FORMULATING A PLAN FOR THE WIRING OF YOUR
STREET ROD, HOT ROD OR CUSTOM CAR
By Al Campion
So you have planned how you are
going to
build your car. You have decided on type
of suspension, the engine and drive train components, the
paint and upholstery.
But have you planned the
Electrical System?
It is best to start planning the
electrical
system well before the car is complete. Many people think of the
electrical
system about the time they install the engine and want to hear it run
for the
first time. Usually the installation of the wiring is one of the last
things to
do just prior to installing the seats and upholstery. You also might
want to
run some of the wiring prior to installing the sound proofing
materials. Many
times people find themselves installing the wiring in the car after its
painted
and find that they need to drill a hole in the firewall or kick panel
to route
the wires or they didn't consider the size of the fuse panel. If you
plan ahead
as you assemble the cars mechanical components you can save yourself
some grief
during the wiring job.
Give some thought to where and how
you will
run the wiring. Will you be hiding the headlight and signal light
wiring up
under the front fenders where the splash shields or inner fender wells
attach?
If you are you will need some type of clamps (such as Adel clamps or
welded
tabs) to hang the wiring on. If you are hiding the wire to the
taillights in a
boxed frame, how will you get it into the boxed frame and how will you
repair
it if something happens down the road? What size is the fuse panel and
where
will you mount it? Will you need to fabricate and weld a mounting pad
for the
fuse panel? What holes will you need, where and what grommets will you
use?
Here are some other ideas to make
you think
about the wiring as you assemble the car.
Number one in my book is will it
be 12 volt
or 6 volt? Most cars built or rewired today are going to use a 12-volt
system.
But if you are rewiring an older car and keeping it 6 volts you will
need to
use larger wire than you would in a 12-volt system. DO NOT make the
mistake
that a few have made and use a wiring kit designed for 12 volts on a
6-volt
system. Can you say Fire? Why in the world would anyone want 6 volts?
Well if
you are building a period correct nostalgia car you will probably want
original
6-volt equipment. And if you're wanting to keep that genuine '40 Ford
dash
intact and use the original gauges you have think about converting the
gauges
to operate on 12 volts or figure out how to supply 6 volts to them.
A few thoughts on converting from
6 volts to
12 volts for those of you who are working on an older 6 volt vehicle
and
converting to 12 volts. Most original 6 volt generators can be
converted to 12
volts. 6-volt starters will work just fine on 12 volts. Sometimes
you
will have to change the solenoid to 12 volt but I have found that the 6
volt
unit will work for quit a while. Dash gauges are another story.
You
basically have two choices, 1) send the gauges out and have them
converted to
modern 12-volt operation (very expensive) or 2) use voltage reducers or
resistors to reduce the voltage to 6 volts at the gauge. If you
are
changing from 6-volt positive ground to 12 volt negative ground you
will also
have to wire the gauges opposite of the original wiring for them to
function
properly. There are several ways to reduce the voltage to the gauges.
The old
way was to use a resistor to reduce the voltage but for this to work
properly
you had to know the amount of power the gauge would draw in amperes and
do a
little calculating to figure out the correct resistance. Today we have
the
modern semiconductor and there are Zener Diodes and solid state
transistorized
voltage reducers that work very well. AutoReWire.com and Centech sell
the
diodes for $ 3.00 each. Speedway Motors sells a transistor called
a "Runtz"
that also works but they are a bit more expensive. For reducing the
power to
the 6-volt motors for things like the heater, electric wiper motors,
window and
seat motors the best bet is to use 1 to 1.5 ohm ceramic resistors
specifically
built for the job. AutoReWire.com also sells these.
Sometimes you
will need to use two resistors in a parallel configuration to get the
proper
resistance. If you need help figuring this out please contact me and I
can
help.
Most rodders and custom builders
want the
battery hidden out of sight but accessible. For heaven sake do yourself
a favor
while you're building the rest of the car - Locate the battery and test
fit it
and the cables before painting the car. There is nothing I hate worse
than
having to cut up a floor pan or battery box after the car is finished
because
nobody checked to see if the battery or cables would actually fit.
Battery size (as in Amp Hours) is
another
thing to think about along with the output (Amperage) of the alternator
you
plan on using. The number of electrical options you are installing
determines
both. High output ignitions, stereos with monster amplifiers, halogen
light
bulbs, power seats, power windows, power antenna, power door locks,
power trunk
opener. All of these things need to be considered. If the alternator's
capacity
is not large enough you will end up with a dead battery. The size
of the
cable between the alternator and the battery has to be sized to the
output of
the alternator. If you put a 140 amp alternator in a car with a
10 gauge
wire between the two you will burn up the wire if the battery goes dead
and the
alternator goes to full charge.
On most GM vehicles the charge
wire, ignition feed wire, fuse panel feed wires and the alternator
sense (# 2) wire are spliced together in the wire harness and a fusible
link at the starter solenoid protects the entire system. On most
aftermarket kits and home built harnesses the charge wire is run from
the alternator to the starter solenoid without any protection. I like to install a 16 gauge
fusible link at
the alternator to protect the charge wire to the battery
solenoid. Also DO NOT
wire
the car
without some sort of fuse or fusible link between the starter solenoid
and the
wire to the fuse panel and ignition switch. All it takes is a
short to burn
the car
to the ground. I personally prefer a fusible link as they work
like a slow blow fuse but others have
their
own preferences.
Battery cable size is another thing to think about along with where it will be located and mounted to the body or frame. I tend to go with heavier than needed cable on everything I do. On short runs I might use something like a number 2 gauge battery cable but if I'm running cable all the way from the trunk on a race car I will probably use a number 1/0 welding cable. I use welding cable because it has more individual wires for the size of the cable (less resistance) and is more flexible than battery cable. Just remember the farther you run a cable (wire) the larger it needs to be.
Battery cable connections MUST be clean and
tight. I always install internal and external star lock washers on all
connections made to a chassis ground after properly cleaning it to bare
metal. Then coat with dielectric grease or paint. Most
of the electrical problems that I find on street rods, hot rods and
customs are related to poor grounding. Always ground the battery to the
engine block and then ground the engine to the chassis and to the body.
If you are set on using the frame for a ground cable, (battery mounted
in the rear of the vehicle) make very sure that you properly connect
the cable from the battery to the frame and another cable from the
frame to the engine. Down the road when the car doesn't want to start
check the cables where they bolt to the frame and the engine. They will
be loose, dirty and/or corroded. One good way to use the frame for a
ground is to weld a 3/8" stainless steel bolt to the frame. Tape the
threads off when painting or coating the frame. When you're ready to
connect the cable. Apply some dielectric grease to the threads, run a
nut down to the weld, then install a heavy flat washer followed by an
internal/external star washer, followed by the battery cable, followed
by another star washer, flat washer and nylock nut all liberally coated
with dielectric grease.
Wiring Harness and Fuse Panel
Ok now the good stuff. What should you choose for
a wiring harness. If you're thinking of going out to the local wrecking
yard and using something off a donor vehicle you're sick. This is
admittedly the cheapest way you can wire a car. But your time has to be
worth something. By the time you drive to the yard, find something that
might work, spend an hour or more getting every thing you think you
might need and drive home, you will have spent half a day and how many
?? bucks and all you have to show for it is a pile of spaghetti. Plus
it will take you another 4 hours to sort it all out before you can even
start to install it. You can also buy new wire by the roll and
build your own harness but you will have a lot more money invested than
a kit if you purchase multiple colors and do it right.
There are way too many, nice aftermarket wiring
harnesses available that make the job a simple one. I like to use a
fuse for
every major circuit in the vehicle. I admit this is a little over the
top, but when a light bulb shorts out and blows a fuse the entire car
doesn't blackout. So again do the planning and decide what you
need.
The next option is the less expensive panels and harnesses most of which are already pre-terminated at the panel. Most of these use an ATO/ATC or mini blade fuse panel with the turn and hazard flasher on the panel. Painless Wiring, Ron Francis, EZ Wiring, Centech, Haywire, and Enos Custom Components all come to mind and have good instructions on how to install their specific kits or panels.
A few thoughts on some of the wiring kits available on the market. The available kits mainly fall into two categories: Modular and Pre-terminated. The modular kits take a little bit longer to install because you have to terminate both ends of each wire. The nice thing about these kits is they allow you to run the wiring anywhere you see fit. I like these systems for this very reason. Ron Francis Wiring has been building these kits longer than anybody in the business. Centech Wiring also has a very nice 13 fuse 23 circuit kit with a high quality printed circuit board with a good looking stainless steel cover that only measures 3.5 X 6 inches. These kits are about as complete as they come.
On the less expensive end are the GM style fuse
panel kits with the wires pre-terminated in the panel like Painless
Wiring and Centech's GV-16.. These panels can
be installed a little quicker because of this design. We stock the
Centech GV-16 with and without switches. The balance of
the wiring, which is not connected to the fuse panel, has the necessary
terminals machine crimped and dip soldered in place with heat shrink
tube installed.
In the last few years there has been an influx of
import kits made in China and everything from soup to nuts available on
Ebay. These kits are inexpensive but beware of
quality control and complete kits. If you are buying a kit off
Ebay make sure the seller will refund all of your money including the
shipping if you are not satisfied with the product. The majority
of the kits I see on Ebay are not complete in any way. Remember
the old saying " You get what you pay for".
So which way do you go? I can't tell you. You will have to decide for yourself. I hope this information helps. I can say this much, plan out your wiring as well as you plan out the design of the rest of the car. Be safe and install quality products. Most of all have fun and drive careful.
Thanks for visiting and putting up with my
opinion.
Al
Need any help with
your wiring problems just call or e-mail me. Any and all comments are
welcome.
If you feel something should be added please let me know.
Al@AutoReWire.com
al