application, but just in case....
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			The exhaust system nuts and bolts from BMW are carbon steel, the nuts
generally with copper plating.  This is for heat resistance.  Removing
these copper plated (if the were all copper, they would not be magnetic)
nuts after years on the car can be quite a chore.  Air chisels, cutoff
wheels and reciprocating saws are generally the shortcut to getting this
hardware off (I use a 12,000 stroke per minute air saw made by SIG of
Switzerland which allows me to get into very tight spots).

		For the cat to muffler flange connections, I supply stainless steel
hardware which should makes things easier the next time the system has to
come down to replace the muffler or do any drivetrain work.  Note that all
pieces must be stainless....for most E24 cars this is 3 Din931-A2-8x35 and
3 Din931-A2-8x45 bolts (Din 931 is part thread and A2 is 304
stainless...A4/316 is not required).  In conjunction with these bolts, I
use 6 serrated lockwashers (these provide much more effective locking than
spring or split washers) and 6 Din6923-A20M8 flanged nuts.  It took me 2
months to get these special flanged nuts and lockwashers (in stainless) in
from Germany.  This hardware will come apart 5 years from now as easy as it
goes on today.

		Unfortunately, for the manifold connections with steel studs (both in the
manifold and in the head), you must use the copper plated steel locknuts.
Installing stainless nuts on non-stainless studs is not advisable.  SD
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Steve D'Gerolamo - The Ultimate Garage
201-262-0412 / steved3@domain.elided / http://www.ultimategarage.com

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