by
John McMillan
Most
of the following are faults and/or safety hazards that I’ve encountered
in Model A’s and other less worthy vehicles. The cures are neither
expensive nor technically difficult.
BATTERY
Hold Down: Without a hold down, the battery can bounce
around, resulting in case cracks and acid leakage or cable shifting and
abrasion resulting in a possible short. Easy to correct.
Ground Strap: Attachment to frame should be to BARE
METAL. We usually apply lots of paint to the frame and unless some is
removed where the ground strap attaches, then a solid ground cannot be
achieved. A coat of dielectric grease helps to promote good contact and
slows rusting when applied to bare metal. With a poor ground, the starter
will turn real slow, and draw far more current than it should. Easy to
fix.
Cable Size: Modern cables that you can buy at your
local auto shop are too small. Small cables cannot carry the current draw
of a starter motor safely. They will overheat and the starter will turn
slowly. The cable size should be No. 1. These can be special ordered at
the local parts house, or buy them from a vintage Ford dealer.
Caps: Make sure the battery vent caps are not plugged.
If they’re plugged, and the charge rate is high, the battery can
explode from gas buildup inside the battery. Very exciting, very messy
and very dangerous. Plugged caps are caused by dirt and, I suspect, by
using hard water in the battery. Clean caps and distilled water are the
inexpensive answer. I had one blow up in a German Model A (VW) and the
clean up alone took about 8 hours.
Cable routing: The negative cable to the starter
MUST be routed according to Ford’s plan. See illustrations in any
of the Ford repair manuals. Other routings most likely will cause cable
insulation chafing and a resulting short circuit. Even if you installed
a fuse, this is not a fused cable, and a fire is very likely. I’ve
seen this several times, the last time at Big Bear when a member complained
of white smoke every time he stepped on the brake. The pedal pushed the
battery cable against the bellhousing and shorted out. If a fire starts
here, you need to disconnect the battery to stop the fire source. Very
hard to get to, you might wind up watching your car burn while you try
to remember if your fire insurance is paid up. This kind of fire can also
happen after you’ve parked the car in your garage. Real easy to fix.
Note that no safety switch or fuse installation will eliminate this hazard,
the only way to cure the problem is to "do it right the first time",
and it takes no more effort than to do it wrong.
STARTER
Grounding: Must have a good ground for proper operation.
A slow grinding starter is a hot starter and hot cables are not healthy
cables. If your starter spins real slow, you may need to add a second
ground strap from the starter mounting bolt or a transmission bolt to
a bare spot on the frame. If you have Float a Motor mounts, I think this
secondary cable is almost required.
Starter Switch: This is one of the items that must
have been designed by an incompetent engineer. Check yours for bad insulation
and shorting against the body of the switch, both very common faults with
this switch. Another fault is that the switch can "weld" itself
to the starter contact and keep on cranking even after you’ve removed
your foot from the starter rod. If this happens, reach down and try to
pull up on the starter rod. Sometimes this doesn’t stop the cranking,
and the starter will continue running until the battery dies or the starter
burns out. The only way to stop this if you’ve installed a mater
cut off switch, more about this later.
BRAKE LIGHT SWITCH
28-29 Switch: The original switches are usually only
a problem in that they can be a pain to adjust so that they work. The
reproduction switches are for the most part a real problem. Actually,
most that I’ve seen are a fire waiting to happen. The problem is
in the insulation around the studs. A lot of the repops have poor quality
red fiber that cracks easily. If this happens on the hot terminal, a short
will occur that can set the input wire on fire. Symptom is a discharge
reading on the ammeter and poor running engine because all the power is
going into melting the wire. If the secondary terminal shorts out you’ll
see a high discharge reading whenever you step on the brake. To check
the switch, remove it, hook an ohmmeter from stud to ground and force
the stud in all directions. If it shorts out on either stud, replace the
switch. Check new switches as well. I’ve seen them in failure right
out of the box. Sample melted wire available for inspection. This is another
fault that can start a fire when your car is parked. A fuse MAY protect
you, but 25 amps is still enough to start a fire. I fixed mine by taking
it apart and machining new insulators out of delrin plastic.
30-31 Switch: Although not a safety issue, operation
can be improved and squeak eliminated by silver brazing and reaming the
operating rod hole in the switch body.
CUTOUT
Points Stuck Open: This is the more common failure.
Points won’t close, battery won’t charge, battery dies, and
your generator fries because it’s trying to charge the whole universe.
Not a safety issue, but very unpleasant when it happens away from home.
Short term fix is to install a jumper wire across the cutout terminals
so that the generator works properly. Just remember to disconnect the
wire when you shut off the engine. If you’ve installed
a master cut off switch you can just shut the switch off.
Points Stuck Closed: This is another problem, less
common, but a real hazard. When they stick closed, the generator functions
normally when the engine is running, When the engine is shut off, the
battery feeds the generator, which now thinks it is a starter motor and
tries to turn the engine over, resulting in a burned out generator, a
melted out charging wire, a dead battery or a burned out car. This is
another garage fire potential. If you see a heavy discharge on the ammeter
when the engine is off, look for this problem. Disconnect the wire form
the "batt" side of the cutout. A fuse helps here because it
will usually blow. Best solution is to install a diode kit in the cutout.
AMMETER
Cap Nuts: Using plain nuts on the back of an ammeter
is an invitation to a short circuit against the fuel tank. Use the plastic
cap nuts that Ford designed for that use.
Meter Shorts: Check that there is no possibility
of a short on the studs to the ammeter case back, especially on original
meters. I had a near mint meter short out due to 70 year old insulation
failure. This stuff does not last forever. The short melted the insulation
from the wire that runs from the meter to the junction box. This is one
part where a repop may well be better than the original.
HEADLAMP
Sockets: Check that the spring- loaded contacts inside
the bulb sockets do not contact the wall of the socket. Some reproduction
sockets can be pretty sloppy in this area. Contact will result in a short
circuit whenever the lights are turned on, either in one or both high
and low beam settings.
Connectors: These are the little troublesome connectors
at the base of the headlamp buckets. Probably the best solution is to
hardwire the lamps thereby bypassing those little rubber gizzies.
MISCELLANY
Grommets: If a wire is going to pass through sheet
metal, always use a rubber grommet. If not, vibration will wear through
the insulation and a short will result.
Frayed Wires: If the insulation is frayed, replace
or tape the frayed area.
Wire Routing: If you are routing wires, use common
sense. The worst example I have seen was a fuel pump wire strapped to
a fuel line. The fuel line was leaky (Model A, big surprise}, the fuel
dissolved the wire insulation so that the wire became bare. Use your imagination
as to what could happen if a spark occurred.
Electric Fuel Pump: If you add one, don’t forget
to add a regulator so that the pump pressure isn’t so high that fuel
comes out of the carburetor. Old carburetor fuel valves cannot handle
the pressure of an unregulated pump. Although not an electrical item,
I did see what happened when fuel from an unregulated pump met a stray
spark from a magneto on a 1913 Mercer.
Good Rule: Always check the ammeter when you shut
off your engine. Never walk away from a Model A that registers a heavy
discharge. If you can’t fix the problem, then disconnect the battery
ground cable.
Hint: A light coating of dielectric grease on all
electrical connections including light bulb bases will promote good electrical
contact and inhibit corrosion. It is available at most electronic supply
houses under various brand names and from your local auto parts house
as Permatex #67V Dielectric Tune-Up Grease. If this grease is used on
light bulbs, fuses, connectors etc., then removal is easy, without the
usual sticking and subsequent breakage.
GOOD ADDITIONS
Fuse Holder: These are available from all Model A
suppliers for a few dollars and are very easy to install. They provide
a lot of protection from the bad results of electrical faults. Pulling
the fuse when you park your car shuts off most everything and helps prevent
theft as well.
Master Cut-Off Switch: Probably the best safety investment
for an antique car. About $25 to buy. Cuts off all power past the battery.
An additional benefit is that the battery will maintain a charge longer
if you make a habit of always turning the power off whenever you stop
the car. Everything connected to a battery will draw small amounts of
current even when "off" due to resistance at the connections.
If the switch is off, the battery does not discharge. I would not have
an old car in my garage that did not have a power cut off switch, unless
the battery was disconnected.
Fire Extinguisher: When all else fails and fate is working overtime,
an extinguisher is really nice to have. Lacking one, try to smother the
flames with sand or a blanket, jacket or whatever. If you can’t put
out the fire, enjoy the spectacle, plan the restoration of your next vehicle,
and figure out where you can put the hard luck trophy.Source: http://www.ocmafc.com/techarticles/electricalsafety.htm
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