Subject: LRO: Re: corrosion issues/shipfitters disease/sil

From: "C. Marin Faure" <[email-masked]>
Date: Tue, 15 May 2001 01:50:59 -0700

Date: Mon, 30 Apr 2001 01:45:24 -1000
From: "Hope Peter" <[email-masked]>
Subject: LRO: Re: corrosion issues/shipfitters disease/sil

>  I'd also like to hear from folks on using plastic discs under
> washers in contact with aluminum, as well as plastic between the tub and
> the frame mounting tabs?

If you're concerned about the potential for corrosion where dissimilar
metals come in contact, you can put all the plastic washers you want
between the parts or panels, but it won't do you a lick of good if the
fastener itself contacts the metal, which it pretty much has to do if it's
going to hold them together.   Unless you use some sort of insulating
sleeve to keep the barrel and threads of the fastener from making a
conductive connection between the two pieces of metal you're joining, the
potential for electrolysis will always be there through the fastener,
especially if it screws into one or both pieces of metal, as a sheet metal
screw tends to do.

I've seen examples where people have pointed with great pride at the
wonderful insulating job they though they did using plastic, nylon, etc.
washers with fasteners that connected aluminum and steel components on a
floatplane, only to be dismayed by the repair bills when corrosion formed
around the fasteners anyway.  They had overlooked the fact that the
fastener itself formed the contact between the two metals.  Their fancy
insulating washer system looked great but accomplished nothing.  If you
want to eliminate the potential for electrolysis and its resulting
corrosion, there cannot be ANY conductive connection between the two pieces
of dissimilar metals, and that includes the fasteners themselves.  There
are several ways of accomplishing this, but they involve more than just
sticking a plastic washer underneath the metal washer at each end of a
fastener.

________________________
C. Marin Faure
  (original owner)
  1973 Land Rover Series III-88
  1991 Range Rover Vogue SE
   Seattle, WA