Date:         Wed, 20 Nov 96 18:20:31 EST
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         Sean Bartnik <sbart7kb@www.mwc.edu>
Subject:      Solenoid Sermon

Hey all,
	Sorry to continue this thread, but I found Bob's sermon on solenoids so
I thought I'd post it.  I'll shut up after this :)


"Solenoid? We don' need no steeking solenoid!"
or...
St. Muir and the By-Pass Solenoid

This one really gets me hot under the collar, first because it ain't a
by-pass-anything, and second because the usual method, using an old Ford
starter solenoid a la St. Muir is dumber than hell, partly because it ain't
a
solenoid at all but a contactor, and finally because you just don't need a
starter contactor for this particular job.

The problem is that Volkswagen feeds their starter solenoid 12vdc by way of
China. They run the juice all the way up to the front of the vehicle,
through the starter switch which isn't all that reliable to begin with, then
all the way back to the solenoid -- which is where the juice started its
journey to begin with.

By the time those 12 volts have marched up front, squeezed through the
switch
terminals and hiked all the way back to the solenoid about of half of them
are dead and the others have blisters. They jump inside the solenoid, put
their electronic shoulders to the wheel but find they're played out by the
trip. If the solenoid moves at all it does so sluggishly, often not enough
to close the contactor terminals that provide juice to the starter motor.

The fix is to keep those 12 volts from wasting their time and energy on that
useless hike by putting in a RELAY. That's what that Ford contactor is
pretending to be. The joke is, the contactor takes almost as much juice as
the VW solenoid! A wiser choice is a headlight or horn relay. Cheap, easy
to find and easy to mount. Screw it to the fender well inside the engine
compartment to help keep the terminals clean.

What the relay does is tell those 12 volts when to go to work on the
solenoid. You wire your relay with the same wire originally used for the VW
starter solenoid but you install new, heavier wires -- with a shorter run to
the battery and solenoid -- from your relay. Since a headlight relay only
needs an itty-bitty amount of power to pick or transfer, the original wiring
provides more than enough energy despite its long run. And since your new,
heavier wiring provides a shorter, neater, cleaner, prettier, healthier and
politically more correct run between the battery and the VW starter
solenoid,
it fires right up every time.

I understand Gene Berg started selling Ford contactors because he got tired
of trying to explain to St. Muir deciples that St. John didn't know very
much
about elektrissity. I know a whole bunch about elektrissity and I'm still
alive, even though I use a headlight relay to pick my solenoid and a horn
relay to turn on my back-up light and an itty-bitty microampere relay out of
a short-wave radio to tell my external cooling fan when to turn on, although
a Ford contactor would have done the job -- sorta -- in each and every case
and would have, if St. Muir had thought of back-up lights and cooling fans.
("Back-up lights! We don' need no steeeking back-up lights!")

Sermonette

Cold weather brings home the problem of the voltage drop in the long wiring
runs common to a Volkswagen bus. If you want reliable starts and brighter
headlights you need to know more about heavier gauge main buss wiring and
the
use of relays. You are the mechanic-in-charge of your vehicle. Sometimes
that calls for you to be an electrician as well.

Bob