replaced 02 sensor - in defense of soldering

[Tony Lum]

At 01:19 PM 7/18/2003 -0400, SJ wrote:

>For the soldering challenged, crimping will produce far fewer errors. But, a
>ratchetting crimper is a must. In addition, skill and tools for stripping
>the wires are important. I've seen crimped connections with over half the
>wires nicked and broken. Nicked strands in a soldered connection are usually
>soldered over by wicking action.
>
>For the soldering proficient, the very few of us, solder is fine as an
>electrical connection. Just use common sense regarding when and how to use
>it.
>
>
>SJ
>85 Dodge PU, D-250, 318, auto
>85 Audi 4k - - sold but still on the road
>88 Audi 5kq
>90 Audi 100q

As SJ correctly describes, a ratcheting crimper is the only tool to use
if  you're going to crimp connectors.  The standard crimper you see for $5
in hardware stores will NOT do the job correctly.  A ratcheting crimper and
the correct die will cost anywhere from $45-70.

My company does mil-spec work for aerospace applications and soldering is
not permitted.  Soldering produces a brittle joint right at the end of the
connector and wire joint that can fracture under vibration and heaven help
you if you use acid core flux solder.  Every type of contact has its own
specific die and the tools are calibrated and tested at specified
intervals.  A pull test is performed where the wire is crimped and then
pulled to test the quality of the crimp.

There are 2 other reasons I prefer crimping: 1. crimping is faster and
doesn't require and holding or  twisting of the wires while you try to
apply the heat. 2. heat from the soldering iron or gun can inadvertently
damage other wires.  You also have to insulate the connection with heat
shrink to tape, another step.  Try fixing a broken wire harness in the
trunk of your 4kq by soldering.  Its nearly impossible to manuver a
soldering iron in that tight environment.  I tried and it was taking way
too long.  I had enough broken wires in that harness (which flexes
constantly and is pretty short) that I ended up just cutting all the wires
and crimping in a 6 inch "jumper" extension harness.  Been working flawless
for 3 years now.

Another situation where a crimp is superior is splicing in an additional
wire in the middle of a harness.  Because the harness is tightly wrapped,
there isn't enough wire to pull out to solder.  Instead you cut the wire
and place an inline crimp splice (available at any Radio Shack).  The
splice adds length which doesn't put tension on the wire.  Had to do this
on my Mom's 100 Avant which strangely did not come with a trip computer.  I
changed instrument clusters and the right hand stalk and needed to splice
in 3 wires to feed the mass airflow plate position pot back to the trip
computer.  I soldered the first connection and it took a while trying to
get all the ends to meet up to solder.  I crimped the butt splice in on the
2 other wires and finished pretty quickly.  I'm still a little worried
about that first connection and may redo it eventually.

Lastly, when doing O2 sensors, you use adhesive lined heat shrink crimp
splices available at marine stores.  After crimping the wire, you hit the
insulation with a heat gun which melts the adhesive and seals the
joint.  Some of the adhesive ooze out the end to seal the ends.

BTW,  I am certified by my company to perform milspec soldering.

Regards



-Tony

'80 5KS
83 urquattro #DA900302
'85 4kq
'87 5kcstq
'87.5 coupe GT