Re: Alternator leads on MT-14's and MT-19's

["Bill Owen" <wowen@hotmail.com>]

John,
The engine compartment on these aircooled engines presents a really 
harsh environment for electrical connections - very hot, high vibration, 
and corrosive gasses from combustion by-products.  There are several 
requirements that must be met to make a reliable connection under these 
conditions.  The wire must be flexible, heat resistant and corrosion 
resistant.  The connection from the wire to the connector must be 
mechanically sound, heat resistant and corrosion resistant.  As you and 
others have already mentioned, the wire should be multi-stranded for 
vibration resistance, have high temp insulation, and the strands should 
be tinned or coated to resist corrosion.  The wire should be fastened to 
the alternator or a bracket near the connection to provide strain relief 
for the connection.  The connector should be mechanically strong - 
crimped or tightly wrapped around a post or hole.  Finally, the 
connection needs to be "gas tight" to prevent corrosion.  
I think the best way to make a gas tight connection is to solder it.  
The solder prevents hot, corrosive gasses from getting to the interface 
between the wire and the connector which leads to corrosion and 
eventually to joint failure.  The keys to a successful solder joint are:  
1- make sure both surfaces are clean, 2 - wire and connector are 
mechanically solid, 3 - do not move the connection when the solder is 
cooling (a cold solder joint is not gas tight) 4- strain relieved so the 
wire that is more brittle due to the solder does not flex and break due 
to vibration.
I have soldered every joint I have worked on in my car - I have quite a 
few yet to go - and these have not failed (so far - knock on wood).  The 
crimp connections (inherited) in this car have not fared as well.  I 
usually carry crimp connections with me for quick repairs, but I solder 
them when I get home to make sure they hold up long term.
Soldering is not as fast and easy as a crimp connector, but I think  in 
this severe environment soldering is well worth the extra effort!
Happy Wiring!
Bill

>Date: Mon, 28 Sep 1998 22:18:19 -0700
>To: speeders@lists.cirr.com
>From: "JohnM. Smith" <jmsmith@sonic.net>
>Subject: Alternator leads on MT-14's and MT-19's
>
>On MOW's Pacific Northwest Tour last week-- approx. 550+ miles on three
>railroads-- we had a couple of instances of broken leads to the 
alternator.

>I went over the electrics when I got home and sure enough, one lead to 
the
>alternator had broken off just above the crimp.  The stranded copper 
wire
>also seemed fairly brittle.  I patched in a piece of new wire, but this
>started me thinking:
>
>The wiring on these cars is subjected to tremendous vibration, 
particularly
>when running at 25+ mph, even on pretty good track.  The alternator 
leads in
>particular seem vulnerable and are brittle and not very flexible 
(although I
>also found a couple of other not-very-tight connections).  I'm going to
>watch the alternator leads more carefully in the future, but if any of 
the
>readers know of a commercially-available super-flexible insulated 
stranded
>14 guage wire (probably many strands of very fine guage wire), I'd
>appreciate reference to sources, and would like to eventually splice in 
a
>super-flexible section on these stiff copper leads for better insurance
>against electrical failures in the future.  Thanks-- John M. Smith    
>
>


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