Getting into harness
One of the most critical jobs in restoring your sweet old Cad or LaSalle is going to be the wiring, yet one of the most fun and intriguing parts of the restoration.
I have seen self-restorers who barely knew the difference between a wrench and a pair of pliers dig into a major engine rebuild, and some rather experienced mechanics that were afraid to even touch anything electrical, beyond maybe changing a light bulb.
In fact, some will avoid replacing the wiring, and choose to patch up the old wiring with tape. In reality, the wiring should be the first thing you replace if you are doing your restoration one piece at a time. The danger of trying to get by with patching old wiring is you are risking some rather weird happenings, if not a serious fire, causing you to lose the whole car. After all, a moderate expense for a new wiring loom is probably the best investment you can make towards trouble-free driving.
There are several suppliers to the hobby for wiring looms, and over the years I have either tried most of them or seen them tried, or even had to go in and help someone figure out what went wrong. Of the five major suppliers, two of them I could never recommend.
As for the other three, one is priced out of reason, one uses easily-lost paper tags, and my old standby, unfortunately, doesn’t advertise with us so I can’t mention the name. But I have the best luck with them.
They use very good quality wire that is modern on the inside but looks original on the outside. Not only that, their price is reasonable and you get the complete loom for one price. The loom comes well marked, along with accurate ledgers and wiring diagram.
Assuming you now have the new loom in the mail, unpack, look it over and identify all the leads by their number and where they are going to go. At this point in time, make sure your wife isn’t going to have spaghetti for supper. I guarantee that when you first look at it spread over your garage floor, it will make you think of multi-colored spaghetti. It’s real easy if you take it one step, or rather one wire at a time. If this is your first attempt at wiring, I would advise starting with each individual outside fixture, i.e. each taillight, each parking light and each headlight one at a time.
These wiring looms are usually separate from the main loom. This will also give you experience in putting new wire into old fixtures. A “trade secret” I learned was to use small 1/8-inch steel pop rivets for the ends of the wires into light sockets. After stripping about 3/16 of an inch from the end of the wire, you assemble the socket onto the wire, use your grinder to grind down the head of the pop rivet, take the rod out of the rivet, put the rivet over the wire and solder the end. After you get these all done with good connections, you are ready to tackle the main harness.
The next thing you want to do is to take out the old harness. A tip that will help you here is to take out the front seat and carefully take the old wires off of the instruments and the light switch. You will actually be better off to take the light switch from the dash and plan to wire it on the bench. You will also find that you want to cut the old harness near the firewall and take out the dash portion separate from the engine compartment.
Now place the new loom on the floor and put your old loom alongside. Again, take time to go over the diagrams and number ledgers to recognize where all of the wires go. At this point, you will find that you will have to use your old light sockets from the dash, Clean them up good, take them apart and rebuild them with pop rivets like you did the other light sockets. The headlight switch is somewhat of a nerve center for your wiring loom with many terminals, and by now you know exactly why I suggested doing this on the bench.
When you have all the sockets, switches, terminals, etc. put together, it is time to put all of the engine compartment wires through the firewall from the inside. Hook up all of the dash wires after putting in new bulbs, install the dash light and the light switch. Now is the time to make sure you have a neat routing and snug up the whole loom. The easy part is hooking up the engine compartments, the headlights, dimmer switch, stop light switch, the horns, taillights, turn signals, etc. The big secret is to do them one wire at a time.
See now, that wasn’t really that hard, was it? Just be sure you make good clean and solid connections and that you have good grounds to the frame, the body, the dash and the engine itself. By the way, if you forgot to disconnect the battery before you started all of this, it is time to get out your fire insurance policy.
Get into your harness and I’ll see ya next month.